[xiph-commits] r11714 - trunk/theora/doc
giles at svn.xiph.org
giles at svn.xiph.org
Fri Jul 21 10:09:31 PDT 2006
Author: giles
Date: 2006-07-21 10:09:30 -0700 (Fri, 21 Jul 2006)
New Revision: 11714
Added:
trunk/theora/doc/draft-ietf-avt-rtp-theora-00.txt
Removed:
trunk/theora/doc/draft-barbato-avt-rtp-theora-01.txt
Modified:
trunk/theora/doc/Makefile.am
Log:
Sync the text version of the RTP payload draft with the new xml.
Modified: trunk/theora/doc/Makefile.am
===================================================================
--- trunk/theora/doc/Makefile.am 2006-07-21 16:53:25 UTC (rev 11713)
+++ trunk/theora/doc/Makefile.am 2006-07-21 17:09:30 UTC (rev 11714)
@@ -7,8 +7,8 @@
built_docs =
static_docs = vp3-format.txt color.html \
- draft-barbato-avt-rtp-theora-01.xml \
- draft-barbato-avt-rtp-theora-01.txt
+ draft-ietf-avt-rtp-theora-00.xml \
+ draft-ietf-avt-rtp-theora-00.txt
doc_DATA = $(built_docs) $(static_docs) doxygen-build.stamp
Deleted: trunk/theora/doc/draft-barbato-avt-rtp-theora-01.txt
===================================================================
--- trunk/theora/doc/draft-barbato-avt-rtp-theora-01.txt 2006-07-21 16:53:25 UTC (rev 11713)
+++ trunk/theora/doc/draft-barbato-avt-rtp-theora-01.txt 2006-07-21 17:09:30 UTC (rev 11714)
@@ -1,1402 +0,0 @@
-
-
-
-
-AVT Working Group L. Barbato
-Internet-Draft Xiph.Org
-Expires: December 18, 2006 June 16, 2006
-
-
- draft-barbato-avt-rtp-theora-01
- RTP Payload Format for Theora Encoded Video
-
-Status of this Memo
-
- By submitting this Internet-Draft, each author represents that any
- applicable patent or other IPR claims of which he or she is aware
- have been or will be disclosed, and any of which he or she becomes
- aware will be disclosed, in accordance with Section 6 of BCP 79.
-
- Internet-Drafts are working documents of the Internet Engineering
- Task Force (IETF), its areas, and its working groups. Note that
- other groups may also distribute working documents as Internet-
- Drafts.
-
- Internet-Drafts are draft documents valid for a maximum of six months
- and may be updated, replaced, or obsoleted by other documents at any
- time. It is inappropriate to use Internet-Drafts as reference
- material or to cite them other than as "work in progress."
-
- The list of current Internet-Drafts can be accessed at
- http://www.ietf.org/ietf/1id-abstracts.txt.
-
- The list of Internet-Draft Shadow Directories can be accessed at
- http://www.ietf.org/shadow.html.
-
- This Internet-Draft will expire on December 18, 2006.
-
-Copyright Notice
-
- Copyright (C) The Internet Society (2006).
-
-Abstract
-
- This document describes a RTP payload format for transporting Theora
- encoded video. It details the RTP encapsulation mechanism for raw
- Theora data and configuration headers necessary to configure the
- decoder.
-
- Also included within the document are the necessary details for the
- use of Theora with MIME and Session Description Protocol (SDP).
-
-Editors Note
-
-
-
-Barbato Expires December 18, 2006 [Page 1]
-
-Internet-Draft draft-barbato-avt-rtp-theora-01 June 2006
-
-
- All references to RFC XXXX are to be replaced by references to the
- RFC number of this memo, when published.
-
-
-Table of Contents
-
- 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
- 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
- 2. Payload Format . . . . . . . . . . . . . . . . . . . . . . . . 4
- 2.1. RTP Header . . . . . . . . . . . . . . . . . . . . . . . . 4
- 2.2. Payload Header . . . . . . . . . . . . . . . . . . . . . . 5
- 2.3. Payload Data . . . . . . . . . . . . . . . . . . . . . . . 6
- 2.4. Example RTP Packet . . . . . . . . . . . . . . . . . . . . 7
- 3. Configuration Headers . . . . . . . . . . . . . . . . . . . . 8
- 3.1. In-band Header Transmission . . . . . . . . . . . . . . . 9
- 3.1.1. Packed Configuration . . . . . . . . . . . . . . . . . 9
- 3.2. Out of Band Transmission . . . . . . . . . . . . . . . . . 10
- 3.2.1. Packed Headers . . . . . . . . . . . . . . . . . . . . 11
- 3.3. Loss of Configuration Headers . . . . . . . . . . . . . . 13
- 4. Comment Headers . . . . . . . . . . . . . . . . . . . . . . . 13
- 5. Frame Packetizing . . . . . . . . . . . . . . . . . . . . . . 14
- 5.1. Example Fragmented Theora Packet . . . . . . . . . . . . . 15
- 5.2. Packet Loss . . . . . . . . . . . . . . . . . . . . . . . 17
- 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18
- 6.1. Mapping MIME Parameters into SDP . . . . . . . . . . . . . 19
- 6.1.1. SDP Example . . . . . . . . . . . . . . . . . . . . . 20
- 6.2. Usage with the SDP Offer/Answer Model . . . . . . . . . . 20
- 7. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
- 7.1. Stream Video . . . . . . . . . . . . . . . . . . . . . . . 21
- 8. Security Considerations . . . . . . . . . . . . . . . . . . . 21
- 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 22
- 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 22
- 10.1. Normative References . . . . . . . . . . . . . . . . . . . 22
- 10.2. Informative References . . . . . . . . . . . . . . . . . . 23
- Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 24
- Intellectual Property and Copyright Statements . . . . . . . . . . 25
-
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-Barbato Expires December 18, 2006 [Page 2]
-
-Internet-Draft draft-barbato-avt-rtp-theora-01 June 2006
-
-
-1. Introduction
-
- Theora is a general purpose, lossy video codec. It is based on the
- VP3 video codec produced by On2 Technologies and has been donated to
- the Xiph.org Foundation.
-
- Theora I is a block-based lossy transform codec that utilizes an 8 x
- 8 Type-II Discrete Cosine Transform and block-based motion
- compensation. This places it in the same class of codecs as MPEG-1,
- MPEG-2, MPEG-4, and H.263. The details of how individual blocks are
- organized and how DCT coefficients are stored in the bitstream differ
- substantially from these codecs, however. Theora supports only intra
- frames (I frames in MPEG) and inter frames (P frames in MPEG).
-
- Theora provides none of its own framing, synchronization, or
- protection against transmission errors. Instead, the codec expects
- to receive a discrete sequence of data packets. Theora is a free-
- form variable bit rate (VBR) codec, and these packets have no minimum
- size, maximum size, or fixed/expected size. Theora packets are thus
- intended to be used with a transport mechanism that provides free-
- form framing, synchronization, positioning, and error correction in
- accordance with these design assumptions, such as Ogg [1] or RTP/AVP
- [3].
-
- Theora I currently supports progressive video data of arbitrary
- dimensions at a constant frame rate in one of several Y'CbCr color
- spaces. Three different chroma subsampling formats are supported:
- 4:2:0, 4:2:2, and 4:4:4. The Theora I format does not support
- interlaced material, variable frame rates, bit-depths larger than 8
- bits per component, nor alternate color spaces such as RGB or
- arbitrary multi-channel spaces. Black and white content can be
- efficiently encoded, however, because the uniform chroma planes
- compress well. Arbitrary frame size will be encoded rounding to the
- upper multiple of 16 both dimension for performance reason. The
- original width and height will be encoded in the header and the
- decoder will use this information to clip the decoded frame to the
- right dimensions.
-
- Theora is similar to the Vorbis audio [10] in that it the decoder
- reads the probability model for the entropy coder and all
- quantization parameters from special "header" packets at the start of
- the compressed data. It is therefore impossible to decode any video
- data without having previously fetched the codec info and codec setup
- headers, although Theora can initiate decode at an arbitrary intra-
- frame packet so long as the codec has been initialized with the
- associated headers.
-
-
-
-
-
-Barbato Expires December 18, 2006 [Page 3]
-
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-
-
-1.1. Terminology
-
- The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
- "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
- document are to be interpreted as described in RFC 2119 [2].
-
-
-2. Payload Format
-
- For RTP based transportation of Theora encoded video the standard RTP
- header is followed by a 4 octets payload header, then the payload
- data. The payload headers are used to associate the Theora data with
- its associated decoding codebooks as well as indicating if the
- following packet contains fragmented Theora data and/or the number of
- whole Theora data frames. The payload data contains the raw Theora
- bitstream information.
-
- For RTP based transport of Theora encoded video the standard RTP
- header is followed by a 4 octets payload header, then the payload
- data.
-
-2.1. RTP Header
-
- The format of the RTP header is specified in [3] and shown in Figure
- 1. This payload format uses the fields of the header in a manner
- consistent with that specification.
-
- 0 1 2 3
- 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- |V=2|P|X| CC |M| PT | sequence number |
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- | timestamp |
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- | synchronization source (SSRC) identifier |
- +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
- | contributing source (CSRC) identifiers |
- | ... |
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-
- Figure 1: RTP Header
-
- The RTP header begins with an octet of fields (V, P, X, and CC) to
- support specialized RTP uses (see [3] and [4] for details). For
- Theora RTP, the following values are used.
