[vorbis-dev] ogg_sync_state with discontinuous codecs

[Arc]

On Wed, Dec 03, 2003 at 10:06:18AM -0800, Aaron Colwell wrote:
> It also doesn't easily handle sparse or discontinuous media like Arc 
> says. I'm just interested in why this design decision was made.

I'd like to point out that discontinuous refers to "overlapping".  I 
believe that sparse (ie, a MNG video frame every minute) codecs can use 
the same rules as continuous bitstreams.  This condition of needing to 
change the rules (if nothing more than the coders' sanities) only needs 
to apply to bitstreams where packets overlap in the time they cover.

I guess another way of saying it would be to call it "non-sequential" or 
"non-serial".  Whereas the granules covered by audio and video packets 
are end to end, that is, you can expect the first granule of the next 
page to be the granulepos of the last + 1.  When they overlap we have a 
problem with, well, having to make all sort of extra things as far as 
muxing goes.. for instance, the codec would actually have to be process 
it's bitstreams to tell a muxer the start location, since without this 
change, the granulepos would be the last granule for which it's valid 
(it's expiration time), and what do you do when the next page starts 
the one which expires before it (and thus has a lower granulepos)? 

<p>--- >8 ----
List archives:  http://www.xiph.org/archives/
Ogg project homepage: http://www.xiph.org/ogg/
To unsubscribe from this list, send a message to 'vorbis-dev-request at xiph.org'
containing only the word 'unsubscribe' in the body.  No subject is needed.
Unsubscribe messages sent to the list will be ignored/filtered.