[ogg-dev] Header packet multiplicity

ogg.k.ogg.k at googlemail.com ogg.k.ogg.k at googlemail.com
Wed Feb 13 10:19:07 PST 2008

> There are a usually lot more data packets than header packets, so
> having an internal length there hurts your bitrate a lot more. Of
> course, it may not be significant for an uncompressed text codec.

If muxed with a video, it's insignificant (well, for my test cases).

> With codecs using the 'count of decodable samples' rule to calculate
> their granulepos, the headers can often be distinguished by having a
> granulepos that maps to time zero. I know that works with theora
> (after the change in beta1).

But this for when they're encapsulated in ogg, isn't it ? All is fine when
that is the case, since Ogg provides the framing already so there's no
need to walk the packets.

> Conrad, does this work for the other codecs as well? I vaguely
> remember libvorbis putting -1 on the header packets instead of 0.

AFAIK, it's 0, -1 being for partial pages, from the ogg docs. -1 (or, I
suppose all negative values, but I'm not sure) mean unset.

Though you do say packets rather than pages, and the granulepos for
a vorbis packet will be interpolated from the page's granulepos, so I
assume you meant page ?

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