I'm using speex to encode some audio data and send it over UDP, and decode it on the other side. I ran a few tests with speex, and noticed that if I decode a packet straight after I encoded it, the decoded data is in no way close to the original data. Most of the bytes at the start of the buffer are 0. So when I decode the audio sent over UDP, all I get is noise. This is how I am encoding the audio:
bool AudioEncoder::encode( float *raw, char *encoded_bits )
{
for ( size_t i = 0; i < 256; i++ )
this->_rfdata[i] = raw[i];
speex_bits_reset(&this->_bits);
speex_encode(this->_state, this->_rfdata, &this->_bits);
int bytesWritten = speex_bits_write(&this->_bits, encoded_bits, 512);
if (bytesWritten)
return true;
return false;
}
this is how I am decoding the audio:
float *f = new float[256];
// recvbuf is the buffer I pass to my recv function on the socket
speex_bits_read_from(&this->_bits, recvbuf, 512);
speex_decode(this->state, &this->_bits, f);
I've check out the docs, and most of my code comes from the example encoding/decoding sample from the speex website. I'm not sure what I'm missing here.
I found the reason the encoded data was so different. There is the fact it's a lossy compression as Paulo Scardine said, and also that speex only works with 160 frames, so when getting data from portaudio to speex, it needs to be by "packets" of 160 frames.