mplayer: changing speed without changing pitch (avoiding the chipmunk effect)
In mplayer, you can change the playback speed with [ or ], but that probably changes the pitch as well (naturally). Can be amusing the first time, but not after you realise that it is actually possible to do something sophisticated to avoid this. (Wikipedia calls it Audio timescale-pitch modification) Many other media players (including VLC and even Windows Media Player(?)) can do this automatically; here’s how to do it in mplayer.
Start mplayer as mplayer -af scaletempo
That’s it. The catch is that you need to get an mplayer which has the scaletempo filter, and we know how much the mplayer project loves making releases. (It’s not in Ubuntu at the time of writing.)
Start mplayer as mplayer -speed 1.5 -af ladspa=tap_pitch:tap_pitch:0:-33:-90:0 foo.avi
Seems even the latter might require installing the ladspa plugins.
For more on all this, see: