1

I create an AudioQueue in the following steps.

  1. Create a new output with AudioQueueNewOutput
  2. Add a property listener for the kAudioQueueProperty_IsRunning property
  3. Allocate my buffers with AudioQueueAllocateBuffer
  4. Call AudioQueuePrime
  5. Call AudioQueueStart

The problem is, when i call AudioQueuePrime it outputs following error on the console

AudioConverterNew returned -50
Prime failed (-50); will stop (11025/0 frames)

What's wrong here?

PS:

  1. I got this error on iOS (Device & Simulator)
  2. The output callback installed when calling AudioQueueNewOutput is never called!
  3. The file is valid and the AudioStreamBasicDescription does match the format (AAC)
  4. I tested the file with Mat's AudioStreamer and it seems to work there

Sample Init Code:

// Get the stream description from the first sample buffer
OSStatus err = noErr;

EDSampleBuffer *firstBuf = [sampleBufs objectAtIndex:0];
AudioStreamBasicDescription asbd = firstBuf.streamDescription;

// TODO: remove temporary format setup, just to ensure format for now
asbd.mSampleRate = 44100.00;
asbd.mFramesPerPacket = 1024; // AAC default
asbd.mChannelsPerFrame = 2;

pfcc(asbd.mFormatID);
// -----------------------------------

// Create a new output
err = AudioQueueNewOutput(&asbd, _audioQueueOutputCallback, self, NULL, NULL, 0, &audioQueue);
if (err) {
    [self _reportError:kASAudioQueueInitializationError];
    goto bail;
}

// Add property listener for queue state
err = AudioQueueAddPropertyListener(audioQueue, kAudioQueueProperty_IsRunning, _audioQueueIsRunningCallback, self);
if (err) {
    [self _reportError:kASAudioQueuePropertyListenerError];
    goto bail;
}

// Allocate a queue buffers
for (int i=0; i<kAQNumBufs; i++) {
    err = AudioQueueAllocateBuffer(audioQueue, kAQDefaultBufSize, &queueBuffer[i]);
    if (err) {
        [self _reportError:kASAudioQueueBufferAllocationError];
        goto bail;
    }
}

// Prime and start
err = AudioQueuePrime(audioQueue, 0, NULL);
if (err) {
    printf("failed to prime audio queue %ld\n", err);
    goto bail;
}

err = AudioQueueStart(audioQueue, NULL);
if (err) {
    printf("failed to start audio queue %ld\n", err);
    goto bail;
}

These are the format flags from the audio file stream

rate: 44100.000000
framesPerPacket: 1024
format: aac 
bitsPerChannel: 0
reserved: 0
channelsPerFrame: 2
bytesPerFrame: 0
bytesPerPacket: 0
formatFlags: 0
cookieSize 39

1 Answers1

4
AudioConverterNew returned -50
Prime failed (-50); will stop (11025/0 frames)

What's wrong here?

You did it wrong.

No, really. That's what that error means, and that's ALL that error means.

That's why paramErr (-50) is such an annoying error code: It doesn't say a damn thing about what you (or anyone else) did wrong.

The first step to formulating guesses as to what it's complaining about is to find out what function returned that error. Change your _reportError: method to enable you to log the name of the function that returned the error. Then, log the parameters you're passing to that function and figure out why it's of the opinion that those parameters to that function don't make sense.

My own wild guess is that it's because the values you forced into the ASBD don't match the characteristics of the sample buffer. The log output you included in your question says “11025/0 frames”; 11025 is a common sample rate (but different from 44100). I assume you'd know what the 0 refers to.

Peter Hosey
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  • If it were that simple i would not ask. The functions returning the error are either `AudioQueuePrime` or `AudioQueueStart`. The `AudioStreamBasicDescription` is accurate for the file i currently use (checked it with the `AudioFileStream` API, and Quicktime) –  Nov 07 '10 at 15:53
  • I attached the parsed format flags from the audio file stream –  Nov 07 '10 at 15:56
  • Erik Aigner: I'm not faulting you; it's a terribly vague error code. As I said, all that error code says is “you did it wrong”. That sucks. Anyway, like I said, you should determine exactly which function is returning the error. Also, note that sometimes one function failing earlier up can cause later ones to fail. – Peter Hosey Nov 07 '10 at 16:01
  • I know that and i have checked it countless times if a function failed before that one. But they don't :( –  Nov 07 '10 at 16:03
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    I got it after 7 hours of tinkering around ... it was a fault in the `EDSampleBuffer` class that caused uninitialized `AudioStreamBasicDescription` struct values to be copied, thus resulting in some random description parameters –  Nov 07 '10 at 17:57