Question

Does anyone knows why after I apply this algorithm in c++ to reduce the volume of a pcm apears a white noise in the background?

for(int i = 0; i<pcm.length(); i+=2) {
   quint16 byte0 = pcm[i];
   quint16 byte1 = pcm[i+1];

   //merge byte0 and byte1
   qint16 n = (byte1 << 8) + byte0;

   n *= volume; // multiplier;

   //split n into byte0 and byte1
   byte1   = (n >> 8) & 255;
   byte0    = n & 255;

   //save the new values
   pcm[i] = byte0;
   pcm[i+1] = byte1;
}

Answer 1

After a long time, I come with the solution. The problem was the mode that I was merging the two bites.

 for(int i = 0; i<pcm.length(); i+=2) {
   quint16 byte0 = pcm[i];
   quint16 byte1 = pcm[i+1];

   //merge byte0 and byte1
   qint16 n = 0;
   n |= speakersRaw[j][i+1] & 0xFF;
   n <<= 8;
   n |= speakersRaw[j][i] & 0xFF;

   n *= volume; // multiplier;

   //split n into byte0 and byte1
   byte1   = (n >> 8) & 255;
   byte0    = n & 255;

   //save the new values
   pcm[i] = byte0;
   pcm[i+1] = byte1;
}