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[AVT] Re: New I-Ds for Ogg technologies (Vorbis over RTP, Ogg file format,Mimetypes)

Dear Allison, all,

thank you very much for getting the application/ogg MIME type on its way. The accompanying I-D still needed some work and after extensive discussions in the Xiph/Ogg community, we have now submitted an updated version. It should become available soon at http://www.ietf.org/internet-drafts/draft-pfeiffer-ogg-fileformat-02.txt
and may be put in front of the IESG again to be moved to an informational RFC.

Best Regards,

Silvia Pfeiffer.

Here's the list of major changes:

1) The paragraph of trouble changed to (Section 4):

Each Ogg page contains only one type of data as it belongs to one logical bitstream only. Pages are of variable size and have a page header containing encapsulation and error recovery information. Each logical bitstream in a physical Ogg bitstream starts with a special start page (bos=beginning of stream) and ends with a special page (eos=end of stream). The bos page contains information to uniquely identify the codec type and MAY contain information to set up the decoding process. The bos page SHOULD also contain information about the encoded media - for example, for audio, it should contain sample rate and number of channels. By convention, the first bytes of the bos page contain magic data that uniquely identify the required codec. It is the responsibility of anyone fielding a new codec to make sure it is possible to reliably distinguish his/her codec from all other codecs in use. There is no fixed way to detect the end of the codec-identifying marker. The format of the bos page is dependent on the codec and therefore MUST be given in the encapsulation specification of that logical bitstream type. An example for such a media mapping is "Ogg Vorbis", which provides the name and revision of the Vorbis codec, the audio rate and the audio quality on the Ogg Vorbis bos page. The vorbis bos page starts with the byte 0x01, followed by "vorbis" (a total of 7 bytes of identifier).


2) Another major change was made to the paragraph on "Theora", the video codec (Section 4):

Another example is the upcoming "Ogg Theora" specification which encapsulates Theora-encoded video data and usually comes multiplexed with a Vorbis stream for an Ogg containing synchronised audio and video. As Ogg does not specify temporal relationships between the encapsulated concurrently multiplexed bitstreams, the temporal synchronisation between the audio and video stream will be specified in this media mapping.

3) All the other changes were minor editorial ones.



Allison Mankin wrote:
Silvia, AVT WG, Chairs,

We IESG passed draft-walleij-ogg-mediatype-08.txt as a Proposed
Standard today.  It had had a four week Last Call some time back and
was not changed, other than now having the internet-draft available to
document the fileformat.  Congratulations!

The accompanying i-d, draft-pfeiffer-ogg-fileformat, was on the agenda
as well and Harald Alvestrand raised a technical question that needs
to be resolved before we can progress it as Informational.  Harald's
written question:

  Technical omission (I think): The document says that the BOS page
  "contains information to identify the codec type and any additional
  information to set up the decoding process.  The format of that page
  is therefore dependent on the codec and therefore MUST be given in
  the encoding specification of that logical bitstream type."

  It's pretty clear that OGG players can identify which codec is being
  used. But this document does not say which bytes of the BOS page can
  be used to identify the codec. (first 4 bytes? first 16 bytes? up to
  the first NUL?)

Thanks,

Allison


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