[SoX-users] tempo effect leaves unexpected near-zero amplitude data at end of segment

[forget c. <for...@gm...>]

Hi,

I've been working with the tempo effect and have found something
unexpected. When I use tempo on a segment of a file, such as:

> sox in.wav out.wav trim 0 1 tempo -m 1.1

I get a file with the appropriate adjustment (faster, same pitch), but the
end of the file (the last .006 seconds in this case) is silence (or near
it---I haven't spit out the sample values to see if they're truly 0 or not).

This behavior appears to hold true regardless of the direction of tempo
change, so:

> sox in.wav out.wav trim 0 1 tempo -m 0.9

Also leaves silence at the end of the file (in this case, about .025 worth).

This behavior isn't a problem for single segments, but I'm trying to make
sequential adjustments to a file, such as:

> sox in.wav out.wav trim 0 1 tempo -m 0.9 : trim 0 1 tempo -m 1.1 : ...

And so the silence at the end of every segment is causing issues.

Is there a way around this, and/or is this intended/expected behavior? If I
could predict how much silence it will append/insert, I could trim it off
with silence, but I don't see how to predict it.

Thanks,
fg