[Mplayer-dvb] LPCM PES

[mocm at convergence.de]

Hi, 
here are some tips for the LPCM PES that you send to the DVB card.
1) Since it is an audio PES it can't have a DTS, so if you have a
   timestamp, you only need the PTS. So  pes_header[8]=5;
   and leave out the pes_header bytes 14 - 18.
   That leaves you with either payload_size+=10; without PTS or 
   payload_size+=15;. Thats the 3 bytes from the header after the
   length plus the 7 bytes of the lpcm header and with or without the
   5 bytes of the PTS.

2) Don't write a PTS, if you don't have one. If yu have a timestamp
   for the MPEG or AC3 frame, then use that for the first resulting
   LPCM PES and leave all others empty.

3) The LPCM header is as follows:
   id                                                     8 bit
   number of frames                                       8 bit
   first acces unit pointer, i.e. start of audio frame   16 bit
   audio emphasis on-off                                  1 bit
   audio mute on-off                                      1 bit
   reserved                                               1 bit
   audio frame number                                     5 bit
   quantization word length                               2 bit
   audio sampling frequency (48khz = 0, 96khz = 1)        2 bit
   reserved                                               1 bit
   number of audio channels - 1 (e.g. stereo = 1)         3 bit
   dynamic range control (0x80 if off)                    8 bit

   The driver for the DVB card ignores all but the sample frequency
   bits. The Margi driver probably needs everything set correctly, but
   I can't test it right now. 

4) The DVB driver only takes LPCM PES with length < 2048 including the
   first 6 header bytes.

Hope that helps.

Marcus