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Re: Getting PCM data from MP3/AAC/ALAC File
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Re: Getting PCM data from MP3/AAC/ALAC File

  • Subject: Re: Getting PCM data from MP3/AAC/ALAC File
  • From: William Bates <email@hidden>
  • Date: Sat, 20 Dec 2008 09:08:59 -0600
For better or worse, the designers of Core Audio picked floats as the "natural" representation. I personally think it was the best choice, although some will quibble about the number of bits of resolution and would argue for doubles.
In Core Audio, if you want something other than the canonical stream format (stereo, 44.1, float) you generally obtain it as the output of an AudioConverter. Apple doc is vague about exactly when you need to use AudioConverters, since it depends on what you're doing with the stream.
AudioConverters can be a pain to implement. Fortunately some of the higher-level APIs create reliable AudioConverters for you. ExtAudioFile creates a single AudioConverter for you which, in the input/read case, converts from file format (e.g., mp3) to canonical. AudioQueue also creates one. It's often helpful to ask "where is the converter?" is using these APIs.
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    • Re: Getting PCM data from MP3/AAC/ALAC File
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References: 
 >Getting PCM data from MP3/AAC/ALAC File (From: Daniel Staudigel <email@hidden>)
 >Re: Getting PCM data from MP3/AAC/ALAC File (From: Daniel Staudigel <email@hidden>)
 >Re: Getting PCM data from MP3/AAC/ALAC File (From: Daniel Staudigel <email@hidden>)
 >Re: Getting PCM data from MP3/AAC/ALAC File (From: William Bates <email@hidden>)
 >Re: Getting PCM data from MP3/AAC/ALAC File (From: William Bates <email@hidden>)
 >Re: Getting PCM data from MP3/AAC/ALAC File (From: Daniel Staudigel <email@hidden>)

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