[vorbis] My Vorbis beta 2 impressions

Monty xiphmont at xiph.org
Tue Aug 22 00:44:18 PDT 2000

> > Also, even though the ogg files are EXACTLY the same length as the original
> > wav files, I can still hear a tiny <click> between songs that flow into one
> > another. This doesn't happen always, some files come out fine, some have
> > (more or less audible) clicks between them.
> When going from track to track, the transition is not 'lapped'.  frames in 
> Vorbis (like in mp3) are actually overlapping transforms, but between two 
> songs, obviously there is no overlap and because the compression is lossy (nad 
> the us the output an approximation) where there is no smooth overlap, the end 
> and beginning may not match up exactly.
> One could actually set up the encoder to pay more attention to this to make 
> sure that the approximation *does* match up on the other side...

Actually, I just realized I may be doing something silly in the encoder that's 
seriously exacerbating the problem... IIRC, I'm padding end of song/end of 
frame with zeroes so that we have enough data for the last frame; Vorbis knows 
not to include these zeros at the end, but it does add a potentially large 
high frequency spike in the last frame which will spread and make the 
approximation much harder.  Eliminating that problem is both The Right Thing 
To Do and reasonably easy.


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