[vorbis-dev] Idea for gapless tracks

[Marshall Eubanks]

Aleksandar Dovnikovic wrote:
> 
> We all know that currently Vorbis is the only codec out there that
> doesn't add any silence to the decoded file, so when you decode
> your .ogg file the resulting .wav will be exactly the same length
> as the original one. This is very useful when encoding gapless
> songs (like live concerts...). But since Vorbis is a lossy codec,
> even though there is no silence added, sometimes you can
> still hear a click between gapless tracks because the end of
> the first song doesn't match up with the beginning of the second
> song. This doesn't happen always and as you encode files using
> higher bitrates these clicks seem to appear less frequently
> (as expected).
> 
> One of the solution would be to "teach" the encoder that
> it has to pay attention that the end of one songs should
> match up with the beginning of another one. But I'm
> thinking that there might be a better solution: the encoder
> shouldn't use psycho-acoustic at the very begging &
> very end of the songs (for a few milli seconds). This will
> ensure that the edges will always match...
> 
> Does this holds water or not?
> 
> Greetings,
> Aleksandar
> 

I would do this on playback if possible.

If the levels don't line up at the join, then you'll hear a click or a pop.
You can smooth the area around the join (say, +- 10 samples, applying a
10 sample moving
average) to try and
remove this. This can also happen if you do things like change bit rates
in the
middle of a piece.

-- 

                                   Regards
                                   Marshall Eubanks

   Multicast Technologies, Inc.
   10301 Democracy Lane, Suite 201
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