Speex dev - Apr 2010 - Another newbie question on encoding

Hi,

I'm very sorry if those questions are repeated over and over, but I
cannot find a solution on the net.

I try to use speex to encode/decode voice to send over the network.
My doubts are:

1. The Bits_Per_Sample I use, are independent from the speex
encoding/decoding? (So...can I use 8, 16, 24..and so on?)

2. If I have this situation:

SAMPLE RATE.....: 8000
BITS PER SAMPLE.: 16
CHANNELS........: 1
DATA TYPE.......: float

And I need to encode a buffer of 640 PCM float frames, the following
Encode method is correct?

Thanks in advance for the help!
Daniele.



class CSpeexCodec
{
public:

  enum ESpeexCodecType
  {
    SC_ENCODER,
    SC_DECODER
  };

  enum ESpeexCodecMode
  {
    SC_NARROWBAND,    //  8 kHz
    SC_WIDEBAND,      // 16 kHz
    SC_ULTRAWIDEBAND  // 32 kHz
  };

  CSpeexCodec();
  ~CSpeexCodec();

  BOOL  Init();
  UINT  Encode( sample_type *inBuff, char **outBuff, UINT BufferFrames );

private:
  SpeexBits       spx_bits_;
  void*           spx_state_;
  UINT            spx_quality_;
  UINT            frameSize_;
  char*           outBuffer_;
};


BOOL CSpeexCodec::Init()
{
  spx_state_ = speex_encoder_init(&speex_nb_mode);
  speex_encoder_ctl(spx_state_, SPEEX_GET_FRAME_SIZE, &frameSize_);
  // Create the output buffer
  outBuffer_ = new char[frameSize_];
  speex_bits_init(&spx_bits_);
}


UINT CSpeexCodec::Encode( float *inBuff,
                          char **outBuff,
                          UINT BufferFrames )
{
  INT nBytes = 0;
  float *pBuff = inBuff;

  if (!spx_state_) return 0;

  while (BufferFrames>0)
  {
    speex_bits_reset(&spx_bits_);
    speex_encode(spx_state_, pBuff, &spx_bits_);
    nBytes += speex_bits_write(&spx_bits_, outBuffer_, frameSize_);
    pBuff  += frameSize_;
    BufferFrames -= frameSize_;
  }
  // Point the outBuff to the internal buffer
  *outBuff = outBuffer_;
  return nBytes;
};

Il 13/04/2010 16:57, Daniele Barzotti wrote:
> 
> 2. If I have this situation:
> 
> SAMPLE RATE.....: 8000
> BITS PER SAMPLE.: 16
> CHANNELS........: 1
> DATA TYPE.......: float
> 
> And I need to encode a buffer of PCM float frames...
I hope that someone can help me, because I cannot understand where I
wrong, and I need to know if the mistake is in the encode/decode or in
another part of my code

I try to :
1. acquire audio from mic
2. encode it
3. send to a loopback VoIP session
4. decode it
5. playback to speakers

But I get no sound (while, without using the encode/decode all works)
This is my code:


UINT CSpeexCodec::Encode( float *inBuff,
                          const char **outBuff,
                          UINT BufferFrames )
{
  INT nbBytes  = 0;
  float *pBuff = inBuff;

  if (!spx_state_) return 0;
  if (spx_type_ != SC_ENCODER) return 0;

  EncOutBuffer_.Recycle();
  speex_bits_reset(&spx_bits_);

  // The manual says that I have to call speex_encode many times before
  // calling speex_bits_write

  while (BufferFrames>0)
  {
    speex_encode(spx_state_, pBuff, &spx_bits_);
    // Move the pointers ahead of a frame size
    pBuff += spx_frame_size_;
    // Substract the amount of 1 frame from
    BufferFrames -= spx_frame_size_;
  }
  nbBytes = speex_bits_write(&spx_bits_,
                             spx_enc_frame_,
                             spx_frame_size_);

  // Save the speex frame into the buffer
  EncOutBuffer_.Write((void*)spx_enc_frame_, nbBytes);

  // Point the outBuff to the internal buffer
  *outBuff = (char*)EncOutBuffer_.GetRawData();
  return nbBytes;
};

//----------------------------------------------------------------------------

UINT CSpeexCodec::Decode( char *inBuff,
                          UINT BuffLen,
                          const sample_type **outBuff )
{
  if ( (!spx_state_) ||
       (!outBuff) ||
       (spx_type_ != SC_DECODER) ) return 0;

  INT   nbBytes = 0;
  UINT  nbBytesWritten = 0;

  DecOutBuffer_.Recycle();

  speex_bits_reset(&spx_bits_);
  speex_bits_read_from(&spx_bits_, inBuff, BuffLen);
  nbBytes = speex_bits_remaining(&spx_bits_);

  while (nbBytes>0)
  {
    if ( speex_decode(spx_state_, &spx_bits_, spx_dec_frame_) != 0 )
      break;
    nbBytes = speex_bits_remaining(&spx_bits_);
    // Save the speex frame into the buffer
    DecOutBuffer_.Write(spx_dec_frame_, spx_frame_size_);
    nbBytesWritten += spx_frame_size_;
  }

  // Point the outBuff to the internal buffer
  *outBuff = DecOutBuffer_.GetTypedData();
  return nbBytesWritten;
};