[mythtv] MPEG2-MPEG2 transcoding: Illegal video stream

[Thomas Börkel]

HI!

Geoffrey Hausheer wrote:
> On 3/1/06, Thomas Börkel wrote:
>> The resulting files all play OK in MythTV, but other programs report
>> illegal video streams for 2 out of 5.
> Can you play them with mplayer?

Yes.

> In general, you need to cut the 1st 10MB or so off the front of the
> stream, ensure that that smaller file is still broken, then send it to
> me.

Is download also OK?

http://www.boerkel.de/test.mpg

I can also provide the first 10 MB of the original file, if necessary.

Repro:
mpeg2desc -v0 < test.mpg > test.m2v
mpeg2desc -a0 < test.mpg > test.mp2
mplex -f 8 -o test2.mpg test.m2v test.mp2

mplex complains.

If you run "tcprobe -i test.m2v", it reports the wrong size and 
framerate (NTSC instead of PAL).

Same problems with tcdemux/tcmplex.

>> When I try to demultiplex/multiplex them (I want to convert the audio
>> stream from mp2 to ac3), no multiplexer recognizes the video stream.
> This won't work with any tool I'm aware of (at least not reliably). 
> The problem is that once you demux them, you lose the timestamp info,
> so there is no way to remux them and keep a/v sync when done.  This is
> especially true if there are any issues with the input stream, or if
> you use the commercial-cut capability.  There is some code in
> mpeg2parse to create streams that can be demuxed cleanly, but it is a
> nasty problem, and I never got it working reliably.

Yes, I know about the sync problem. Fortunately, this has not been a 
problem for me in the past. ivtv recordings always have 79ms offset 
(according to avidemux) and I provide that offset to mplex when muxing 
them again after mp2->ac3. Even without that, I would not be able to 
tell (79ms is small enough for my ears).

The cut recordings from MythTV 0.19 have even a smaller offset. With one 
of those 3 that were OK, I demuxed, audio converted, requantized and 
remuxed without sync problems.

Thomas