-
- Version (V): 2 bits
-
-
-
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-Barbato Expires December 18, 2006 [Page 4]
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-
- This field identifies the version of RTP. The version used by this
- specification is two (2).
-
- Padding (P): 1 bit
-
- Padding MAY be used with this payload format according to section 5.1
- of [3].
-
- Extension (X): 1 bit
-
- The Extension bit is used in accordance with [3].
-
- CSRC count (CC): 4 bits
-
- The CSRC count is used in accordance with [3].
-
- Marker (M): 1 bit
-
- The Marker bit is used in accordance with [3].
-
- Payload Type (PT): 7 bits
-
- An RTP profile for a class of applications is expected to assign a
- payload type for this format, or a dynamically allocated payload type
- SHOULD be chosen which designates the payload as Theora.
-
- Sequence number: 16 bits
-
- The sequence number increments by one for each RTP data packet sent,
- and may be used by the receiver to detect packet loss and to restore
- packet sequence. This field is detailed further in [3].
-
- Timestamp: 32 bits
-
- A timestamp representing the presentation time of the first sample of
- the first Theora packet in the RTP packet. The clock frequency MUST
- be set to 90kHz.
-
- SSRC/CSRC identifiers:
-
- These two fields, 32 bits each with one SSRC field and a maximum of
- 16 CSRC fields, are as defined in [3].
-
-2.2. Payload Header
-
- The 4 octets following the RTP Header section are the Payload Header.
- This header is split into a number of bitfields detailing the format
- of the following Payload Data packets.
-
-
-
-Barbato Expires December 18, 2006 [Page 5]
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-
- 0 1 2 3
- 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- | Configuration Ident | F |TDT|# pkts.|
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-
- +-+-+-+-+-+-+-+-+
-
- Figure 2: Payload Header
-
- Configuration Ident: 24 bits
-
- This 24 bit field is used to associate the Theora data to a decoding
- Packed Configuration.
-
- Fragment type (F): 2 bit
-
- This field is set according to the following list
-
- 0 = Not Fragmented
- 1 = Start Fragment
- 2 = Continuation Fragment
- 3 = End Fragment
-
- This field must be zero if the number of packets field is non-zero.
-
- Theora Data Type (TDT): 2 bits
-
- This field sets the packet payload type for the Theora data. There
- are currently three Theora payload types.
-
- 0 = Raw Theora payload
- 1 = Theora Packed Configuration payload
- 2 = Legacy Theora Comment payload
- 3 = Reserved
-
- The packets with a TDT of value 3 MUST be ignored
-
- The last 4 bits represent the number of complete packets in this
- payload. This provides for a maximum number of 15 Theora packets in
- the payload. If the packet contains fragmented data the number of
- packets MUST be set to 0.
-
-2.3. Payload Data
-
- Each Theora payload section starts with a two octets length header
- that is used to represent the size of the following data payload,
- followed by the raw Theora packet data.
-
-
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-Barbato Expires December 18, 2006 [Page 6]
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-
- 0 1 2 3
- 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- | Payload Length | Theora Data ..
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-
- Figure 3: Payload Data
-
- The Theora codec uses relatively unstructured raw packets containing
- binary integer fields of arbitrary width that often do not fall on an
- octet boundary. When a Theora encoder produces packets, unused space
- in the last byte of a packet is always zeroed during the encoding
- process. Thus, should this unused space be read, it will return
- binary zeros.
-
- For payloads which consist of multiple Theora packets the payload
- data consists of the payload length field followed by the first
- Theora packet's data, then the payload length followed by the second
- Theora packet, and so on for each of the Theora packets in the
- payload.
-
-2.4. Example RTP Packet
-
- Here is an example RTP packet containing two Theora packets.
-
- RTP Packet Header:
-
- 0 1 2 3
- 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- | 2 |0|0| 0 |0| PT | sequence number |
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- | timestamp |
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- | synchronisation source (SSRC) identifier |
- +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
- | contributing source (CSRC) identifiers |
- | ... |
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-
- Figure 4: Example RTP Packet
-
- Payload Data:
-
-
-
-
-
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-Barbato Expires December 18, 2006 [Page 7]
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- 0 1 2 3
- 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- | Configuration Ident | 0 | 0 | 2 pks |
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- | Payload Length | ..
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- .. Theora data ..
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- .. data | Payload Length |
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- .. Theora data |
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-
- Figure 5: Example Theora Payload Packet
-
- The payload portion of the packet begins with the 24 bit
- Configuration ident field followed by 8 bits describing the payload.
- The Fragment type field is set to 0, indicating that this packet
- contains whole Theora frame data. The Data type field is set to 0
- since it is theora raw data. The number of whole Theora data packets
- is set to 2.
-
- Each of the payload blocks starts with the two octets length field
- followed by the variable length Theora packet data.
-
-
-3. Configuration Headers
-
- To decode a Theora stream three configuration header packets are
- needed. The first, called the Identification Header, indicates the
- frame dimensions, quality, blocks used and the version of the Theora
- encoder used. The second, called the Comment Header, contains stream
- metadata and the third, called the Setup Header, contains details of
- the dequantization and Huffman tables.
-
- Since this information must be transmitted reliably, and as the RTP
- stream may change certain configuration data mid-session, there are
- different methods for delivering this configuration data to a client,
- both in-band and out-of-band which are detailed below. SDP delivery
- is used to set up an initial state for the client application. The
- changes may be due to different dequantization and Huffman tables as
- well as different bitrates of the stream.
-
- The delivery vectors in use are specified by an SDP attribute to
- indicate the method and the optional URI where the Theora Packed
- Configuration (Section 3.1.1) Packets could be fetched. Different
- delivery methods MAY be advertised for the same session. The in-band
-
-
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-Barbato Expires December 18, 2006 [Page 8]
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-
- codebook delivery SHOULD be considered as baseline, out-of-band
- delivery methods that don't use RTP will not be described in this
- document. For non chained streams, the Configuration delivery method
- RECOMMENDED is inline the Packed Configuration (Section 3.1.1) in the
- SDP as explained in the IANA considerations (Section 6.1)
-
- The 24 bit Ident field is used to map which Configuration will be
- used to decode a packet. When the Ident field changes, it indicates
- that a change in the stream has taken place. The client application
- MUST have in advance the correct configuration and if the client
- detects a change in the Ident value and does not have this
- information it MUST NOT decode the raw data associated until it
- fetches the correct Configuration.
-
-3.1. In-band Header Transmission
-
- The Packed Configuration (Section 3.1.1) Payload is sent in-band with
- the packet type bits set to match the payload type. Clients MUST be
- capable of dealing with periodic re-transmission of the configuration
- headers.
-
-3.1.1. Packed Configuration
-
- A Theora Packed Configuration is indicated with the payload type
- field set to 1. Of the three headers, defined in the Theora I
- specification [16], the identification and the setup will be packed
- together, the comment header is completely suppressed. It is up to
- the client to provide a minimal size comment header to the decoder if
- required by the implementation.
-
-
-
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-Barbato Expires December 18, 2006 [Page 9]
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-
- 0 1 2 3
- 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- |V=2|P|X| CC |M| PT | xxxx |
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- | xxxxx |
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- | synchronization source (SSRC) identifier |
- +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
- | contributing source (CSRC) identifiers |
- | ... |
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- | Configuration Ident | 0 | 1 | 1|
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- | length | Identification ..
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- .. Identification ..
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- .. Identification ..
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- .. Identification |
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- .. | Setup ..
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- .. Setup ..
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- .. Setup |
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-
- Figure 6: Packed Configuration Figure
-
- The Ident field is set with the value that will be used by the Raw
- Payload Packets to address this Configuration. The Fragment type is
- set to 0 since the packet bears the full Packed configuration, the
- number of packet is set to 1. In practice, Packed Headers usually
- need to be fragmented to fit the path MTU.
-
-3.2. Out of Band Transmission
-
- This section, as stated above, does not cover all the possible out-
- of-band delivery methods since they rely on different protocols and
- be linked to specific applications. The following packet definition
- SHOULD be used in out-of-band delivery and MUST be used when
- Configuration is inlined in the SDP.
-
-
-
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-3.2.1. Packed Headers
-
- As mentioned above, the recommended delivery vector for Theora
- configuration data is via a retrieval method that can be performed
- using a reliable transport protocol. As the RTP headers are not
- required for this method of delivery the structure of the
- configuration data is slightly different. The packed header starts
- with a 32 bit count field which details the number of packed headers
- that are contained in the bundle. Next is the Packed header payload
- for each setup id.
-
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- | Number of packed headers |
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- | Packed header |
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- | Packed header |
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-
- Figure 7: Packed Headers Overview
-
- Since the Configuration Ident and the Identification Header are fixed
- length there is only a 16bit Length tag to define the length of the
- packed headers.
-
- 0 1 2 3
- 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- | Configuration Ident | ..
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- .. Length | Identification Header ..
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- .. Identification Header |
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- | Setup Header ..
