Error -50 from AudioUnitRender - objective-c

Question

I'm getting error -50 (invalid parameters) from AudioUnitRender in the following context. I'm using this Pitch Detector sample app as my starting point, and it works fine. The only major difference in my project is that I'm also using the Remote I/O unit for audio output. The audio output works fine. Here is my input callback and my initialization code (with error checking removed for brevity). I know it's a lot but error -50 really gives me very little information as to where the problem might be.
Input callback:
OSStatus inputCallback( void* inRefCon,
AudioUnitRenderActionFlags *ioActionFlags,
const AudioTimeStamp *inTimeStamp,
UInt32 inBusNumber,
UInt32 inNumberFrames,
AudioBufferList *ioData) {
WBAudio* audioObject= (WBAudio*)inRefCon;
AudioUnit rioUnit = audioObject->m_audioUnit;
OSStatus renderErr;
UInt32 bus1 = 1;
renderErr = AudioUnitRender(rioUnit, ioActionFlags,
inTimeStamp, bus1, inNumberFrames, audioObject->m_inBufferList );
if (renderErr < 0) {
return renderErr; // breaks here
}
return noErr;
} // end inputCallback()
Initialization:
- (id) init {
self= [super init];
if( !self ) return nil;
OSStatus result;
//! Initialize a buffer list for rendering input
size_t bytesPerSample;
bytesPerSample = sizeof(SInt16);
m_inBufferList = (AudioBufferList *)malloc(sizeof(AudioBuffer));
m_inBufferList->mNumberBuffers = 1;
m_inBufferList->mBuffers[0].mNumberChannels = 1;
m_inBufferList->mBuffers[0].mDataByteSize = 512*bytesPerSample;
m_inBufferList->mBuffers[0].mData = calloc(512, bytesPerSample);
//! Initialize an audio session to get buffer size
result = AudioSessionInitialize(NULL, NULL, NULL, NULL);
UInt32 audioCategory = kAudioSessionCategory_PlayAndRecord;
result = AudioSessionSetProperty(kAudioSessionProperty_AudioCategory, sizeof(audioCategory), &audioCategory);
// Set preferred buffer size
Float32 preferredBufferSize = static_cast<float>(m_pBoard->m_uBufferSize) / m_pBoard->m_fSampleRate;
result = AudioSessionSetProperty(kAudioSessionProperty_PreferredHardwareIOBufferDuration, sizeof(preferredBufferSize), &preferredBufferSize);
// Get actual buffer size
Float32 audioBufferSize;
UInt32 size = sizeof (audioBufferSize);
result = AudioSessionGetProperty(kAudioSessionProperty_CurrentHardwareIOBufferDuration, &size, &audioBufferSize);
result = AudioSessionSetActive(true);
//! Create our Remote I/O component description
AudioComponentDescription desc;
desc.componentType= kAudioUnitType_Output;
desc.componentSubType= kAudioUnitSubType_RemoteIO;
desc.componentFlags= 0;
desc.componentFlagsMask= 0;
desc.componentManufacturer= kAudioUnitManufacturer_Apple;
//! Find the corresponding component
AudioComponent outputComponent = AudioComponentFindNext(NULL, &desc);
//! Create the component instance
result = AudioComponentInstanceNew(outputComponent, &m_audioUnit);
//! Enable audio output
UInt32 flag = 1;
result = AudioUnitSetProperty( m_audioUnit, kAudioOutputUnitProperty_EnableIO, kAudioUnitScope_Output, kOutputBus, &flag, sizeof(flag));
//! Enable audio input
result= AudioUnitSetProperty( m_audioUnit, kAudioOutputUnitProperty_EnableIO, kAudioUnitScope_Input, kInputBus, &flag, sizeof(flag));
//! Create our audio stream description
m_audioFormat.mSampleRate= m_pBoard->m_fSampleRate;
m_audioFormat.mFormatID= kAudioFormatLinearPCM;
m_audioFormat.mFormatFlags= kAudioFormatFlagIsSignedInteger | kAudioFormatFlagIsPacked;
m_audioFormat.mFramesPerPacket= 1;
m_audioFormat.mChannelsPerFrame= 1;
m_audioFormat.mBitsPerChannel= 16;
m_audioFormat.mBytesPerPacket= 2;
m_audioFormat.mBytesPerFrame= 2;
//! Set the stream format
result = AudioUnitSetProperty( m_audioUnit, kAudioUnitProperty_StreamFormat, kAudioUnitScope_Input, kOutputBus, &m_audioFormat, sizeof(m_audioFormat));
result = AudioUnitSetProperty(m_audioUnit, kAudioUnitProperty_StreamFormat,
kAudioUnitScope_Output,
kInputBus, &m_audioFormat, sizeof(m_audioFormat));
//! Set the render callback
AURenderCallbackStruct renderCallbackStruct= {0};
renderCallbackStruct.inputProc= renderCallback;
renderCallbackStruct.inputProcRefCon= m_pBoard;
result = AudioUnitSetProperty(m_audioUnit, kAudioUnitProperty_SetRenderCallback, kAudioUnitScope_Global, kOutputBus, &renderCallbackStruct, sizeof(renderCallbackStruct));
//! Set the input callback
AURenderCallbackStruct inputCallbackStruct = {0};
inputCallbackStruct.inputProc= inputCallback;
inputCallbackStruct.inputProcRefCon= self;
result= AudioUnitSetProperty( m_audioUnit, kAudioOutputUnitProperty_SetInputCallback, kAudioUnitScope_Input, kOutputBus, &inputCallbackStruct, sizeof( inputCallbackStruct ) );
//! Initialize the unit
result = AudioUnitInitialize( m_audioUnit );
return self;
}

