I do exactly that (in Obj-C) with AAC files and the AVAudioPCMBuffer’s floatChannelData is indeed raw PCM data.
> On Jul 2, 2018, at 1:36 PM, Waverly Edwards <[email protected]> wrote: > > Would someone provide guidance on how I can decompress M4A and AAC files into > memory as raw LPCM. > I need to decompress M4A and AAC files, manipulate and recompress the files > back to disk. > Writing data from LPCM to M4A or AAC is not a problem (except AAC file > durations are always wrong but will play) > > I can read .caf, .m4a, .aac files into the buffer using the below code but > only the .caf files are actually raw and allow me to work directly with the > buffer contents > > let file = try? AVAudioFile(forReading: url) > let buffer = AVAudioPCMBuffer(pcmFormat: file!.processingFormat, > frameCapacity: AVAudioFrameCount(file!.length)) > do { > try file!.read(into: buffer!) > } catch { > // problem, do something > } > > I looked into AVAudioCompressedBuffer but I do not see how I get the data > into this type of buffer and how to expand this into raw data for manipulation > > If it matters, I am programming on OSX (Sierra). > > Any advice? > > Thank you, > > > W. > _______________________________________________ > Do not post admin requests to the list. They will be ignored. > Coreaudio-api mailing list ([email protected] > <mailto:[email protected]>) > Help/Unsubscribe/Update your Subscription: > https://lists.apple.com/mailman/options/coreaudio-api/matt%408dio.com > <https://lists.apple.com/mailman/options/coreaudio-api/matt%408dio.com> > > This email sent to [email protected] <mailto:[email protected]>
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