[vorbis] My Vorbis beta 2 impressions

Monty xiphmont at xiph.org
Tue Aug 22 00:24:25 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...

>  Someone from this list said a
> while ago that when you cut the signal abruptly, clicks can happen
> (something about zero-crossing) and Monty said that this can be easily fixed
> in decoder, so I'm guessing that this click comes from the decoder side??

That's more an issue of a sample ending and then dropping off a digital cliff 
to zero making a high frequency click.  One can smooth that...


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