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- .. Setup Header |
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-
- Figure 8: Packed Headers Detail
-
- The key difference from the in-band format is that there is no need
- for the payload header octet.
-
-
-
-
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-3.2.1.1. Packed Headers IANA Considerations
-
- The following IANA considerations MUST only be applied to the packed
- headers.
-
- MIME media type name: audio
-
- MIME subtype: theora-config
-
- Required Parameters:
-
- None
-
- Optional Parameters:
-
- None
-
- Encoding considerations:
-
- This media type contains binary data.
-
- Security Considerations:
-
- See Section 6 of RFC XXXX.
-
- Interoperability considerations:
-
- None
-
- Published specification:
-
- RFC XXXX [RFC Editor: please replace by the RFC number of this
- memo, when published]
-
- Applications which use this media type:
-
- Theora encoded video, configuration data.
-
- Additional information:
-
- None
-
- Person & email address to contact for further information:
-
- Luca Barbato: <lu_zero at gentoo.org>
- IETF Audio/Video Transport Working Group
-
-
-
-
-
-Barbato Expires December 18, 2006 [Page 12]
-
-Internet-Draft draft-barbato-avt-rtp-theora-01 June 2006
-
-
- Intended usage: COMMON
-
- Restriction on usage:
-
- This media type does not depend on the transport.
-
- Author:
-
- Luca Barbato
-
- Change controller:
-
- IETF AVT Working Group
-
-3.3. Loss of Configuration Headers
-
- Unlike the loss of raw Theora payload data, the loss of a
- configuration header can lead to a situation where it will not be
- possible to successfully decode the stream.
-
- A loss of a Configuration Packet results in the halting of stream
- decoding and SHOULD be reported to the client as well as a loss
- report sent via RTCP.
-
-
-4. Comment Headers
-
- When the payload type is set to 2, the packet contains the comment
- metadata, such as artist name, track title and so on. These metadata
- messages are not intended to be fully descriptive but to offer basic
- title information. Clients MAY ignore them completely. The details
- on the format of the comments can be found in the Theora
- documentation [16].
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-Barbato Expires December 18, 2006 [Page 13]
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-
-
- 0 1 2 3
- 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- |V=2|P|X| CC |M| PT | xxxx |
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- | xxxxx |
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- | synchronization source (SSRC) identifier |
- +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
- | contributing source (CSRC) identifiers |
- | ... |
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- | Configuration Ident | 0 | 2 | 1|
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- | length | Comment ..
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- .. Comment ..
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- .. Comment |
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-
- Figure 9: Comment Packet
-
- The 2 byte length field is necessary since this Theora packet could
- be fragmented.
-
-
-5. Frame Packetizing
-
- Each RTP packet contains either one complete Theora packet, one
- Theora packet fragment, or an integer number of complete Theora
- packets (up to a maximum of 15 packets, since the number of packets
- is defined by a 4 bit value).
-
- Any Theora data packet that is less than path MTU SHOULD be bundled
- in the RTP packet with as many Theora packets as will fit, up to a
- maximum of 15. Path MTU is detailed in [7] and [8].
-
- A fragmented packet has a zero in the last four bits of the payload
- header. The RTP packet containing the first fragment will set the
- Fragment type to 1. Each RTP packet after the first will set the
- Fragment type to 2 in the payload header. The RTP packet containing
- the last fragment of the Theora packet will have the Fragment type
- set to 3. If the fragmented Theora packet spans only two RTP
- packets, the first will set the Fragment type field to 1 and the
- second will set it to 2. To maintain the correct sequence for
- fragmented packet reception the timestamp field of fragmented packets
-
-
-
-Barbato Expires December 18, 2006 [Page 14]
-
-Internet-Draft draft-barbato-avt-rtp-theora-01 June 2006
-
-
- MUST be the same as the first packet sent, with the sequence number
- incremented as normal for the subsequent RTP packets.
-
-5.1. Example Fragmented Theora Packet
-
- Here is an example fragmented Theora packet split over three RTP
- packets. Each packet contains the standard RTP headers as well as
- the 4 octets Theora headers.
-
- Packet 1:
-
- 0 1 2 3
- 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- |V=2|P|X| CC |M| PT | 1000 |
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- | xxxxx |
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- | synchronization source (SSRC) identifier |
- +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
- | contributing source (CSRC) identifiers |
- | ... |
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- | Configuration Ident | 1 | 0 | 0|
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- | Payload Length | Theora data ..
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- .. Theora data ..
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-
- Figure 10: Example Fragmented Packet (Packet 1)
-
- In this packet the initial sequence number is 1000 and the timestamp
- is xxxxx. The Fragment type field is set to one, indicating it is
- the start packet of a serie of fragments. The number of packets
- field is set to 0, and as the payload is raw Theora data the Theora
- payload type field is set to 0.
-
-
-
-
-
-
-
-
-
-
-
-
-
-Barbato Expires December 18, 2006 [Page 15]
-
-Internet-Draft draft-barbato-avt-rtp-theora-01 June 2006
-
-
- Packet 2:
-
- 0 1 2 3
- 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- |V=2|P|X| CC |M| PT | 1001 |
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- | xxxxx |
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- | synchronization source (SSRC) identifier |
- +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
- | contributing source (CSRC) identifiers |
- | ... |
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- | Configuration Ident | 2 | 0 | 0|
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- | Payload Length | ..
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- .. Theora data ..
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-
- Figure 11: Example Fragmented Packet (Packet 2)
-
- The Fragment type field is set to 2 and the number of packets field
- is set to 0. For large Theora fragments there can be several of
- these type of payload packets. The maximum RTP packet size SHOULD be
- no greater than the path MTU, including all RTP and payload headers.
- The sequence number has been incremented by one but the timestamp
- field remains the same as the initial packet.
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-Barbato Expires December 18, 2006 [Page 16]
-
-Internet-Draft draft-barbato-avt-rtp-theora-01 June 2006
-
-
- Packet 3:
-
- 0 1 2 3
- 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- |V=2|P|X| CC |M| PT | 1002 |
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- | xxxxx |
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- | synchronization source (SSRC) identifier |
- +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
- | contributing source (CSRC) identifiers |
- | ... |
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- | Configuration Ident | 3 | 0 | 0|
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- | Payload Length | ..
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- .. Theora data ..
- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-
- Figure 12: Example Fragmented Packet (Packet 3)
-
- This is the last Theora fragment packet. The Fragment type filed is
- set to 3 and the packet count remains set to 0. As in the previous
- packets the timestamp remains set to the first packet in the sequence
- and the sequence number has been incremented.
-
-5.2. Packet Loss
-
- As there is no error correction within the Theora stream, packet loss
- will result in a loss of signal. Packet loss is more of an issue for
- fragmented Theora packets as the client will have to cope with the
- handling of the Fragment type field. If we use the fragmented Theora
- packet example above and the first packet is lost the client MUST
- detect that the next packet has the packet count field set to 0 and
- the Fragment type is set to 2 and MUST drop it. The next packet,
- which is the final fragmented packet, MUST be dropped in the same
- manner. Feedback reports on lost and dropped packets MUST be sent
- back via RTCP.[note: reordering]
-
- If a particular multicast session has a large number of participants
- care must be taken to prevent an RTCP feedback implosion, [9], in the
- event of packet loss from a large number of participants.
-
- Loss of any of the Configuration fragment will result in the loss of
- the full Configuration packet as detailed in the Loss of
-
-
-
-Barbato Expires December 18, 2006 [Page 17]
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-
-
- Configuration Headers (Section 3.3) section.
-
-
-6. IANA Considerations
-
- MIME media type name: video
-
- MIME subtype: theora
-
- Required Parameters:
-
- sampling: Determines the chroma subsampling format.
-
- width: Determines the number of pixels per line. This is an
- integer between 1 and 1048561 and MUST be in multiples of 16.
-
- height: Determines the number of lines per frame encoded. This is
- an integer between 1 and 1048561 and MUST be in multiples of
- 16.
-
- delivery-method: indicates the delivery methods in use, the
- possible values are: inline, in_band, out_band/specific_name
- Where "specific_name" is the name of the out of band delivery
- method.
-
- configuration: the base16 [11] (hexadecimal) representation of the
- Packed Headers (Section 3.2.1).
-
- Optional Parameters:
-
- configuration-uri: the URI of the configuration headers in case of
- out of band transmission. In the form of
- "protocol://path/to/resource/". Depending on the specific
- method the single ident packets could be retrived by their
- number or aggregated in a single stream, aggregates MAY be
- compressed using gzip [12] or bzip2 [14] and an sha1 [13]
- checksum MAY be provided in the form of
- "protocol://path/to/resource/aggregated.bz2!sha1hash"
-
- Encoding considerations:
-
- This media type is framed and contains binary data.
-
- Security Considerations:
-
- See Section 6 of RFC XXXX.
-
-
-
-
-
-Barbato Expires December 18, 2006 [Page 18]
-
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-
-
- Interoperability considerations:
-
- None
-
- Published specification:
-
- RFC XXXX [RFC Editor: please replace by the RFC number of this
- memo, when published]
-
- Ogg Theora I specification: Codec setup and packet decode.
- Available from the Xiph website, http://www.xiph.org
-
- Applications which use this media type:
-
- Audio streaming and conferencing tools
-
- Additional information:
-
- None
-
- Person & email address to contact for further information:
-
- Luca Barbato: <lu_zero at gentoo.org>
- IETF Audio/Video Transport Working Group
-
- Intended usage:
-
- COMMON
-
- Restriction on usage:
-
- This media type depends on RTP framing, and hence is only defined
- for transfer via RTP [3]
-
- Author:
-
- Luca Barbato
-
- Change controller:
-
- IETF AVT Working Group
-
-
-6.1. Mapping MIME Parameters into SDP
-
- The information carried in the MIME media type specification has a
- specific mapping to fields in the Session Description Protocol (SDP)
- [6], which is commonly used to describe RTP sessions. When SDP is
-
-
-
-Barbato Expires December 18, 2006 [Page 19]
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-
-
- used to specify sessions the mapping are as follows:
-
- o The MIME type ("video") goes in SDP "m=" as the media name.
-
- o The MIME subtype ("theora") goes in SDP "a=rtpmap" as the encoding
- name.
-
- o The clock rate in the "a=rtpmap" line MUST be 90000
-
- o The mandated parameters "delivery-method" and "configuration" MUST
- be included in the SDP "a=fmpt" attribute.
-
- o The optional parameter "configuration-uri", when present, MUST be
- included in the SDP "a=fmpt" attribute and MUST follow the
- delivery-method that applies.
-
- If the stream uses multiple decoder setup configurations and all of
- them are known in advance, the Configuration Packet for each file
- SHOULD be packaged together and passed to the client using the
- configuration attribute.
-
- The URI specified in the configuration-uri attribute MUST point to a
- location where all of the Configuration Packets needed for the life
- of the session reside.
-
-6.1.1. SDP Example
-
- The following example shows a basic SDP for a single stream. The
- first configuration packet is inlined in the sdp, other
- configurations could be fetched at any time from the first provided
- uri using or all the known configuration could be downloaded using
- the second uri. The inline base16 [11] configuration string is
- omitted because of the lenght.
- c=IN IP4 192.0.0.1
- m=video RTP/AVP 98
- a=rtpmap:98 theora/90000
- a=fmtp:98 sampling=YCbCr-4:2:2; width=1280; height=720; delivery-
- method=inline; configuration=base16string1; delivery-
- method=out_band/rtsp; delivery-method=out_band/rtsp;
- configuration-uri=rtsp://path/to/resource/; delivery-
- method=out_band/http; configuration-uri=http://another/path/to/
- resource/aggregate.bz2!sha1hash;
-
-6.2. Usage with the SDP Offer/Answer Model
-
- The offer, as described in An Offer/Answer Model Session Description
- Protocol [5], may contain a large number of delivery methods per
- single fmtp attribute, the answerer MUST remove every delivery-method
-
-
-
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-
-
- and configuration-uri not supported. All the parameters MUST not be
- altered on answer otherwise.
-
-
-7. Examples
-
- The following examples are common usage patterns that MAY be applied
- in such situations, the main scope of this section is to explain
- better usage of the transmission vectors.
-
-7.1. Stream Video
-
- This is one of the most common situation: one single server streaming
- content in multicast, the clients may start a session at random time.
- The content itself could be a mix of live stream, as the wj's voice
- or studio scenes, and stored streams, as the music she plays.
-
- In this situation we don't know in advance how many codebooks we will
- use. The clients can join anytime and users expect to start the
- fruition of the content in a short time.
-
- On join the client will receive the current Configuration necessary
- to decode the current streams inlined in the SDP so that the decoding
- will start immediately after.
-
- When the streamed content changes the new Configuration is sent in-
- band before the actual stream, and the Configuration that has to be
- sent inline in the SDP updated. Since the inline method is
- unreliable, an out of band fallback is provided.
-
- The client could choose to fetch the Configuration from the alternate
- source as soon it discovers a Configuration packet got lost inline or
- use selective retransmission [17], if the server supports the
- feature.
-
- A serverside optimization would be to keep an hash list of the
- Configurations per session to avoid packing all of them and send the
- same Configuration with different Ident tags
-
- A clientside optimization would be to keep a tag list of the
- Configurations per session and don't process configuration packets
- already known.
-
-
-8. Security Considerations
-
- RTP packets using this payload format are subject to the security
- considerations discussed in the RTP specification [3]. This implies
-
-
-
-Barbato Expires December 18, 2006 [Page 21]
-
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-
-
- that the confidentiality of the media stream is achieved by using
- encryption. Because the data compression used with this payload
- format is applied end-to-end, encryption may be performed on the
- compressed data. Where the size of a data block is set care MUST be
- taken to prevent buffer overflows in the client applications.
-
-
-9. Acknowledgments
-
- This document is a continuation of draft-kerr-avt-theora-rtp-00.txt
-
- Thanks to the AVT, Ogg Theora Communities / Xiph.org, Fluendo, Ralph
- Giles, Mike Smith, Phil Kerr, Timothy Terriberry, Stefan Ehmann,
- Alessandro Salvatori, Politecnico di Torino (LS)^3/IMG Group in
- particular Federico Ridolfo, Francesco Varano, Giampaolo Mancini,
- Juan Carlos De Martin.
-
-
-10. References
-
-10.1. Normative References
-
- [1] Pfeiffer, S., "The Ogg Encapsulation Format Version 0",
- RFC 3533.
-
- [2] Bradner, S., "Key words for use in RFCs to Indicate Requirement
- Levels", RFC 2119.
-
- [3] Schulzrinne, H., Casner, S., Frederick, R., and V. Jacobson,
- "RTP: A Transport Protocol for real-time applications",
- RFC 3550.
-
- [4] Schulzrinne, H. and S. Casner, "RTP Profile for video and Video
- Conferences with Minimal Control.", RFC 3551.
-
- [5] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model with
- Session Description Protocol (SDP)", RFC 3264.
-
- [6] Handley, M. and V. Jacobson, "SDP: Session Description
- Protocol", RFC 2327.
-
- [7] Mogul et al., J., "Path MTU Discovery", RFC 1063.
-
- [8] McCann et al., J., "Path MTU Discovery for IP version 6",
- RFC 1981.
-
- [9] Ott, J., Wenger, S., Sato, N., Burmeister, C., and J. Rey,
- "Extended RTP Profile for RTCP-based Feedback (RTP/AVPF)",
-
-
-
-Barbato Expires December 18, 2006 [Page 22]
-
-Internet-Draft draft-barbato-avt-rtp-theora-01 June 2006
-
-
- Internet Draft (draft-ietf-avt-rtcp-feedback-11: Work in
- progress).
-
- [10] Barbato, L., "RTP Payload Format for Vorbis Encoded Audio -
- draft-ietf-avt-vorbis-rtp-00", Internet Draft (Work in
- progress).
-
- [11] Josefsson, S., "The Base16, Base32, and Base64 Data Encodings",
- RFC 3548.
-
- [12] Deutsch, P., "GZIP file format specification version 4.3",
- RFC 1952.
-
- [13] National Institute of Standards and Technology, "Secure Hash
- Standard", May 1993.
-
- [14] Seward, J., "libbz2 and bzip2".
-
-10.2. Informative References
-
- [15] "libTheora: Available from the Xiph website,
- http://www.xiph.org".
-
- [16] "Theora I specification: Codec setup and packet decode.
- http://www.xiph.org/theora/doc/Theora_I_spec.pdf".
-
- [17] Friedman, T., Caceres, R., and A. Clark, "RTP Control Protocol
- Extended Reports (RTCP XR)", RFC 3611, November 2003.
-
- [18] "ITU-T Recommendation V.42, 1994, Rev. 1. Error-correcting
- Procedures for DCEs Using Asynchronous-to-Synchronous
- Conversion. International Telecommunications Union. Available
- from the ITU website, http://www.itu.int".
-
- [19] "ISO 3309, October 1984, 3rd Edition. Information Processing
- Systems--Data Communication High-Level Data Link Control
- Procedure--Frame Structure. International Organization for
- Standardization.".
-
-
-
-
-
-
-
-
-
-
-
-
-
-Barbato Expires December 18, 2006 [Page 23]
-
-Internet-Draft draft-barbato-avt-rtp-theora-01 June 2006
-
-
-Author's Address
-
- Luca Barbato
- Xiph.Org
-
- Email: lu_zero at gentoo.org
- URI: http://www.xiph.org/
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-Barbato Expires December 18, 2006 [Page 24]
-
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-
-
-Intellectual Property Statement
-
- The IETF takes no position regarding the validity or scope of any
- Intellectual Property Rights or other rights that might be claimed to
- pertain to the implementation or use of the technology described in
- this document or the extent to which any license under such rights
- might or might not be available; nor does it represent that it has
- made any independent effort to identify any such rights. Information
- on the procedures with respect to rights in RFC documents can be
- found in BCP 78 and BCP 79.
-
- Copies of IPR disclosures made to the IETF Secretariat and any
- assurances of licenses to be made available, or the result of an
- attempt made to obtain a general license or permission for the use of
- such proprietary rights by implementers or users of this
- specification can be obtained from the IETF on-line IPR repository at
- http://www.ietf.org/ipr.
-
- The IETF invites any interested party to bring to its attention any
- copyrights, patents or patent applications, or other proprietary
- rights that may cover technology that may be required to implement
- this standard. Please address the information to the IETF at
- ietf-ipr at ietf.org.
