Pass through CMSampleBufferRef data to audio output jack - ios

Question

I am developing one app in which I need to pass through audio capturing through output audio jack at the same time record and save video.
I have looked into aurio touch apple sample code and implemented audio passthrough.
I have also implemented the video recording through AVCaptureSession.
Above both functionality individually done and works pefectly.
But when I merge functionality audio pass through not working because of audio session of the AVCapturesession.
I have also tried to pass through audio data which I am getting from AVCaptureSession delegate methods. Below is my code :
OSStatus err = noErr;
AudioBufferList audioBufferList;
CMBlockBufferRef blockBuffer;
CMSampleBufferGetAudioBufferListWithRetainedBlockBuffer(sampleBuffer, NULL, &audioBufferList, sizeof(audioBufferList), NULL, NULL, 0, &blockBuffer);
CMItemCount numberOfFrames = CMSampleBufferGetNumSamples(sampleBuffer); // corresponds to the number of CoreAudio audio frames
currentSampleTime += (double)numberOfFrames;
AudioTimeStamp timeStamp;
memset(&timeStamp, 0, sizeof(AudioTimeStamp));
timeStamp.mSampleTime = currentSampleTime;
timeStamp.mFlags |= kAudioTimeStampSampleTimeValid;
AudioUnitRenderActionFlags flags = 0;
aurioTouchAppDelegate *THIS = (aurioTouchAppDelegate *)[[UIApplication sharedApplication]delegate];
err = AudioUnitRender(self.rioUnit, &flags, &timeStamp, 1, numberOfFrames, &audioBufferList);
if (err) { printf("PerformThru: error %d\n", (int)err); }
But it is giving error. Please advise what can be done further as soon as possible. I have looked into so many docs and so many codes but couldn't find any solution. Please help..

Answer 1

Here's some better error handling code. What error does it return? You can look up the error description by searching for it in the documentation.
static void CheckError (OSStatus error, const char *operation) {
if (error == noErr) return;
char str[20] = {};
// see if it appears to be a 4 char code
*(UInt32*)(str + 1) = CFSwapInt32HostToBig(error);
if (isprint(str[1]) && isprint(str[2]) && isprint(str[3]) && isprint(str[4])) {
str[0] = str[5] = '\'';
str[6] = '\0';
} else {
sprintf(str, "%d", (int)error);
}
fprintf(stderr, "Error: %s(%s)\n", operation, str);
exit(1);
}
- (void)yourFunction
{
AudioBufferList audioBufferList;
CMBlockBufferRef blockBuffer;
CMSampleBufferGetAudioBufferListWithRetainedBlockBuffer(sampleBuffer, NULL, &audioBufferList, sizeof(audioBufferList), NULL, NULL, 0, &blockBuffer);
CMItemCount numberOfFrames = CMSampleBufferGetNumSamples(sampleBuffer); // corresponds to the number of CoreAudio audio frames
currentSampleTime += (double)numberOfFrames;
AudioTimeStamp timeStamp;
memset(&timeStamp, 0, sizeof(AudioTimeStamp));
timeStamp.mSampleTime = currentSampleTime;
timeStamp.mFlags |= kAudioTimeStampSampleTimeValid;
AudioUnitRenderActionFlags flags = 0;
aurioTouchAppDelegate *THIS = (aurioTouchAppDelegate *)[[UIApplication sharedApplication]delegate];
CheckError(AudioUnitRender(self.rioUnit, &flags, &timeStamp, 1, numberOfFrames, &audioBufferList),
"Error with AudioUnitRender");
}