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[linux-dvb] mpegtools: ts2ps and AC3

Mark Lehrer writes:
 > Hello there.  I am playing with an ATSC transport stream (1280x720 fps
 > w/AC3 sound); trying to convert it into a presentation stream for
 > further processing with transcode.
 > I am having some trouble with the sound - transcode does not seem to
 > recognize the sound that was apparently written to the presentation
 > stream by ts2ps.  The sound is stored in a PRIVATE_STREAM1, which
 > appears to be handled by the write_ipack routines.
 > I've been looking through the code for a little while here, and the
 > only suspicious thing that jumps out at me is that ps_pes() does not
 > have a handler for the PRIVATE_STREAM1 type; only the AUDIO_STREAM_*
 > and VIDEO_STREAM_* types.
 > I also noticed that the program never calls get_ac3info due to large
 > values for ac3_off; but I'm not sure if this is a big issue.
 > I am relatively new to MPEG - could someone give me a hint of what
 > to do to make the AC3 sound be acceptable for transcode?  I can
 > provide sample streams if that will help.
 > Thanks!
 > Mark

Try the dvb-mpegtools at
They should work with ATSC streams. I tried it with some sample
streams we got. I think there was some error I fixed recently, so that
it won't be corrected in the convergence CVS.
I could play the converted stream with mplayer and ntuxplayer (with -e
AC3 option).
The problem with the AC3 PES in ATSC is that they are different from
DVB PES. They don't need/have a separate stream id and some other
extra header information which can be found at the beginning of the
PRIVATE_STREAM1 payload in DVB PES. This information is not needed
for decoding, but expected by the demuxers of DVD players.


| Dr. Marcus O.C. Metzler        |                                   |
|            |        |

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