[mythtv] MPEG2-MPEG2 transcoding: Illegal video stream

Geoffrey Hausheer mythtv0368 at phracturedblue.com
Thu Mar 2 11:00:35 UTC 2006

On 3/2/06, Thomas Börkel
> I can also provide the first 10 MB of the original file, if necessary.
Sorry I wasn't clear.  Yes, I need the 1st 10MB of the original, not the output.

> 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.
The transcoder will start the offset at less than 1 frame (so the
initial offset should be < ~40ms depending on the
frame-rate/audio-rate).  However, each time you do a commerical
change, you can increase your offset by as much as two audio frames
(so you could be skewing the audio by 80ms per cutpoint).  In
practice, it won't be that bad, but something to be aware of.  One of
the reasons for the mpeg2<->mpeg2 transcoder in myth is that it
actually pays attention to PTS values, and so doesn't muck up the A/V
sync during processing (or at least it shouldn't)

For you to use these streams to burn to DVD, you need to specify the
'--ostream dvd' flag, as ths will create NAV packets, which should
make it DVD compliant.  There really should be a line in the trancoder
setup that lets you specify options like this, on a per-profile basis.

By the way, why would you convert mp2 to ac3?  You will incur a
generational loss, and PAL DVD allows for mp2 as the only audio stream
on the disc (NTSC doesn't, but in practice, I've never seen a DVD
player that didn't support it)

I'll take a look at the issues you reported once you provide me with
the original tream though.


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