[Linphone-developers] alaw codec in mediastreamer2

[Yao-Chung Chang]

Currently, I'm working on writing a msfilter to hook with TI DSP . I
trace the source code of alaw.c and there is a snippet of code that I
can't understand.


alaw_enc_process ()
{
   .....
   MSBufferizer *bz = dt->bz;
   uint8_t buffer[2240];
   int frame_per_packet = 2;
   int size_of_pcm = 320;

   if (dt->ptime >= 10) {
       frame_per_packet = dt->ptime /10;
   }

   if (frame_per_packet <= 0)
          frame_per_packet = 1;
   if (frame_per_packet > 14) /* 7*20 == 140 ms max */
          frame_per_packet=14;

   size_of_pcm = 160*frame_per_packet; /*ex: for 20ms -> 160*2 == 320

   ....
}


My question is
1.how the buffer size, and frame_per_packet size is determined?
and why the size_of_pcm is 160 * frame_per_packet?
2. what the purpose of bufferizer?

                             Regards,
                                 ycchang