[theora-dev] Re: Ogg mux design

Ralph Giles giles at xiph.org
Tue Feb 17 13:23:22 PST 2004

On Mon, Feb 16, 2004 at 09:12:01PM -0500, Monty wrote:

> There's a second larger difference; ordering everything by start means
> granule positions are no longer in monotonically increasing order.  I
> have to seek according to start time (to make the bisection work)
> which means I must recalculate start granules for any seek operation.
> The way things are right now, the granpositions as encoded are the
> ones I use directly.

Well, a long discussion with Derf has clarified my thinking a bit. I 
believe one of the differences in our proposals is that you're seeking 
to maintain an absolute temporal order to the packets, while I'm just 
trying to make a 'best effort' and the interleave so the decoder has a 
reasonable time of it. To quote oggstream.html:

The pages of concurrently multiplexed bitstreams need not conform to a 
regular order; the only requirement is that page n of a logical 
bitstream follow page n-1 in the physical bitstream. There are no 
restrictions on intervening pages belonging to other logical bitstreams. 
(Tying page appearance to bitrate demands is one logical strategy, ie, 
the page appears at the chronological point where decode requires more 

>From talking through the implications with derf, your proposal seems to 
be changing this to a requirement for strict ordering.

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