how to encode/decode speex with AudioQueue in ios

If anyone have some experience that encode/decode speex audio format with AudioQueue?

I have tried to implement it by editing the SpeakHere sample. But not success!

From the apple API document, AudioQueue can support codec, but I can't found any sample. Could anyone give me some suggestion? I already compiled speex codec successfully in m开发者_如何学Goy project in XCode 4.

---

in the apple sample code "SpeakHere" you can do some thing like this:

AudioQueueNewInput(
                                     &mRecordFormat,
                                     MyInputBufferHandler,
                                     this /* userData */,
                                     NULL /* run loop */,
                                     NULL /* run loop mode */,
                                     0 /* flags */, &mQueue)

you can do some thing in function "MyInputBufferHandler" like

[self encoder:(short *)buffer->mAudioData count:buffer->mAudioDataByteSize/sizeof(short)];

the encoder function like:

while ( count >= samplesPerFrame )
    {
        speex_bits_reset( &bits );

        speex_encode_int( enc_state, samples, &bits ); 

        static const unsigned maxSize = 256;
        char data[maxSize];
        unsigned size = (unsigned)speex_bits_write( &bits, data, maxSize );
        /*
                    do some thing... for example :send to server
        */

        samples += samplesPerFrame;
        count -= samplesPerFrame;
    }

This is the general idea.Of course fact is hard, but you can see some open source of VOIP, maybe can help you. good luck.

---

You can achieve all that with FFMPEG and then play it as PCM with AudioQueue. The building of the FFMPEG library is not so painless but the whole decode/encode process is not that hard :)

FFMPEG official site SPEEX official site

You will have to download the libs and build them yourself and then you will have to include them into FFMPEG and build it.

---

Below is the Code For Capturing Audio using audioqueue and encode (wide-band) using speex (For Better Quality of Audio You can encode data in separate Thread , Change your sample size according to your capture format).

Audio format

    mSampleRate = 16000;
    mFormatID = kAudioFormatLinearPCM;
    mFramesPerPacket = 1;
    mChannelsPerFrame = 1;
    mBytesPerFrame = 2;
    mBytesPerPacket = 2;
    mBitsPerChannel = 16;
    mReserved = 0;
    mFormatFlags = kLinearPCMFormatFlagIsSignedInteger | kLinearPCMFormatFlagIsPacked; 

Capture callback

    void CAudioCapturer::AudioInputCallback(void *inUserData, 
                           AudioQueueRef inAQ, 
                           AudioQueueBufferRef inBuffer, 
                           const AudioTimeStamp *inStartTime, 
                           UInt32 inNumberPacketDescriptions, 
                           const AudioStreamPacketDescription *inPacketDescs)
    {
    CAudioCapturer *This = (CMacAudioCapturer *)inUserData;

int len = 640;
char data[640];
char *pSrc = (char *)inBuffer->mAudioData;

while (len <= inBuffer->mAudioDataByteSize) 
{
    memcpy(data,pSrc,640);
    int enclen = encode(buffer,encBuffer);
    len=len+640;

    pSrc+=640; // 640 is the frame size for WB in speex (320 short)
}

AudioQueueEnqueueBuffer(This->m_audioQueue, inBuffer, 0, NULL);
    }

speex encoder

    int encode(char *buffer,char *pDest)
    {
int nbBytes=0;
speex_bits_reset(&encbits);

speex_encode_int(encstate, (short*)(buffer)  , &encbits);

nbBytes = speex_bits_write(&encbits, pDest ,640/(sizeof(short))); 

return nbBytes;
    }