[annodex-dev] RE: ogg skeleton/ basegranule (was Re: zen's comments on new anx spec)

Conrad Parker conrad at metadecks.org
Sun Jan 30 12:53:23 EST 2005


On Sun, Jan 30, 2005 at 12:40:22PM +1100, Silvia.Pfeiffer at csiro.au wrote:
> Specifying a hole at the beginning of a vorbis track in Ogg is not really catered for IMHO. Maybe you can create a page without any content that declares at what time (or rather: granulepos) it ends (and thus the data starts). Not sure what decoders would do with pages without content (i.e. silence) though.

sure it is: the original file has the first theora frames starting from
time zero, and the first vorbis frames starting some time later. So,
there'll be many theora packets before the first vorbis packet. You
infer the timestamps from the granulepos. No extra pages required.

detecting holes (by comparing granulepos's to the pcm samples available)
is a required for decoding ogg vorbis correctly.

Conrad.



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