How do I call CMSampleBufferGetAudioBufferListWithRetainedBlockBuffer?

Question

I\'m trying to figure out how to call this AVFoundation function in Swift. I\'ve spent a ton of time fiddling with declarations and syntax, and got this far.

Answer 1

Martin's answer works and does exactly what I asked in the question, however, after posting the question and spending more time with the problem (and before seeing Martin's answer), I came up with this:

public func captureOutput(
    captureOutput: AVCaptureOutput!,
    didOutputSampleBuffer sampleBuffer: CMSampleBuffer!,
    fromConnection connection: AVCaptureConnection!
) {
    let samplesInBuffer = CMSampleBufferGetNumSamples(sampleBuffer)
    self.currentZ = Double(samplesInBuffer)

    let buffer: CMBlockBufferRef = CMSampleBufferGetDataBuffer(sampleBuffer)

    var lengthAtOffset: size_t = 0
    var totalLength: size_t = 0
    var data: UnsafeMutablePointer = nil

    if( CMBlockBufferGetDataPointer( buffer, 0, &lengthAtOffset, &totalLength, &data ) != noErr ) {
        println("some sort of error happened")
    } else {
        for i in stride(from: 0, to: totalLength, by: 2) {
            // do stuff
        }
    }
}

This is a slightly different approach, and probably still has room for improvement, but the main point here is that at least on an iPad Mini (and probably other devices), each time this method is called, we get 1,024 samples. But those samples come in an array of 2,048 Int8 values. Every other one is the left/right byte that needs to be combined into to make an Int16 to turn the 2,048 half-samples into 1,024 whole samples.