Hi!
Ecasound can do a lot of wat you need. Sox may be nice for a few things. For
resampling I'd stick to the sndfile-resample tool.
For the more elobarte things csound might do the trick. You can also script
it.
For stretching and pitch-shifting there's also soundtouch/soundstretch.
HTH.
Kindest regards
Julien
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