[vorbis-dev] Bride of vorbisfile questions

[John Morton]

On Thursday 18 December 2003 11:54, Joshua Haberman wrote:
>  On Tue, 2003-12-16 at 00:20, John Morton wrote:
>
>  There are two main reasons why I can't collapse all the data into a
>  single logical bitstream:
>
>  1. the physical bitstream may consist of data that came from several
>  different bitstreams, all with different codebooks.

Can't the codebooks be collected into one header? 

>  > I don't think relying on a physical bitstream being considered a single
>  > entity by player software is a good plan in the long run.
>
>  The spec doesn't really speak to the semantics of what it means to have
>  chained bitstreams within a physical bitstream.  It's not clear to me
>  that either interpretation has more validity based on the spec.

Treating a collection of logical streams as separate tracks makes captured 
streams much more useful, and paves the way for distributing albums as one 
big bitorrent and iceshare friendly physical stream, so it's pretty useful to 
do things this way.

>  For what it's worth, Monty's reply to the message referenced above cited
>  the "chaining" ability as a solution to the lossless editing problem,
>  which would appear to support my interpretation.

I'm not really convinced that general lossless editing is all that useful. I 
can only imagine a few scenarios where I'd be interested in cutting up a 
vorbis streams:

 - spliting a single, continuous live stream into separate tracks.
 
 - spliting my copy of Macbeth by Laibach into the separately named sections  
 mentioned on the back of the album. 
 
  - spliting off the bonus tracks that tend to be tacked on to the end of the
  last track on an album after some period of silence, and losing the silence
  in the process. 

Frankly, all of those splits could be done against the pcm stream with enough 
presence of mind. 

I can really imagine any scenario where I'd want to chop an existing vorbis 
file up into little pieces and reassemble it, let alone add bits from other 
vorbis streams, without wanting to do crosslaping or a dozen other DSP 
effects. It seems to me you'd always be better off going back to the source 
material or decoding to PCM and just dealing with the minimal quality loss of 
a later encode.

What did you have in mind?

John

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