How can I get / extract raw (no sound) audio data from the caf file on the iPhone?

Question

I am working on a project that requires me to send raw data to the server without header or linear pcm data.

I use AVAudioRecorder, and I can easily save audio files on the phone, but the problem is that no matter what I do and do, they are wrapped in a caf file or marked with some kind of header.

I understand that the caf file is just a wrapper file for raw audio data and that this audio data can be in various formats, including linear pcm and ulaw.

So my questions are: how can I generate a raw sound file without a caf shell to start with it (i.e. just alkaline raw sound added to the file), or if I record a caf that contains raw Ulaw sound or linear pcm audio data, how can I easily enter and extract only raw audio data from the caf file and leave everything else.

Answer 1

If you use the Audio Queue API for recording, instead of AVAudioRecorder, you will have access to the sample buffers of the original PCM buffer and you can write them to a flat file for later sending to your server.

Answer 2

CAF , , API AudioFile caf /RAW .

CAF, API ExtAudioFile. , .

http://developer.apple.com/library/ios/#documentation/MusicAudio/Reference/AudioFileConvertRef/Reference/reference.html

http://developer.apple.com/library/ios/#documentation/MusicAudio/Reference/ExtendedAudioFileServicesReference/Reference/reference.html