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iosobjective-ccore-audioezaudio

EZAudio framework -"Error: Couldn't initialize output unit ('fmt?')"

I am using EZAudio framework (https://github.com/syedhali/EZAudio) and when trying to initialize my output with a custom AudioStreamBasicDescription like so...

- (void)openMediaPlayer {
    // Initialize the EZOutput instance and assign it a delegate to provide the output audio data
    AudioStreamBasicDescription audioDesc;
    audioDesc.mFormatID = kAudioFormatLinearPCM;
    audioDesc.mSampleRate = 44100;
    audioDesc.mChannelsPerFrame = 2;
    audioDesc.mBytesPerFrame = 4;
    audioDesc.mFramesPerPacket = 1;
    audioDesc.mBytesPerPacket = 4;
    audioDesc.mBitsPerChannel = 16;
    audioDesc.mReserved = 0;
    self.output = [EZOutput outputWithDataSource:self withAudioStreamBasicDescription:audioDesc];
    self.currentAudioPieceIndex = 0;
}

I get the error "Error: Couldn't initialize output unit ('fmt?')"

What does this mean? AudioDesc is set with sane defaults for PCM 16 bit stereo audio.

Update: When I use the debugger I found I was getting OSStatus 1718449215.

Solution

  • It turns out you have to set 

    audioDesc.mFormatFlags = kAudioFormatFlagIsPacked | kAudioFormatFlagIsSignedInteger;

    When your audio format is PCM.