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I'm looking for a Windows command-line tool that will allow me to increase the playback speed of MP3 files (podcasts and audiobooks). Preferrably free or open source.

Update: I want to be able to listen to a 1 hour podcast in less than 60 minutes, but it would be nice if the pitch wasn't changed.

If necessary, I can convert the MP3 to WAV first and then back again.

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Increase the speed like make them sound chipmunky and have the file shorter? – MrStatic Jan 2 '10 at 8:46
ideally this would be a function built into the player, so you wouldn't have to process audio first, then play it. sadly not all players (software or hardware) include add-on/plugin capabilities. – quack quixote Jan 2 '10 at 9:06
Yes, my MP3 player does support faster playback, but it doesn't always work, and I'd like to fine-tune the speed setting. – Christian Davén Jan 2 '10 at 9:12
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this free web service may be of interest to you: podshifter.com – Molly7244 Jan 2 '10 at 16:32
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2 Answers

up vote 4 down vote accepted

SoX, the Swiss Army knife of sound processing programs, can do this without a hitch:

sox --show-progress input.mp3 output.mp3 speed 1.5 pitch -700

specifying a lower pitch will prevent your files from getting the "chipmunk" effect. 700 may not be exact for your file, so you can play around with pitch until it sounds right.

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Thanks, but it removes all ID3 data after re-encoding. – Christian Davén Jan 2 '10 at 9:35
SoX doesn't have support for MP3 by default, but there's a build at CodeProject with Lame and Mad built-in: codeproject.com/KB/aspnet/Compiling_SOX_with_Lame.aspx (or follow the build instructions in README.win32.txt) – Christian Davén Jan 2 '10 at 16:38
Awesome, nice find! – John T Jan 2 '10 at 16:43
Use the switch "tempo" instead of "speed" and the pitch won't be changed. I ended up converting my MP3s to WAV, running SoX, encoding back to MP3 and re-insert ID3 tags... – Christian Davén Jan 2 '10 at 23:12
@Christian: SoX does the conversion from-and-to WAV itself; that's an extra step you can do without (it processes the uncompressed audio data, not the MP3 stream). if you don't overwrite your original files, you should be able to get an MP3 tagger to copy the tags from the original files to the new ones (if nothing else works, this should be easily scriptable in Python using the Mutagen tagging library). – quack quixote Jan 3 '10 at 18:37
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up vote 1 down vote

the best: mp3-speed.en.softonic.com/

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