-
-
-Disclaimer of Validity
-
- This document and the information contained herein are provided on an
- "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
- OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
- ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
- INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
- INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
- WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
-
-
-Copyright Statement
-
- Copyright (C) The Internet Society (2006). This document is subject
- to the rights, licenses and restrictions contained in BCP 78, and
- except as set forth therein, the authors retain all their rights.
-
-
-Acknowledgment
-
- Funding for the RFC Editor function is currently provided by the
- Internet Society.
-
-
-
-
-Barbato Expires December 18, 2006 [Page 25]
-
-
Added: trunk/theora/doc/draft-ietf-avt-rtp-theora-00.txt
===================================================================
--- trunk/theora/doc/draft-ietf-avt-rtp-theora-00.txt 2006-07-21 16:53:25 UTC (rev 11713)
+++ trunk/theora/doc/draft-ietf-avt-rtp-theora-00.txt 2006-07-21 17:09:30 UTC (rev 11714)
@@ -0,0 +1,1400 @@
+
+
+
+AVT Working Group L. Barbato
+Internet-Draft Xiph.Org
+Expires: January 22, 2007 July 21, 2006
+
+
+ draft-ietf-avt-rtp-theora-00
+ RTP Payload Format for Theora Encoded Video
+
+Status of this Memo
+
+ By submitting this Internet-Draft, each author represents that any
+ applicable patent or other IPR claims of which he or she is aware
+ have been or will be disclosed, and any of which he or she becomes
+ aware will be disclosed, in accordance with Section 6 of BCP 79.
+
+ Internet-Drafts are working documents of the Internet Engineering
+ Task Force (IETF), its areas, and its working groups. Note that
+ other groups may also distribute working documents as Internet-
+ Drafts.
+
+ Internet-Drafts are draft documents valid for a maximum of six months
+ and may be updated, replaced, or obsoleted by other documents at any
+ time. It is inappropriate to use Internet-Drafts as reference
+ material or to cite them other than as "work in progress."
+
+ The list of current Internet-Drafts can be accessed at
+ http://www.ietf.org/ietf/1id-abstracts.txt.
+
+ The list of Internet-Draft Shadow Directories can be accessed at
+ http://www.ietf.org/shadow.html.
+
+ This Internet-Draft will expire on January 22, 2007.
+
+Copyright Notice
+
+ Copyright (C) The Internet Society (2006).
+
+Abstract
+
+ This document describes a RTP payload format for transporting Theora
+ encoded video. It details the RTP encapsulation mechanism for raw
+ Theora data and configuration headers necessary to configure the
+ decoder.
+
+ Also included within the document are the necessary details for the
+ use of Theora with MIME and Session Description Protocol (SDP).
+
+Editors Note
+
+
+
+Barbato Expires January 22, 2007 [Page 1]
+
+Internet-Draft draft-ietf-avt-rtp-theora-00 July 2006
+
+
+ All references to RFC XXXX are to be replaced by references to the
+ RFC number of this memo, when published.
+
+
+Table of Contents
+
+ 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
+ 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
+ 2. Payload Format . . . . . . . . . . . . . . . . . . . . . . . . 4
+ 2.1. RTP Header . . . . . . . . . . . . . . . . . . . . . . . . 4
+ 2.2. Payload Header . . . . . . . . . . . . . . . . . . . . . . 5
+ 2.3. Payload Data . . . . . . . . . . . . . . . . . . . . . . . 6
+ 2.4. Example RTP Packet . . . . . . . . . . . . . . . . . . . . 7
+ 3. Configuration Headers . . . . . . . . . . . . . . . . . . . . 8
+ 3.1. In-band Header Transmission . . . . . . . . . . . . . . . 9
+ 3.1.1. Packed Configuration . . . . . . . . . . . . . . . . . 9
+ 3.2. Out of Band Transmission . . . . . . . . . . . . . . . . . 10
+ 3.2.1. Packed Headers . . . . . . . . . . . . . . . . . . . . 11
+ 3.3. Loss of Configuration Headers . . . . . . . . . . . . . . 13
+ 4. Comment Headers . . . . . . . . . . . . . . . . . . . . . . . 13
+ 5. Frame Packetizing . . . . . . . . . . . . . . . . . . . . . . 14
+ 5.1. Example Fragmented Theora Packet . . . . . . . . . . . . . 15
+ 5.2. Packet Loss . . . . . . . . . . . . . . . . . . . . . . . 17
+ 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18
+ 6.1. Mapping MIME Parameters into SDP . . . . . . . . . . . . . 19
+ 6.1.1. SDP Example . . . . . . . . . . . . . . . . . . . . . 20
+ 6.2. Usage with the SDP Offer/Answer Model . . . . . . . . . . 20
+ 7. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
+ 7.1. Stream Video . . . . . . . . . . . . . . . . . . . . . . . 21
+ 8. Security Considerations . . . . . . . . . . . . . . . . . . . 21
+ 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 22
+ 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 22
+ 10.1. Normative References . . . . . . . . . . . . . . . . . . . 22
+ 10.2. Informative References . . . . . . . . . . . . . . . . . . 23
+ Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 24
+ Intellectual Property and Copyright Statements . . . . . . . . . . 25
+
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+Internet-Draft draft-ietf-avt-rtp-theora-00 July 2006
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+1. Introduction
+
+ Theora is a general purpose, lossy video codec. It is based on the
+ VP3 video codec produced by On2 Technologies and has been donated to
+ the Xiph.org Foundation.
+
+ Theora I is a block-based lossy transform codec that utilizes an 8 x
+ 8 Type-II Discrete Cosine Transform and block-based motion
+ compensation. This places it in the same class of codecs as MPEG-1,
+ MPEG-2, MPEG-4, and H.263. The details of how individual blocks are
+ organized and how DCT coefficients are stored in the bitstream differ
+ substantially from these codecs, however. Theora supports only intra
+ frames (I frames in MPEG) and inter frames (P frames in MPEG).
+
+ Theora provides none of its own framing, synchronization, or
+ protection against transmission errors. Instead, the codec expects
+ to receive a discrete sequence of data packets. Theora is a free-
+ form variable bit rate (VBR) codec, and these packets have no minimum
+ size, maximum size, or fixed/expected size. Theora packets are thus
+ intended to be used with a transport mechanism that provides free-
+ form framing, synchronization, positioning, and error correction in
+ accordance with these design assumptions, such as Ogg [1] or RTP/AVP
+ [3].
+
+ Theora I currently supports progressive video data of arbitrary
+ dimensions at a constant frame rate in one of several Y'CbCr color
+ spaces. Three different chroma subsampling formats are supported:
+ 4:2:0, 4:2:2, and 4:4:4. The Theora I format does not support
+ interlaced material, variable frame rates, bit-depths larger than 8
+ bits per component, nor alternate color spaces such as RGB or
+ arbitrary multi-channel spaces. Black and white content can be
+ efficiently encoded, however, because the uniform chroma planes
+ compress well. For performance reason, arbitrary frame sizes will be
+ encoded rounding both dimensions to the upper multiple of 16. The
+ original width and height will be encoded in the header and the
+ decoder will use this information to clip the decoded frame to the
+ right dimensions.
+
+ Theora is similar to the Vorbis audio [10] in that the decoder reads
+ the probability model for the entropy coder and all quantization
+ parameters from special "header" packets at the start of the
+ compressed data. It is therefore impossible to decode any video data
+ without having previously fetched the codec info and codec setup
+ headers, although Theora can begin to decode at an arbitrary intra-
+ frame packet so long as the codec has been initialized with the
+ associated headers.
+
+
+
+
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+1.1. Terminology
+
+ The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
+ "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
+ document are to be interpreted as described in RFC 2119 [2].
+
+
+2. Payload Format
+
+ For RTP based transportation of Theora encoded video the standard RTP
+ header is followed by a 4 octets payload header, then the payload
+ data. The payload headers are used to associate the Theora data with
+ its associated decoding codebooks as well as indicating if the
+ following packet contains fragmented Theora data and/or the number of
+ whole Theora data frames. The payload data contains the raw Theora
+ bitstream information.
+
+ For RTP based transport of Theora encoded video the standard RTP
+ header is followed by a 4 octets payload header, then the payload
+ data.
+
+2.1. RTP Header
+
+ The format of the RTP header is specified in [3] and shown in Figure
+ 1. This payload format uses the fields of the header in a manner
+ consistent with that specification.
+
+ 0 1 2 3
+ 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ |V=2|P|X| CC |M| PT | sequence number |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | timestamp |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | synchronization source (SSRC) identifier |
+ +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
+ | contributing source (CSRC) identifiers |
+ | ... |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+ Figure 1: RTP Header
+
+ The RTP header begins with an octet of fields (V, P, X, and CC) to
+ support specialized RTP uses (see [3] and [4] for details). For
+ Theora RTP, the following values are used.
+
+ Version (V): 2 bits
+
+
+
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+ This field identifies the version of RTP. The version used by this
+ specification is two (2).
+
+ Padding (P): 1 bit
+
+ Padding MAY be used with this payload format according to section 5.1
+ of [3].
