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

From: [email-masked]
Date: Wed, 05 Mar 2003 16:26:33 +1100

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
> 

_______________________________________________
Audio/Video Transport Working Group
[email-masked]
https://www1.ietf.org/mailman/listinfo/avt

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From: Harald Tveit Alvestrand <[email-masked]>
Date: Wed, 05 Mar 2003 07:10:34 +0100

Thank you, and thanks for taking the time to understand my worry and 
addressing it!

Based on the info below, I should have no problems letting this progress!

--On onsdag, mars 05, 2003 16:26:33 +1100 [email-masked] wrote:

> 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
> and may be put in front of the IESG again to be moved to an informational
> RFC.