问题
I have a RemoteIO unit configured with AVAudioSessionCategoryPlayAndRecord. I find some strange behavior in it. I open the app, and immediately close it before audioUnit initializes fully (it actually initializes in background as I quit the app too soon). Next I bring the app to foreground and immediately on relaunch, I see AudioUnitRender failing with error -50 continuously. I find inNumberFrames to be 1115 and it fails whenever this number is odd.
func recordingCallback(inRefCon:UnsafeMutableRawPointer,
ioActionFlags:UnsafeMutablePointer<AudioUnitRenderActionFlags>,
inTimeStamp:UnsafePointer<AudioTimeStamp>,
inBusNumber:UInt32,
inNumberFrames:UInt32,
ioData:UnsafeMutablePointer<AudioBufferList>?) -> OSStatus
{
let controller = unsafeBitCast(inRefCon, to: MicrophoneOutput.self)
let listPtr = controller.audioBufferList.unsafeMutablePointer
let buffers = UnsafeBufferPointer<AudioBuffer>(start: &listPtr.pointee.mBuffers, count: Int(listPtr.pointee.mNumberBuffers))
for var buf in buffers {
buf.mDataByteSize = inNumberFrames * UInt32(sampleWordSize)
}
let status = AudioUnitRender(controller.audioUnit!, ioActionFlags, inTimeStamp, inBusNumber, inNumberFrames, listPtr)
if noErr != status {
print("Error \(status)");
NSLog("\(AVAudioSession.sharedInstance().currentRoute.inputs[0])")
fatalError("Render status \(status)")
// return status;
}
return noErr
}
Strangely, if I hardcode inNumberFrames to be 1114 in AudioUnitRender call, it succeeds! Does anyone know what is going on? The pattern is as soon as the app resumes from background, there is a route change notification, and then the first sample in callback is of length 1114 frames but the one next to it has 1115 frames which fails.
回答1:
It turned out it was a programming error due to misunderstandings in Swift language. The line that was culprit was this:
for var buf in buffers {
buf.mDataByteSize = inNumberFrames * UInt32(sampleWordSize)
}
This answer provides more detail - Swift vs Objective C pointer manipulation issue
来源:https://stackoverflow.com/questions/52061575/audiounitrender-error-50-with-odd-length-buffers