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I am using the AVAudioRecorder class available with the 3.0 SDK to record audio in my app. I am successfully able to record to a caf/aiff file. But I would like to record to an mp3.

I tried changing some values in the settings dictionary but all I get is a blank file.

  1. Is it possible to record to an mp3 using AVAudioRecorder

  2. If not, how can I transfer the caf files from my app to a computer?

Thanks.

lostInTransit
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3 Answers3

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See:

http://developer.apple.com/iphone/library/qa/qa2008/qa1615.html

IMA is a 4:1 format, which means it will compress to 25% of the original size. It's good enough for voice, but not ideal for music.

Lossless is great for music, but usually only gets 50%.

µLaw and aLaw are older formats that compress to 50%, but are much worse than Lossless.

I haven't used iLBC.

I'd bet you'll never see an MP3 encoder made available to third-party apps due to licensing issues.

lucius
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From all I can find on the API documentation, you can't change the encoder. The only encoder settings I could find that you can change are:

AVEncoderAudioQualityKey;
AVEncoderBitRateKey;
AVEncoderBitDepthHintKey;

As for transferring the file, a typical approach would be to email the file.

Erich Mirabal
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You'll have to include your own MP3 encoder. And you might not be able to do the encoding in real-time. Sad, but there it is.

Mark Bessey
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  • what about m4a? The new voice memo app included with the 3.0 saves the memos in m4a format. So will the AVAudioRecorder also allow saving .m4a files? Thanks – lostInTransit Jun 27 '09 at 07:14
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    http://developer.apple.com/iphone/library/qa/qa2008/qa1615.html This Q&A talks about recording a compressed CAF file, but doesn't mention m4a as a possibility. If you're recording voice data, one of the listed voice-quality encoders will save a lot of space over uncompressed audio. For high-quality recordings, Apple Lossless will be roughly 50% of the size of uncompressed data. – Mark Bessey Jul 02 '09 at 20:36