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

[Silvia.Pfeiffer at csiro.au]

Well, the Ogg pages specify the end time of the data in the granulepos - so if your data does not cover the complete time, where are you supposed to leave your hole? At the beginning? Then I agree, that would make it work. But is that really what players do?

Silvia.


-----Original Message-----
From:	Conrad Parker on behalf of Conrad Parker
Sent:	Sun 1/30/2005 12:53 PM
To:	Pfeiffer, Silvia (ICT Centre, Marsfield)
Cc:	annodex-dev at lists.annodex.net
Subject:	Re: [annodex-dev] RE: ogg skeleton/ basegranule (was Re: zen's comments on new anx spec)

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.