[opus] Ogg Format

[Amit Ashara]

Hello Ralph

I ran the opusenc.exe on a wave file and checked the OpusTag section. My
concern is on Total Segment Size being >> than the actual data being put.
Is this just an example of implementation or does a size of 764 BYTES kept
as a place holder for putting more data?

4f 67 67 53 = Oggs
00 = Version
00 = Header
00 00 00 00 00 00 00 00 = Granule Position
a5 73 00 00 = Bit Stream Serial Number
01 00 00 00 = Page Sequence Numner
90 a9 36 42 = Checksum
03 = Page Segments
ff ff fe = Each Segment Size (TOTAL SIZE IS 764 BYTES)
4f 70 75 73 54 61 67 73 = OpusTags
0b 00 00 00 = Vendor String Length of 11
6c 69 62 6f 70 75 73 20 31 2e 31 = "libopus 1.1"
03 00 00 00 = User Comment List Length of 3
25 00 00 00 = User Comment #0 String Length of 37
45 4e 43 4f 44 45 52 3d 6f 70 75 73 65 6e 63 20 66 72 6f 6d 20 6f 70 75 73
2d 74 6f 6f 6c 73 20 30 2e 31 2e 39 = "ENCODER=opusenc from opus-tools
0.1.9"
0a 00 00 00 = User Comment #1 String Length of 10
74 69 74 6c 65 3d 48 4f 4c 41 = "title=HOLA"
1e 00 00 00 = User Comment #2 String Length of 30
45 4e 43 4f 44 45 52 5f 4f 50 54 49 4f 4e 53 3d 2d 2d 6d 61 78 2d 64 65 6c
61 79 20 32 30 = "ENCODER_OPTIONS=--max-delay 20"
00 00 00... ALL THE WAY TO THE NEXT Oggs Container

Regards
Amit

On Tue, May 10, 2016 at 10:47 PM, Ralph Giles <giles at thaumas.net> wrote:

> On 10/05/16 02:37 PM, Amit Ashara wrote:
>
> > Is there a format document on the OpusTag structure? Search always shows
> > up Vorbis but not Opus.
>
> The basic format is shared with Vorbis, but the 'magic signature' is
> different ('OpusTags' instead of '0x05vorbis') and vorbis puts a 0x01
> value in an extra byte after the last tag.
>
> The OpusTag packet layout is described in
> https://tools.ietf.org/html/rfc7845.html#section-5.2
>
> Common tag names used for interoperability are described in the Vorbis
> documentation. See https://www.xiph.org/vorbis/doc/v-comment.html
> There are more extensive tag lists on some other sites.
>
>
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