+
+ Extension (X): 1 bit
+
+ The Extension bit is used in accordance with [3].
+
+ CSRC count (CC): 4 bits
+
+ The CSRC count is used in accordance with [3].
+
+ Marker (M): 1 bit
+
+ The Marker bit is used in accordance with [3].
+
+ Payload Type (PT): 7 bits
+
+ An RTP profile for a class of applications is expected to assign a
+ payload type for this format, or a dynamically allocated payload type
+ SHOULD be chosen which designates the payload as Theora.
+
+ Sequence number: 16 bits
+
+ The sequence number increments by one for each RTP data packet sent,
+ and may be used by the receiver to detect packet loss and to restore
+ packet sequence. This field is detailed further in [3].
+
+ Timestamp: 32 bits
+
+ A timestamp representing the presentation time of the first sample of
+ the first Theora packet in the RTP packet. The clock frequency MUST
+ be set to 90kHz.
+
+ SSRC/CSRC identifiers:
+
+ These two fields, 32 bits each with one SSRC field and a maximum of
+ 16 CSRC fields, are as defined in [3].
+
+2.2. Payload Header
+
+ The 4 octets following the RTP Header section represent the Payload
+ Header. This header is split into a number of bitfields detailing
+ the format of the following Payload Datagrams.
+
+
+
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+ 0 1 2 3
+ 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | Configuration Ident | F |TDT|# pkts.|
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+ +-+-+-+-+-+-+-+-+
+
+ Figure 2: Payload Header
+
+ Configuration Ident: 24 bits
+
+ This 24 bit field is used to associate the Theora data to a decoding
+ Packed Configuration.
+
+ Fragment type (F): 2 bit
+
+ This field is set according to the following list
+
+ 0 = Not Fragmented
+ 1 = Start Fragment
+ 2 = Continuation Fragment
+ 3 = End Fragment
+
+ This field must be zero if the number of packets field is non-zero.
+
+ Theora Data Type (TDT): 2 bits
+
+ This field sets the packet payload type for the Theora data. There
+ are currently three Theora payload types currently used and one
+ reserved for future use.
+
+ 0 = Raw Theora payload
+ 1 = Theora Packed Configuration payload
+ 2 = Legacy Theora Comment payload
+ 3 = Reserved
+
+ The packets with a TDT of value 3 MUST be ignored
+
+ The last 4 bits represent the number of complete packets in this
+ payload. This provides a maximum number of 15 Theora packets in the
+ payload. If the packet contains fragmented data the number of
+ packets MUST be set to 0.
+
+2.3. Payload Data
+
+ Each Theora payload section starts with a two octets length header
+ that is used to represent the size of the following data payload,
+
+
+
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+ followed by the raw Theora packet data.
+
+ 0 1 2 3
+ 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | Payload Length | Theora Data ..
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+ Figure 3: Payload Data
+
+ The Theora codec uses relatively unstructured raw packets containing
+ binary integer fields of arbitrary width that often do not fall on an
+ octet boundary. When a Theora encoder produces packets, unused space
+ in the last byte of a packet is always zeroed during the encoding
+ process. Thus, should this unused space be read, it will return
+ binary zeros.
+
+ For payloads which consist of multiple Theora packets the payload
+ data consists of the payload length field followed by the first
+ Theora packet's data, then the payload length followed by the second
+ Theora packet, and so on for each of the Theora packets in the
+ payload.
+
+2.4. Example RTP Packet
+
+ Here is an example RTP packet containing two Theora packets.
+
+ RTP Packet Header:
+
+ 0 1 2 3
+ 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | 2 |0|0| 0 |0| PT | sequence number |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | timestamp |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | synchronisation source (SSRC) identifier |
+ +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
+ | contributing source (CSRC) identifiers |
+ | ... |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+ Figure 4: Example RTP Packet
+
+ Payload Data:
+
+
+
+
+
+
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+ 0 1 2 3
+ 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | Configuration Ident | 0 | 0 | 2 pks |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | Payload Length | ..
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ .. Theora data ..
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ .. data | Payload Length |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ .. Theora data |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+ Figure 5: Example Theora Payload Packet
+
+ The payload portion of the packet begins with the 24 bit
+ Configuration ident field followed by 8 bits describing the payload.
+ The Fragment type field is set to 0, indicating that this packet
+ contains whole Theora frame data. The Data type field is set to 0
+ (theora raw data). The number of whole Theora data packets is set to
+ 2.
+
+ Each of the payload blocks starts with the two octets length field
+ followed by the variable length Theora packet data.
+
+
+3. Configuration Headers
+
+ To decode a Theora stream three configuration header packets are
+ needed. The first (Identification Header) indicates frame
+ dimensions, quality, blocks used and Theora encoder version. The
+ second (Comment Header) contains stream metadata and the third (Setup
+ Header) contains details of the dequantization and Huffman tables.
+
+ Since this information must be transmitted reliably, and as the RTP
+ stream may change certain configuration data mid-session, there are
+ different methods for delivering this configuration data to a client,
+ both in-band and out-of-band, which are detailed below. SDP delivery
+ is used to set up an initial state for the client application. The
+ changes may be due to different dequantization and Huffman tables as
+ well as different bitrates of the stream.
+
+ The delivery vectors in use are specified by an SDP attribute that
+ indicates the method and the optional URI where the Theora Packed
+ Configuration (Section 3.1.1) Packets could be fetched. Different
+ delivery methods MAY be advertised for the same session. The in-band
+ codebook delivery SHOULD be considered as baseline, out-of-band
+
+
+
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+ delivery methods that don't use RTP will not be described in this
+ document. For non chained streams, the RECOMMENDED Configuration
+ delivery method is inline the Packed Configuration (Section 3.1.1) in
+ the SDP as explained in the IANA considerations (Section 6.1)
+
+ The 24 bit Ident field is used to map which Configuration will be
+ used to decode a packet. When the Ident field changes, it indicates
+ that a change in the stream has taken place. The client application
+ MUST have in advance the correct configuration and if the client
+ detects a change in the Ident value and does not have this
+ information it MUST NOT decode the raw data associated until it has
+ fetched the correct Configuration.
+
+3.1. In-band Header Transmission
+
+ The Packed Configuration (Section 3.1.1) Payload is sent in-band with
+ the packet type bits set to match the payload type. Clients MUST be
+ capable of dealing with periodic re-transmission of the configuration
+ headers.
+
+3.1.1. Packed Configuration
+
+ A Theora Packed Configuration is identified by a payload type field
+ of 1. Of the three headers, defined in the Theora I specification
+ [16], the identification and the setup will be packed together, while
+ the comment header will be completely suppressed. It is up to the
+ client to provide a minimal size comment header to the decoder if
+ required by the implementation.
+
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+ 0 1 2 3
+ 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ |V=2|P|X| CC |M| PT | xxxx |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | xxxxx |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | synchronization source (SSRC) identifier |
+ +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
+ | contributing source (CSRC) identifiers |
+ | ... |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | Configuration Ident | 0 | 1 | 1|
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | length | Identification ..
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ .. Identification ..
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ .. Identification ..
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ .. Identification |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ .. | Setup ..
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ .. Setup ..
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ .. Setup |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+ Figure 6: Packed Configuration Figure
+
+ The Ident field is set with the value that will be used by the Raw
+ Payload Packets to address this Configuration. The Fragment type is
+ set to 0 since the packet bears full Packed configuration, the number
+ of packet is set to 1. In practice, Packed Headers usually need to
+ be fragmented to fit the path MTU.
+
+3.2. Out of Band Transmission
+
+ This section, as stated above, does not cover all the possible out-
+ of-band delivery methods since they rely on different protocols and
+ are linked to specific applications. The following packet definition
+ SHOULD be used in out-of-band delivery and MUST be used when
+ Configuration is inlined in the SDP.
+
+
+
+
+
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+3.2.1. Packed Headers
+
+ As mentioned above, the recommended delivery vector for Theora
+ configuration data is via a retrieval method that can be performed
+ using a reliable transport protocol. As the RTP headers are not
+ required for this method of delivery the structure of the
+ configuration data is slightly different. The packed header starts
+ with a 32 bit count field which details the number of packed headers
+ that are contained in the bundle. Next is the Packed header payload
+ for each setup id.
+
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | Number of packed headers |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | Packed header |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | Packed header |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+ Figure 7: Packed Headers Overview
+
+ Since the Configuration Ident and the Identification Header are fixed
+ length there is only a 16bit Length tag to define the length of the
+ packed headers.
+
+ 0 1 2 3
+ 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | Configuration Ident | ..
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ .. Length | Identification Header ..
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ .. Identification Header |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | Setup Header ..
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ .. Setup Header |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+ Figure 8: Packed Headers Detail
+
+ The key difference from the in-band format is that there is no need
+ for the payload header octet.
+
+
+
+
+
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+3.2.1.1. Packed Headers IANA Considerations
+
+ The following IANA considerations MUST only be applied to the packed
+ headers.
+
+ MIME media type name: audio
+
+ MIME subtype: theora-config
+
+ Required Parameters:
+
+ None
+
+ Optional Parameters:
+
+ None
+
+ Encoding considerations:
+
+ This media type contains binary data.
+
+ Security Considerations:
+
+ See Section 6 of RFC XXXX.
