(Ted Harding) wrote:
Interesting! When I look at 'man sox', the word "tempo" does not occur, and the option to slow down/speed up without changing pitch is "stretch". This is sox version 12.17.7 ('sox -h') on a Debian Etch installed late 2007, and the man-page has the date "December 11, 2001" at the end.
$ sox --version sox: SoX v14.2.0
That's on Ubuntu 9.04. I assume it is derived from the latest Debian version, though.
Have things changed recently?
Well there's quite a big version jump, but I don't know the history.
Man page for stretch now says: stretch factor [window fade shift fading] Change the audio duration (but not its pitch). This effect is broadly equivalent to the tempo effect with (factor inverted and) search set to zero, so in general, its results are comparatively poor; it is retained as it can sometimes out-perform tempo for small factors.
[...]
See also the tempo effect.