AW: [vorbis-dev] Chained streams and granule position

[Silvia.Pfeiffer at csiro.au]

Hi Alejandro,

"Alejandro G. Belluscio" wrote:
> 
> Hello Tor-Einar,
> 
> Tuesday, November 12, 2002, 7:38:51 PM, you wrote:
> >> The intent of the design is that chained streams should be played
> >> separately and in order. Streams to be played simultaneously (or
> >> concurrently) should be multiplexed.
> 
> TEJ> What about three logical streams interleaved like this, where all
> TEJ> streams start with a granule position of 0:
> 
> TEJ> ABABABACACAC
> This bitstream is illegal. it should be ABCABABACACACB. Note that you
> can't have a start page after a non start page unless it's a finish
> page. And you have to have all the finish pages together. No start
> pages before nor any page after. In other words.
> S(x) means starting page, D(x) means no start nor finish, F(x) means
> finish page.
> Correct Ogg:
> S(a)S(b)S(c)D(a)D(a)D(b)D(c)D(b)D(c)D(a)D(b)D(c)D(c)D(a)F(b)F(c)F(a)
> Incorrect:
> S(a)S(b)S(c)D(a)D(a)D(b)D(c)D(b)D(c)D(a)D(b)D(c)D(c)F(b)D(a)F(c)F(a)
>                                                         ~~~

After what I've been reading in the documentation, ending one logical
bitstream earlier than the others in the same group is allowed. So, this
one should be correct.

I cite from http://www.xiph.org/ogg/vorbis/doc/oggstream.html about
concurrent multiplexing:
"Unlike initial pages, terminal pages for the logical bitstreams need
not all occur contiguously (although a specific media mapping may
require this; it is not mandated by the generic Ogg stream spec)."

Silvia.
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