[vorbis-dev] audio/vorbis media type registration

[Linus Walleij]

This is the first draft of the audio/vorbis media registration form to be
handled to the IANA. PLEASE comment extensively, even minor spelling
mistakes etc are to be stamped out of this I hope.

A media type for application/ogg (or should it be
application/oggsquish?) will be created separately.

I would be very happy if someone could supply the 4-letter filetype code
used by MacIntosh .ogg files.

Linus Walleij

--------
MIME media type name:   audio

MIME subtype name:      vorbis

Required parameters:    none

Optional parameters:    none

Encoding Considerations:

        The vorbis audio data is usually wrapped inside an OggSQUISH
        bitstream, see [OGG].

        The vorbis audio data is binary data, and must be encoded for
        non-binary transport; the Base64 encoding is suitable for Email,
        Binary encoding could also be used. Further lossless compression
        may be problematic as the vorbis data is already efficiently 
        compressed using psychoacoustic algorithms with highly optimized
        bit-allocation.

Security Considerations:

        Ideally, the vorbis file can not contain security-violating code
        as the format is highly specified, see [VORBIS] and/or [COLEMAN].
        However, fields can be abused if the recieving decoder
        implementation has errors or extensions that make it possible
        to embed interpretative or object code. The recieveing decoder
        must therefore take these issues into account, and under no
        circumstances allow untrusted code to be executed.

        Vorbis files are not signed or encrypted using any applicable
        encryption schemes. External security mechanisms must be added
        if content confidentiality and autencity is to be achieved.

Interoperability considerations:

        The vorbis format has proved to be widely implementable across
        different computing platforms. An example implementation exists
        that has been compiled on numerous platforms.

        The technology involved in vorbis encoding and decoding is not
        patented and may be used by third parties without patent
        licenses or similar licensing issues.

Published specification:

        See [VORBIS] and/or [COLEMAN].

Applications which use this media type:

        Any application that implements the specification will be able
        to encode or decode vorbis files.

Additional information:

        Magic number(s): For vorbis files wrapped inside OggSQUISH
                         files, the first four bytes are 0x4f 0x67
                         0x67 0x53 corresponding to the string "OggS".
                         The vorbis header will then additionally
                         contain the lowercase string "vorbis"
                         (comprising the bytes 0x76 0x6f 0x72 0x62
                         0x69 0x73) at offset 0x1d, where offset 0x00
                         is the first byte of the file.

                         If vorbis files were to be delivered without
                         the OggSQUISH header the "vorbis" string would
                         appear at offset 0x01. This should never occur.

        File extension:  .ogg

        Macintosh File Type Code(s):    none

        Object Identifier(s) or OID(s): none

Person & email address to contact for further information:

        Questions about this proposal should be directed to Linus
        Walleij <triad at df.lth.se>. Technical questions about the
        ogg and vorbis standards may be asked on the mailing lists
        for respective developer community, see
        <http://www.xiph.org/archives/>

Intended usage:         COMMON

Author/Change controller:

        This document was written by Linus Walleij <triad at df.lth.se>,
        changes of this document will be handled by him or a
        representative of the Xiphophorus company or the Vorbis
        development community.

        The Vorbis format, and its superformat OggSQUISH are controlled
        by the Xiphophorus company and the respective development
        communities.

References:

 [OGG]
     Xiphophorus company, "OggSquish logical and physical bitstream
     overview".
     <url:http://xiph.org/ogg/vorbis/doc/oggstream.html>

 [VORBIS]
     Xiphophorus company, "Ogg Vorbis Audio Bitstream".
     <url:http://xiph.org/ogg/vorbis/doc/vorbis-stream.html>

 [COLEMAN]
     Coleman, Mike, "Vorbis Illuminated".
     <url:http://www.mathdogs.com/vorbis-illuminated/>

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