+
+ Interoperability considerations:
+
+ None
+
+ Published specification:
+
+ RFC XXXX [RFC Editor: please replace by the RFC number of this
+ memo, when published]
+
+ Applications which use this media type:
+
+ Theora encoded video, configuration data.
+
+ Additional information:
+
+ None
+
+ Person & email address to contact for further information:
+
+ Luca Barbato: <lu_zero at gentoo.org>
+ IETF Audio/Video Transport Working Group
+
+
+
+
+
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+
+ Intended usage: COMMON
+
+ Restriction on usage:
+
+ This media type does not depend on the transport.
+
+ Author:
+
+ Luca Barbato
+
+ Change controller:
+
+ IETF AVT Working Group
+
+3.3. Loss of Configuration Headers
+
+ Unlike the loss of raw Theora payload data, the loss of a
+ configuration header can lead to a situation where it will not be
+ possible to successfully decode the stream.
+
+ A loss of a Configuration Packet causes the stream decoder to halt
+ and SHOULD be reported to the client as well as a loss report sent
+ via RTCP.
+
+
+4. Comment Headers
+
+ When the payload type is set to 2, the packet contains comment
+ metadata such as artist name, track title and so on. These metadata
+ messages are not intended to be fully descriptive but to offer basic
+ title information. Clients MAY choose to completely ignore them.
+ The details on the comments format can be found in the Theora
+ documentation [16].
+
+
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+ 0 1 2 3
+ 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ |V=2|P|X| CC |M| PT | xxxx |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | xxxxx |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | synchronization source (SSRC) identifier |
+ +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
+ | contributing source (CSRC) identifiers |
+ | ... |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | Configuration Ident | 0 | 2 | 1|
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | length | Comment ..
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ .. Comment ..
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ .. Comment |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+ Figure 9: Comment Packet
+
+ The 2 byte length field is necessary since this Theora packet could
+ be fragmented.
+
+
+5. Frame Packetizing
+
+ Each RTP packet contains either one complete Theora packet, one
+ Theora packet fragment, or an integer number of complete Theora
+ packets (up to a maximum of 15 packets, since the number of packets
+ is defined by a 4 bit value).
+
+ Any Theora data packet that is less than path MTU SHOULD be bundled
+ in the RTP packet with as many Theora packets as will fit, up to a
+ maximum of 15. Path MTU is detailed in [7] and [8].
+
+ A fragmented packet has a zero in the last four bits of the payload
+ header. The RTP packet containing the first fragment will set the
+ Fragment type to 1. Each RTP packet after the first will set the
+ Fragment type to 2 in the payload header. The RTP packet containing
+ the last fragment of the Theora packet will have the Fragment type
+ set to 3. If the fragmented Theora packet spans only two RTP
+ packets, the first will set the Fragment type field to 1 and the
+ second will set it to 2. To maintain the correct sequence for
+ fragmented packet reception the timestamp field of fragmented packets
+
+
+
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+
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+
+
+ MUST be the same as the first packet sent, with the sequence number
+ incremented as normal for the subsequent RTP packets.
+
+5.1. Example Fragmented Theora Packet
+
+ Here is an example fragmented Theora packet split over three RTP
+ packets. Each packet contains the standard RTP headers as well as
+ the 4 octets Theora headers.
+
+ Packet 1:
+
+ 0 1 2 3
+ 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ |V=2|P|X| CC |M| PT | 1000 |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | xxxxx |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | synchronization source (SSRC) identifier |
+ +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
+ | contributing source (CSRC) identifiers |
+ | ... |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | Configuration Ident | 1 | 0 | 0|
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | Payload Length | Theora data ..
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ .. Theora data ..
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+ Figure 10: Example Fragmented Packet (Packet 1)
+
+ In this packet the initial sequence number is 1000 and the timestamp
+ is xxxxx. The Fragment type field is set to one, indicating it is
+ the start packet of a serie of fragments. The number of packets
+ field is set to 0, and as the payload is raw Theora data the Theora
+ payload type field is set to 0.
+
+
+
+
+
+
+
+
+
+
+
+
+
+Barbato Expires January 22, 2007 [Page 15]
+
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+
+
+ Packet 2:
+
+ 0 1 2 3
+ 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ |V=2|P|X| CC |M| PT | 1001 |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | xxxxx |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | synchronization source (SSRC) identifier |
+ +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
+ | contributing source (CSRC) identifiers |
+ | ... |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | Configuration Ident | 2 | 0 | 0|
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | Payload Length | ..
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ .. Theora data ..
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+ Figure 11: Example Fragmented Packet (Packet 2)
+
+ The Fragment type field is set to 2 and the number of packets field
+ is set to 0. For large Theora fragments there can be several of
+ these type of payload packets. The maximum RTP packet size SHOULD be
+ no greater than the path MTU, including all RTP and payload headers.
+ The sequence number has been incremented by one but the timestamp
+ field remains the same as the initial packet.
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Barbato Expires January 22, 2007 [Page 16]
+
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+
+
+ Packet 3:
+
+ 0 1 2 3
+ 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ |V=2|P|X| CC |M| PT | 1002 |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | xxxxx |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | synchronization source (SSRC) identifier |
+ +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
+ | contributing source (CSRC) identifiers |
+ | ... |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | Configuration Ident | 3 | 0 | 0|
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ | Payload Length | ..
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ .. Theora data ..
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+ Figure 12: Example Fragmented Packet (Packet 3)
+
+ This is the last Theora fragment packet. The Fragment type filed is
+ set to 3 and the packet count remains set to 0. As in the previous
+ packets the timestamp remains set to the first packet in the sequence
+ and the sequence number has been incremented.
+
+5.2. Packet Loss
+
+ As there is no error correction within the Theora stream, packet loss
+ will result in a loss of signal. Packet loss is more of an issue for
+ fragmented Theora packets as the client will have to cope with the
+ handling of the Fragment type field. If we use the fragmented Theora
+ packet example above and the first packet is lost the client MUST
+ detect that the next packet has the packet count field set to 0 and
+ the Fragment type is set to 2 and MUST drop it. The next packet,
+ which is the final fragmented packet, MUST be dropped in the same
+ manner. Feedback reports on lost and dropped packets MUST be sent
+ back via RTCP.[note: reordering]
+
+ If a particular multicast session has a large number of participants
+ care must be taken to prevent an RTCP feedback implosion, [9], in the
+ event of packet loss from a large number of participants.
+
+ Loss of any of the Configuration fragment will result in the loss of
+ the full Configuration packet as detailed in the Loss of
+
+
+
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+
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+
+
+ Configuration Headers (Section 3.3) section.
+
+
+6. IANA Considerations
+
+ MIME media type name: video
+
+ MIME subtype: theora
+
+ Required Parameters:
+
+ sampling: Determines the chroma subsampling format.
+
+ width: Determines the number of pixels per line. This is an
+ integer between 1 and 1048561 and MUST be in multiples of 16.
+
+ height: Determines the number of lines per frame encoded. This is
+ an integer between 1 and 1048561 and MUST be in multiples of
+ 16.
+
+ delivery-method: indicates the delivery methods in use, the
+ possible values are: inline, in_band, out_band/specific_name
+ Where "specific_name" is the name of the out of band delivery
+ method.
+
+ configuration: the base16 [11] (hexadecimal) representation of the
+ Packed Headers (Section 3.2.1).
+
+ Optional Parameters:
+
+ configuration-uri: the URI of the configuration headers in case of
+ out of band transmission. In the form of
+ "protocol://path/to/resource/". Depending on the specific
+ method the single ident packets could be retrived by their
+ number or aggregated in a single stream, aggregates MAY be
+ compressed using gzip [12] or bzip2 [14] and an sha1 [13]
+ checksum MAY be provided in the form of
+ "protocol://path/to/resource/aggregated.bz2!sha1hash"
+
+ Encoding considerations:
+
+ This media type is framed and contains binary data.
+
+ Security Considerations:
+
+ See Section 6 of RFC XXXX.
+
+
+
+
+
+Barbato Expires January 22, 2007 [Page 18]
+
+Internet-Draft draft-ietf-avt-rtp-theora-00 July 2006
+
+
+ Interoperability considerations:
+
+ None
+
+ Published specification:
+
+ RFC XXXX [RFC Editor: please replace by the RFC number of this
+ memo, when published]
+
+ Ogg Theora I specification: Codec setup and packet decode.
+ Available from the Xiph website, http://www.xiph.org
+
+ Applications which use this media type:
+
+ Audio streaming and conferencing tools
+
+ Additional information:
+
+ None
+
+ Person & email address to contact for further information:
+
+ Luca Barbato: <lu_zero at gentoo.org>
+ IETF Audio/Video Transport Working Group
+
+ Intended usage:
+
+ COMMON
+
+ Restriction on usage:
+
+ This media type depends on RTP framing, and hence is only defined
+ for transfer via RTP [3]
+
+ Author:
+
+ Luca Barbato
+
+ Change controller:
+
+ IETF AVT Working Group
+
+
+6.1. Mapping MIME Parameters into SDP
+
+ The information carried in the MIME media type specification has a
+ specific mapping to fields in the Session Description Protocol (SDP)
+ [6], which is commonly used to describe RTP sessions. When SDP is
+
+
+
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+
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+
+
+ used to specify sessions the mapping are as follows:
+
+ o The MIME type ("video") goes in SDP "m=" as the media name.
