<html><head><style type="text/css"><!-- DIV {margin:0px;} --></style></head><body><div style="font-family:times new roman, new york, times, serif;font-size:12pt"><div>Hi,<br><br>I am developing a peer-to-peer video conference application which uses speex as a codec for the voice. <br><br>I am new to speex, so please bear with me if I asked the obvious. After I added the encode and decode function to my MFC app, I heard a constant background noise, even when no one is speaking into the microphone. <br><br>#define FRAME_SIZE 160<br><br>The application is coded in MFC C++. The record buffer is set to be the same as the FRAME_SIZE such that my callback function is called everytime 160 bytes of data is recorded.<br><br>Here's what I did in the initialisation (called only once).<br>m_waveFormatEx.wFormatTag =WAVE_FORMAT_PCM;<br>m_waveFormatEx.nChannels =1;<br>m_waveFormatEx.wBitsPerSample =8;<br>m_waveFormatEx.cbSize =0;<br>m_waveFormatEx.nSamplesPerSec =
8000;<br>m_waveFormatEx.nBlockAlign =1;<br>m_waveFormatEx.nAvgBytesPerSec = 8000;<br><br>int quality =8;<br>speex_bits_init(&bits);<br>enc_state = speex_encoder_init(&speex_nb_mode);<br>speex_encoder_ctl(enc_state, SPEEX_SET_QUALITY, &quality);<br><br><br>In my recording callback function<br>LRESULT RecordSound::OnSoundData(WPARAM wParam, LPARAM lParam)<br>{<br> ....<br> dataPtr = (char *)lpHdr ->lpData;<br> dataSize = (int)lpHdr ->dwBytesRecorded;<br><br> for(int k=0;k<FRAME_SIZE;k++)<br> input[k] = dataPtr[k]; //input is float[FRAME_SIZE]<br> <br> speex_bits_reset(&bits);<br> speex_encode(enc_state, input, &bits);<br> encByte = speex_bits_write(&bits, cbits, 200);<br><br> //send cbits to peer computer via sockets<br>}<br><br><br>In the
receiver's initialization function, I've initialized the speex_decoder.<br>speex_bits_init(&bits);<br>
dec_state = speex_decoder_init(&speex_nb_mode);<br><br>In the receiver's socket function, it reads from socket and store the data in cbits (char array).<br>{<br> speex_bits_read_from(&bits, cbits, retvalue); //retvalue is 38<br> speex_decode(dec_state, &bits, output); //where output is float array<br><br> for(int k=0;k<FRAME_SIZE;k++)<br> out[k] = output[k]; //out is a char array<br> <br> PostThreadMessage( WM_PLAYSOUND_PLAYBLOCK, FRAME_SIZE, (LPARAM)out );<br>}<br><br><br><br></div></div><br>
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