How to encode / decode speex using AudioQueue in ios

Question

If anyone has experience that encodes / decodes speex audio format using AudioQueue?

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

From the Apple API document, AudioQueue may support the codec, but I cannot find a sample. Can someone give me some suggestion? I already compiled the speex codec in my project in Xcode 4.

Answer 1

in the apple SpeakHere code example, you can do something like this:

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

you can do something in the function "MyInputBufferHandler", for example

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

encoder function, for example:

 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 a general idea. Of course, this is difficult, but you can see some kind of open source VOIP, maybe it can help you. good luck.

Answer 2

You can achieve all this with FFMPEG and then play it as PCM with AudioQueue. Building the FFMPEG library is not so painless, but the whole decoding / coding process is not so difficult :)

Official site FFMPEG Official site SPEEX

You will have to download the libraries and create them yourself, and then you will have to include them in FFMPEG and create them.

Answer 3

Below is the code for recording sound using an audio signal and encoding (broadband) using speex (For better sound quality, you can encode data in a separate stream, resize the sample 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; 

Callback capture

  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; }