+
+ o The MIME subtype ("theora") goes in SDP "a=rtpmap" as the encoding
+ name.
+
+ o The clock rate in the "a=rtpmap" line MUST be 90000
+
+ o The mandated parameters "delivery-method" and "configuration" MUST
+ be included in the SDP "a=fmpt" attribute.
+
+ o The optional parameter "configuration-uri", when present, MUST be
+ included in the SDP "a=fmpt" attribute and MUST follow the
+ delivery-method that applies.
+
+ If the stream uses multiple decoder setup configurations and all of
+ them are known in advance, the Configuration Packet for each file
+ SHOULD be packaged together and passed to the client using the
+ configuration attribute.
+
+ The URI specified in the configuration-uri attribute MUST point to a
+ location where all of the Configuration Packets needed for the life
+ of the session reside.
+
+6.1.1. SDP Example
+
+ The following example shows a basic SDP for a single stream. The
+ first configuration packet is inlined in the sdp, other
+ configurations could be fetched at any time from the first provided
+ uri using or all the known configuration could be downloaded using
+ the second uri. The inline base16 [11] configuration string is
+ omitted because of the lenght.
+ c=IN IP4 192.0.0.1
+ m=video RTP/AVP 98
+ a=rtpmap:98 theora/90000
+ a=fmtp:98 sampling=YCbCr-4:2:2; width=1280; height=720; delivery-
+ method=inline; configuration=base16string1; delivery-
+ method=out_band/rtsp; delivery-method=out_band/rtsp;
+ configuration-uri=rtsp://path/to/resource/; delivery-
+ method=out_band/http; configuration-uri=http://another/path/to/
+ resource/aggregate.bz2!sha1hash;
+
+6.2. Usage with the SDP Offer/Answer Model
+
+ The offer, as described in An Offer/Answer Model Session Description
+ Protocol [5], may contain a large number of delivery methods per
+ single fmtp attribute, the answerer MUST remove every delivery-method
+
+
+
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+
+
+ and configuration-uri not supported. All the parameters MUST not be
+ altered on answer otherwise.
+
+
+7. Examples
+
+ The following examples are common usage patterns that MAY be applied
+ in such situations, the main scope of this section is to explain
+ better usage of the transmission vectors.
+
+7.1. Stream Video
+
+ This is one of the most common situation: one single server streaming
+ content in multicast, the clients may start a session at random time.
+ The content itself could be a mix of live stream, as the wj's voice
+ or studio scenes, and stored streams, as the music she plays.
+
+ In this situation we don't know in advance how many codebooks we will
+ use. The clients can join anytime and users expect to start the
+ fruition of the content in a short time.
+
+ On join the client will receive the current Configuration necessary
+ to decode the current streams inlined in the SDP so that the decoding
+ will start immediately after.
+
+ When the streamed content changes the new Configuration is sent in-
+ band before the actual stream, and the Configuration that has to be
+ sent inline in the SDP updated. Since the inline method is
+ unreliable, an out of band fallback is provided.
+
+ The client could choose to fetch the Configuration from the alternate
+ source as soon it discovers a Configuration packet got lost inline or
+ use selective retransmission [17], if the server supports the
+ feature.
+
+ A serverside optimization would be to keep an hash list of the
+ Configurations per session to avoid packing all of them and send the
+ same Configuration with different Ident tags
+
+ A clientside optimization would be to keep a tag list of the
+ Configurations per session and don't process configuration packets
+ already known.
+
+
+8. Security Considerations
+
+ RTP packets using this payload format are subject to the security
+ considerations discussed in the RTP specification [3]. This implies
+
+
+
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+
+
+ that the confidentiality of the media stream is achieved by using
+ encryption. Because the data compression used with this payload
+ format is applied end-to-end, encryption may be performed on the
+ compressed data. Where the size of a data block is set care MUST be
+ taken to prevent buffer overflows in the client applications.
+
+
+9. Acknowledgments
+
+ This document is a continuation of draft-kerr-avt-theora-rtp-00.txt
+
+ Thanks to the AVT, Ogg Theora Communities / Xiph.org, Fluendo, Ralph
+ Giles, Mike Smith, Phil Kerr, Timothy Terriberry, Stefan Ehmann,
+ Alessandro Salvatori, Politecnico di Torino (LS)^3/IMG Group in
+ particular Federico Ridolfo, Francesco Varano, Giampaolo Mancini,
+ Juan Carlos De Martin.
+
+
+10. References
+
+10.1. Normative References
+
+ [1] Pfeiffer, S., "The Ogg Encapsulation Format Version 0",
+ RFC 3533.
+
+ [2] Bradner, S., "Key words for use in RFCs to Indicate Requirement
+ Levels", RFC 2119.
+
+ [3] Schulzrinne, H., Casner, S., Frederick, R., and V. Jacobson,
+ "RTP: A Transport Protocol for real-time applications",
+ RFC 3550.
+
+ [4] Schulzrinne, H. and S. Casner, "RTP Profile for video and Video
+ Conferences with Minimal Control.", RFC 3551.
+
+ [5] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model with
+ Session Description Protocol (SDP)", RFC 3264.
+
+ [6] Handley, M. and V. Jacobson, "SDP: Session Description
+ Protocol", RFC 2327.
+
+ [7] Mogul et al., J., "Path MTU Discovery", RFC 1063.
+
+ [8] McCann et al., J., "Path MTU Discovery for IP version 6",
+ RFC 1981.
+
+ [9] Ott, J., Wenger, S., Sato, N., Burmeister, C., and J. Rey,
+ "Extended RTP Profile for RTCP-based Feedback (RTP/AVPF)",
+
+
+
+Barbato Expires January 22, 2007 [Page 22]
+
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+
+
+ Internet Draft (draft-ietf-avt-rtcp-feedback-11: Work in
+ progress).
+
+ [10] Barbato, L., "RTP Payload Format for Vorbis Encoded Audio -
+ draft-ietf-avt-vorbis-rtp-00", Internet Draft (Work in
+ progress).
+
+ [11] Josefsson, S., "The Base16, Base32, and Base64 Data Encodings",
+ RFC 3548.
+
+ [12] Deutsch, P., "GZIP file format specification version 4.3",
+ RFC 1952.
+
+ [13] National Institute of Standards and Technology, "Secure Hash
+ Standard", May 1993.
+
+ [14] Seward, J., "libbz2 and bzip2".
+
+10.2. Informative References
+
+ [15] "libTheora: Available from the Xiph website,
+ http://www.xiph.org".
+
+ [16] "Theora I specification: Codec setup and packet decode.
+ http://www.xiph.org/theora/doc/Theora_I_spec.pdf".
+
+ [17] Friedman, T., Caceres, R., and A. Clark, "RTP Control Protocol
+ Extended Reports (RTCP XR)", RFC 3611, November 2003.
+
+ [18] "ITU-T Recommendation V.42, 1994, Rev. 1. Error-correcting
+ Procedures for DCEs Using Asynchronous-to-Synchronous
+ Conversion. International Telecommunications Union. Available
+ from the ITU website, http://www.itu.int".
+
+ [19] "ISO 3309, October 1984, 3rd Edition. Information Processing
+ Systems--Data Communication High-Level Data Link Control
+ Procedure--Frame Structure. International Organization for
+ Standardization.".
+
+
+
+
+
+
+
+
+
+
+
+
+
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+
+
+Author's Address
+
+ Luca Barbato
+ Xiph.Org
+
+ Email: lu_zero at gentoo.org
+ URI: http://www.xiph.org/
+
+
+
+
+
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+
+Intellectual Property Statement
+
+ The IETF takes no position regarding the validity or scope of any
+ Intellectual Property Rights or other rights that might be claimed to
+ pertain to the implementation or use of the technology described in
+ this document or the extent to which any license under such rights
+ might or might not be available; nor does it represent that it has
+ made any independent effort to identify any such rights. Information
+ on the procedures with respect to rights in RFC documents can be
+ found in BCP 78 and BCP 79.
+
+ Copies of IPR disclosures made to the IETF Secretariat and any
+ assurances of licenses to be made available, or the result of an
+ attempt made to obtain a general license or permission for the use of
+ such proprietary rights by implementers or users of this
+ specification can be obtained from the IETF on-line IPR repository at
+ http://www.ietf.org/ipr.
+
+ The IETF invites any interested party to bring to its attention any
+ copyrights, patents or patent applications, or other proprietary
+ rights that may cover technology that may be required to implement
+ this standard. Please address the information to the IETF at
+ ietf-ipr at ietf.org.
+
+
+Disclaimer of Validity
+
+ This document and the information contained herein are provided on an
+ "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
+ OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
+ ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
+ INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
+ INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
+ WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
+
+
+Copyright Statement
+
+ Copyright (C) The Internet Society (2006). This document is subject
+ to the rights, licenses and restrictions contained in BCP 78, and
+ except as set forth therein, the authors retain all their rights.
+
+
+Acknowledgment
+
+ Funding for the RFC Editor function is currently provided by the
+ Internet Society.
+
+
+
+
+Barbato Expires January 22, 2007 [Page 25]
+
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