ogg dev - Jun 2008 - How Ogg mappings translate into the codecs parameter in Ogg media types

"Silvia Pfeiffer" <silviapfeiffer1 at gmail.com> wrote:
...
> Also, it would be good if we can keep
> our magic numbers to the first 8 bytes.
So Kate and Yuv4mpeg both need to be trimmed.
...
>>>  char[9]: '\x80kate\0\0\0\0'  | kate
>>>  char[9]: 'YUV4MPEG2'         | yuv4mpeg
Regards,
Martin
-- 
Martin J Leese
E-mail: martin.leese stanfordalumni.org
Web: http://members.tripod.com/martin_leese/

>> Also, it would be good if we can keep
>> our magic numbers to the first 8 bytes.
>
> So Kate and Yuv4mpeg both need to be trimmed.
> ...
>>>>  char[9]: '\x80kate\0\0\0\0'  | kate
After thinking about it, if deemed to be helpful, I can switch
the signature to "\x80kate\0\0\0" and mandate a reserved
0 byte field following it. The actual bitstream format would
not change, only the interpretation of the magic.

I'd then do a similar hack in other headers, which also have
the magic (with a different packet type byte).

I think it would be helpful. Being able to say that the magic resides
in the first 8 bytes for all our codecs is a plus when it comes to
parsing and consistency. We could go for 9 instead, but that's
somewhat of an odd number...

I don't think the \x80 is too much of an issue, but I don't know what
that packet type field is really used for.

Cheers,
Silvia.

On Fri, Jun 13, 2008 at 1:51 AM, ogg.k.ogg.k at googlemail.com
<ogg.k.ogg.k at googlemail.com> wrote:
>
>>> Also, it would be good if we can keep
>>> our magic numbers to the first 8 bytes.
>>
>> So Kate and Yuv4mpeg both need to be trimmed.
>> ...
>>>>>  char[9]: '\x80kate\0\0\0\0'  | kate
>
> After thinking about it, if deemed to be helpful, I can switch
> the signature to "\x80kate\0\0\0" and mandate a reserved
> 0 byte field following it. The actual bitstream format would
> not change, only the interpretation of the magic.
>
> I'd then do a similar hack in other headers, which also have
> the magic (with a different packet type byte).
>
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