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我已经设置了音频格式为 kAudioFormatMPEG4AAC（我相信是 AAC-LC）的音频队列。我正在寻找一些代码来通过 RTP 发送这些 AAC 数据包（我只需要添加一个标头吗？）以及制作一个好的 SDP 的提示，因为我没有找到任何关于 iphone AAC 硬件编码器的文档。我试过这个没有成功：

-(OSStatus) initializeAQ{
    aqData.mDataFormat.mSampleRate = 44100;
    aqData.mDataFormat.mFormatID = kAudioFormatMPEG4AAC;
    aqData.mDataFormat.mFormatFlags = 0;
    aqData.mDataFormat.mBytesPerPacket = 0; // 0 for VBR
    aqData.mDataFormat.mFramesPerPacket = 1024;
    aqData.mDataFormat.mBytesPerFrame = 0; // 0 for compressed format
    aqData.mDataFormat.mChannelsPerFrame = 1;
    aqData.mDataFormat.mBitsPerChannel = 0; // 0 for compressed format   
    aqData.bufferByteSize = 0x1388; // quite random

    AudioQueueNewInput(&aqData.mDataFormat, HandleInputBuffer, &aqData, CFRunLoopGetMain(), kCFRunLoopCommonModes, 0, &aqData.mQueue);
    aqData.mCurrentPacket = 0;
    aqData.mIsRunning = true;

    //--- prepare set of audio queue buffers ---//
    for(int i = 0 ; i < nBuffer ; i++){
        AudioQueueAllocateBuffer(aqData.mQueue, aqData.bufferByteSize, &aqData.mBuffers[i]);
        AudioQueueEnqueueBuffer(aqData.mQueue, aqData.mBuffers[i], 0, NULL);
    }

    NSLog(@"starting audio queue");
    //--- start ---//
    return AudioQueueStart(aqData.mQueue, NULL);
}
static void HandleInputBuffer(
    void                                *aqData,
    AudioQueueRef                       inAq,
    AudioQueueBufferRef                 inBuffer,
    const AudioTimeStamp                *inStartTime,
    UInt32                              inNumPackets,
    const AudioStreamPacketDescription  *inPacketDesc
) {
    AQRecorderState *pAqData = (AQRecorderState*) aqData;
    if( inNumPackets == 0 && pAqData->mDataFormat.mBytesPerPacket != 0 ){
        inNumPackets = inBuffer->mAudioDataByteSize/pAqData->mDataFormat.mBytesPerPacket;
    }

    UInt32 x = 0;
    for(; x < inNumPackets ; x++){
        SInt64 offset = inPacketDesc[x].mStartOffset;
        UInt32 len = inPacketDesc[x].mDataByteSize;
        unsigned char *packet[len];
        bzero(packet, len);
        memcpy(packet,(unsigned char*)(inBuffer->mAudioData)+offset,len);
        NSData* data = [[NSData alloc]initWithBytes:packet length:len];
        //[s send:data];
        [s send:data withTime:inStartTime->mHostTime];
     }
     AudioQueueEnqueueBuffer(pAqData->mQueue,inBuffer,0,NULL);
}

send() 添加一个像这样的 RTP 标头并通过 udp 发送数据包。

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