Not sure why this is so hard...doubling audio speed

Discussion in 'Digital Audio' started by akm3, Sep 12, 2011.

  1. akm3 macrumors 68020

    Nov 15, 2007
    I have a file I recorded from a 4-track tape deck that recorded the audio at double tape speed i.e. it plays back at half speed.

    I want to take that MP3 file and make it twice as fast. This seemingly trivial thing seems impossible to accomplish. I open it in soundtrack pro (I don't have much experience with it) and the clip speed options are grayed out. There are options to change the pitch without changing the speed, and change the speed without changing the pitch, but this all seems too complicated. How do I just make it go twice as fast?
  2. TMRaven macrumors 68020


    Nov 5, 2009
    Download Audacity.
    Open up Audacity.
    Drag MP3 into Audacity.
    Select Effect > Change Temp.
    Under Length (seconds) halve the time on the 'to' box.
  3. Jolly Jimmy macrumors 65816

    Jolly Jimmy

    Dec 13, 2007
    The effect you need to select in Audacity is change speed, not change tempo. It modifies both the tempo and the pitch proportionally as you would need with a tape that plays back at the wrong speed.
  4. TMRaven macrumors 68020


    Nov 5, 2009
    Yes if you want to just make it twice as fast in audacity, use change tempo. If you want to change both speed and pitch, use change speed.
  5. akm3 thread starter macrumors 68020

    Nov 15, 2007
    Thank you guys this worked great.

    Although I'm now finding I got a TON of noise off the tape, I think my only choice is to locate a (hopefully cheap) Marantz PMD-740 4 track tape deck with the speed increase feature and see if I can't get cleaner audio off this...15 year old (yikes!) tape!

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