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iosswiftavfoundationnsdataavaudiopcmbuffer

Converting AVAudioPCMBuffer to NSData

I'm currently trying to convert the audio samples from AVAudioPCMBuffer to NSData - I had taken a look at the accepted answer on this SO Post and this code from GitHub but it appears some of the AVFAudio API's have changed...below is the extension I have for AVAudioPCMBuffer:

private extension AVAudioPCMBuffer {

    func toNSData() -> NSData {
        let channels = UnsafeBufferPointer(start: int16ChannelData, count: 1)
        let ch0Data = NSData(bytes: channels[0], length:Int(frameCapacity * format.streamDescription.inTotalBitsPerChannel))

        return ch0Data
    }

}

I'm seeing an error of Value of type 'UnsafePointer<AudioStreamBasicDescription>' has no member 'inTotalBitsPerChannel'. So far, I've not been able to find out any other way to find out the inTotalBitsPerChannel value...any help appreciated!

Solution

  • I don't see any method named inTotalBitsPerChannel in either of the code samples you linked to; instead, they both seem to use mBytesPerFrame. You will also need .pointee to dereference the pointer. Finally, in modern Swift, you should generally prefer to use Data over NSData. So, basically, I think your extension should work if you rewrite the last line to:

    let ch0Data = Data(bytes: channels[0], count: Int(frameCapacity * format.streamDescription.pointee.mBytesPerFrame))