[vorbis-dev] application/ogg is a proposed Internet standard.

[Harald Tveit Alvestrand]

(note - this thread is being forked with different CCs on the different 
threads....is that good or bad?)

If I were doing this, and wanted things done in a hurry, I'd add a sentence 
something like this:

"OGG players identify the codec being used for a stream by looking at the 
first packet. Normally, some initial number of bytes has a well known fixed 
value (such as 0x00 'vorbis' for the Vorbis codec), and it's the 
responsibility of anyone fielding a new codec to make sure it's 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."

One could add some words about some location (xiph.org) serving as a place 
to share information, or the possibility that registration functions will 
be created some time in the future...  but I think getting the registration 
functions done right (whatever "right" is) will take some time, and it 
would be nice to get this doc out the door Real Soon Now....

but that's my take. tastes may differ.

                         Harald

--On 28. januar 2003 16:49 +0000 Ralph Giles <giles at xiph.org> wrote:

>>   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?)
>
> Well, this was intentionally vague beyond the idea that identification
> should be possible from the first packet. For vorbis it's the first 7
> bytes of any of the first three packets, but given the open-ended nature
> of the encapsulation intention, it's not possible to be more specific
> than that. I.e. we don't have reserved 4-character codec labels or such.
>
> Perhaps it's worth adding a sentence along the lines of: "Such an
> encoding (encapsulation?) specification SHOULD endeavor to make codec
> identification possible through matching some number of initial bytes."
> All current ogg-encapsulated forms work this way afaik.

<p>--- >8 ----
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