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MP3 hardware-assisted decoding on ipad
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MP3 hardware-assisted decoding on ipad


  • Subject: MP3 hardware-assisted decoding on ipad
  • From: "Juan P.Pertierra" <email@hidden>
  • Date: Mon, 10 May 2010 09:28:27 -0400

Hello,

I am trying to decode an MP3 into PCM directly into memory using the MP3 decoder hardware in the iPad.  I have started with the iPhoneExtAudioFileConvert example, which sets the client data format to 16-bit PCM and uses ExtAudioFileRead to read and do the conversion on the fly(if i understand correctly).

This works but even after allocating all the memory for the PCM file, it takes about 20 seconds to convert a 6minute MP3 file.

Is this the best MP3 decoding performance? Or is there a faster method?  I noticed that getting the kAudioConverterPropertyCanResumeFromInterruption returns an error -50, I think this means hardware decoding is not available, so perhaps there is another way?

I need to decode the entire thing, so I can't work in blocks for this part of the app.

I also tried the audioqueue offline render services example but that takes even longer, at least twice as long.

Thanks,
Juan


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