I'm trying to convert a CMSampleBuffer to a AVAudioPCMBuffer instance to be able to perform audio processing in realtime. I wrote an optional initialiser for my extension to pass a CMSampleBuffer reference. Unfortunately I simply don't know how to write to the AVAudioPCMBuffer's data. Here is my code so far:import AVKit
extension AVAudioPCMBuffer {
static func create(from sampleBuffer: CMSampleBuffer) -> AVAudioPCMBuffer? {
guard let description: CMFormatDescription = CMSampleBufferGetFormatDescription(sampleBuffer),
let sampleRate: Float64 = description.audioStreamBasicDescription?.mSampleRate,
let numberOfChannels: Int = description.audioChannelLayout?.numberOfChannels
else { return nil }
guard let blockBuffer: CMBlockBuffer = CMSampleBufferGetDataBuffer(sampleBuffer) else {
return nil
}
let length: Int = CMBlockBufferGetDataLength(blockBuffer)
let audioFormat = AVAudioFormat(commonFormat: .pcmFormatFloat32, sampleRate: sampleRate, channels: AVAudioChannelCount(numberOfChannels), interleaved: false)
let buffer = AVAudioPCMBuffer(pcmFormat: audioFormat!, frameCapacity: AVAudioFrameCount(length))!
buffer.frameLength = buffer.frameCapacity
for channelIndex in 0...numberOfChannels - 1 {
guard let channel: UnsafeMutablePointer<Float> = buffer.floatChannelData?[channelIndex] else { return nil }
for pointerIndex in 0...length - 1 {
let pointer: UnsafeMutablePointer<Float> = channel.advanced(by: pointerIndex)
pointer.pointee = 100
}
}
return buffer
}
}Does anyone knows how to convert a CMSampleBuffer to AVAudioPCMBuffer and back again? I assume there is no other way if I want to interact with AVAudioEngine, am I right?
fsoc
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