Objective c: Send audio data in rtp packet via socket

Question

In my app, I have to capture microphone and send audio data in rtp packet. But I only see receive rtp data like iOS RTP live audio receiving or unanswered one.

I used following code with AsuncUdpSocket to sent audio data but it wasn't wrap in rtp packet. Is there any library to wrap my audio data into rtp packet?

initial AsyncUdpSocket:

 udpSender = [[GCDAsyncUdpSocket alloc] initWithDelegate:self delegateQueue:dispatch_get_main_queue()];

NSError *error;
[udpSender connectToHost:@"192.168.1.29" onPort:1024 error:&error];   

I send audio data in my playback callback function:

static OSStatus playbackCallback(void *inRefCon, 
                             AudioUnitRenderActionFlags *ioActionFlags, 
                             const AudioTimeStamp *inTimeStamp, 
                             UInt32 inBusNumber, 
                             UInt32 inNumberFrames, 
                             AudioBufferList *ioData) {    

/**
 This is the reference to the object who owns the callback.
 */
AudioProcessor *audioProcessor = (AudioProcessor*) inRefCon;

// iterate over incoming stream an copy to output stream
for (int i=0; i < ioData->mNumberBuffers; i++) { 
    AudioBuffer buffer = ioData->mBuffers[i];

    // find minimum size
    UInt32 size = min(buffer.mDataByteSize, [audioProcessor audioBuffer].mDataByteSize);

    // copy buffer to audio buffer which gets played after function return
    memcpy(buffer.mData, [audioProcessor audioBuffer].mData, size);

    // set data size
    buffer.mDataByteSize = size;

    //Send data to remote server      

    NSMutableData *data=[[NSMutableData alloc] init];
    Float32 *frame = (Float32*)buffer.mData;
    [data appendBytes:frame length:size];
    if ([udpSender isConnected])
    {
        [udpSender sendData:data withTimeout:-1 tag:1];
    }


}



return noErr;
} 

How do I accomplish this?

Thanks.

Answer 1

Finally, here's my solution.

Setup the microphone capture process:

-(void)open {
NSError *error;
m_capture = [[AVCaptureSession alloc]init];
AVCaptureDevice *audioDev = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeAudio];
if (audioDev == nil)
{
    printf("Couldn't create audio capture device");
    return ;
}
//m_capture.sessionPreset = AVCaptureSessionPresetLow;

// create mic device
AVCaptureDeviceInput *audioIn = [AVCaptureDeviceInput deviceInputWithDevice:audioDev error:&error];
if (error != nil)
{
    printf("Couldn't create audio input");
    return ;
}


// add mic device in capture object
if ([m_capture canAddInput:audioIn] == NO)
{
    printf("Couldn't add audio input");
    return ;
}
[m_capture addInput:audioIn];
// export audio data
AVCaptureAudioDataOutput *audioOutput = [[AVCaptureAudioDataOutput alloc] init];
[audioOutput setSampleBufferDelegate:self queue:dispatch_get_main_queue()];
if ([m_capture canAddOutput:audioOutput] == NO)
{
    printf("Couldn't add audio output");
    return ;
}


[m_capture addOutput:audioOutput];
[audioOutput connectionWithMediaType:AVMediaTypeAudio];
[m_capture startRunning];
return ;
}

Capture the microphone data:

-(void) captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection{
char szBuf[450];
int  nSize = sizeof(szBuf);

if (isConnect == YES)
{
if ([self encoderAAC:sampleBuffer aacData:szBuf aacLen:&nSize] == YES)
{
    [self sendAudioData:szBuf len:nSize channel:0];
}

}

Initial the socket

-(void)initialSocket{
    //Use socket
    printf("initialSocket\n");
    CFReadStreamRef readStream = NULL;
    CFWriteStreamRef writeStream = NULL;

    NSString *ip = @"192.168.1.147";   //Your IP Address
    uint *port = 22133;

    CFStreamCreatePairWithSocketToHost(kCFAllocatorDefault, (__bridge CFStringRef)ip, port, &readStream,  &writeStream);
    if (readStream && writeStream) {
    CFReadStreamSetProperty(readStream, kCFStreamPropertyShouldCloseNativeSocket, kCFBooleanTrue);
    CFWriteStreamSetProperty(writeStream, kCFStreamPropertyShouldCloseNativeSocket, kCFBooleanTrue);

    iStream = (__bridge NSInputStream *)readStream;
    [iStream setDelegate:self];
    [iStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
    [iStream open];

    oStream = (__bridge NSOutputStream *)writeStream;
    [oStream setDelegate:self];
    [oStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
    [oStream open];
    }
}

Send data to socket when capture the data form microphone.

-(void)sendAudioData: (char *)buffer len:(int)len channel:(UInt32)channel
{
    Float32 *frame = (Float32*)buffer;
    [globalData appendBytes:frame length:len];

    if (isConnect == YES)
    {
        if ([oStream streamStatus] == NSStreamStatusOpen)
        {
            [oStream write:globalData.mutableBytes maxLength:globalData.length];


            globalData = [[NSMutableData alloc] init];

        }
    }

}

Hope this will help someone.