Answer 1

You are allocating the m_inBufferList as:
m_inBufferList = (AudioBufferList *)malloc(sizeof(AudioBuffer));
This should be:
m_inBufferList = (AudioBufferList *)malloc(sizeof(AudioBufferList) + sizeof(AudioBuffer) * numberOfBuffers); //numberOfBuffers in your case is 1
Maybe this can solve your problem.

Answer 2

Error -50 in the develop doc means params error ，
make sure you have pass the right params in AudioUnitRender。
check the stream format and your unit

Answer 3

I agree with Kurt Pattyn that the allocation of m_inBufferList is incorrect, and might be the cause of -50 bad param error.
Except I think that for a single buffer it should be
(AudioBufferList *)malloc(sizeof(AudioBufferList)
My evidence is the following sizes and the code from Adamson & Avila below.
(lldb) sizeof(AudioBufferList)
24
(lldb) po sizeof(AudioBuffer)
16
(lldb) po offsetof(AudioBufferList, mBuffers[0])
8
According to Chris Adamson & Kevin Avila in Learning Core Audio:
// Allocate an AudioBufferList plus enough space for
// array of AudioBuffers
UInt32 propsize = offsetof(AudioBufferList, mBuffers[0]) +
(sizeof(AudioBuffer) * player->streamFormat.mChannelsPerFrame);
// malloc buffer lists
player->inputBuffer = (AudioBufferList *)malloc(propsize);
player->inputBuffer->mNumberBuffers = player->streamFormat.mChannelsPerFrame;
// Pre-malloc buffers for AudioBufferLists
for(UInt32 i =0; i< player->inputBuffer->mNumberBuffers ; i++) {
player->inputBuffer->mBuffers[i].mNumberChannels = 1;
player->inputBuffer->mBuffers[i].mDataByteSize = bufferSizeBytes;
player->inputBuffer->mBuffers[i].mData = malloc(bufferSizeBytes);
}
Last but not least, I just happened upon this code with the following comment : )
//credit to TheAmazingAudioEngine for an illustration of proper audiobufferlist allocation.
// Google leads to some really really bad allocation code...
[other code]
sampleABL = malloc(sizeof(AudioBufferList) + (bufferCnt-1)*sizeof(AudioBuffer));
https://github.com/zakk4223/CocoaSplit/blob/master/CocoaSplit/CAMultiAudio/CAMultiAudioPCMPlayer.m#L203