[Speex-dev] Integrating speex with VideoNet application: Constantbackground noise

[Carine Liang]

Hi John,

Thanks for your reply. 

Yes, my output device is in 8-bit mode, same as my input mode. I'm actually working in char (8 bit) arrays. Is it necessary to work in signed short integers only? I changed all the short arrays in the example to char. 

Carine

----- Original Message ----
From: John Miles <jmiles at pop.net>
To: carineliang at yahoo.com.sg; speex-dev at xiph.org
Sent: Thursday, 2 November 2006 2:04:39 PM
Subject: RE: [Speex-dev] Integrating speex with VideoNet application: Constantbackground noise



 
DIV {
MARGIN:0px;}



At 
first glance it looks like you are opening the output device in 8-bit mode (m_waveFormatEx.wBitsPerSample 
=8;).  You will need to use 16-bit 
mode if you expect to write an array of signed short integers to the audio 
buffer.  8-bit PCM is an unsigned mode, no longer used much these 
days.

 

Also, 
a good debugging trick is to include something like this in your output sample 
processing loop:

 

    static FILE *hack = 
fopen("test.raw","wb");

    fwrite(output, 2, FRAME_SIZE, 
hack);

 

After your app is closed, there will be a file called "test.raw" in 
its working directory, which you can load into Sound Forge or a similar audio 
editing package for closer inspection without relying on your output 
buffers and playback code to work properly.  

 

-- 
john

RAD 
Game Tools


  -----Original Message-----
From: speex-dev-bounces at xiph.org 
  [mailto:speex-dev-bounces at xiph.org]On Behalf Of Carine 
  Liang
Sent: Wednesday, November 01, 2006 9:40 PM
To: 
  speex-dev at xiph.org
Subject: Re: [Speex-dev] Integrating speex with 
  VideoNet application: Constantbackground noise



  
  Hi,

Can 
  someone please help me with my problem below. Any suggestions is appreciated. 
  

thanks,
Carine


  ----- 
  Original Message ----
From: Carine Liang 
  <carineliang at yahoo.com.sg>
To: speex-dev at xiph.org; 
  speex-dev at xiph.org
Sent: Tuesday, 31 October 2006 1:05:49 PM
Subject: 
  [Speex-dev] Integrating speex with VideoNet application: Constant background 
  noise


  
  Hi,

I am developing a peer-to-peer video conference application 
  which uses speex as a codec for the voice. 

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. 

#define FRAME_SIZE 
  160

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.

Here's what I did in the initialisation 
  (called only once).
m_waveFormatEx.wFormatTag 
  =WAVE_FORMAT_PCM;
m_waveFormatEx.nChannels 
  =1;
m_waveFormatEx.wBitsPerSample =8;
m_waveFormatEx.cbSize 
  =0;
m_waveFormatEx.nSamplesPerSec = 8000;
m_waveFormatEx.nBlockAlign 
  =1;
m_waveFormatEx.nAvgBytesPerSec = 8000;

int quality 
  =8;
speex_bits_init(&bits);
enc_state = 
  speex_encoder_init(&speex_nb_mode);
speex_encoder_ctl(enc_state, 
  SPEEX_SET_QUALITY, &quality);


In my recording callback 
  function
LRESULT RecordSound::OnSoundData(WPARAM wParam, LPARAM 
  lParam)
{
 ....
    dataPtr = (char *)lpHdr 
  ->lpData;
    dataSize = (int)lpHdr 
  ->dwBytesRecorded;

    for(int 
  k=0;k<FRAME_SIZE;k++)
       input[k] = 
  dataPtr[k];     //input is 
  float[FRAME_SIZE]
    
    
  speex_bits_reset(&bits);
    speex_encode(enc_state, 
  input, &bits);
    encByte = speex_bits_write(&bits, 
  cbits, 200);

    //send cbits to peer computer via 
  sockets
}


In the receiver's initialization function, I've 
  initialized the speex_decoder.
speex_bits_init(&bits);
dec_state = 
  speex_decoder_init(&speex_nb_mode);

In the receiver's socket 
  function, it reads from socket and store the data in cbits (char 
  array).
{
    speex_bits_read_from(&bits, cbits, 
  retvalue); //retvalue is 38
    speex_decode(dec_state, 
  &bits, output); //where output is float array

    
  for(int k=0;k<FRAME_SIZE;k++)
       out[k] = 
  output[k];  //out is a char array
    
   
  PostThreadMessage( WM_PLAYSOUND_PLAYBLOCK, FRAME_SIZE, (LPARAM)out 
  );
}







  
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