[mythtv] New MPEG2 commercial-cut code ready for testing

Stuart Auchterlonie stuarta at squashedfrog.net
Sun Nov 13 17:37:41 EST 2005


On Sun, Nov 13, 2005 at 01:53:05PM -0800, Geoffrey Hausheer wrote:
> On 11/13/05, Stuart Auchterlonie wrote:
> > On Sun, Nov 13, 2005 at 09:15:49AM -0800, Geoffrey Hausheer wrote:
> > >
> > > if it doesn't work, I'll need a gdb backtrace.
> > >
> >
> > I've just gone straight for the backtrace.
> > It looks like there is an invalid AVFormatContext being
> > passed in, so when it attempts to use it things fall apart.
> >
> This should be fixed in 0.8

Yep it's fixed. This version runs to completion.
Just testing the output with mplayer. Looking good so far.

> 
> > I'm volunteering for extensive testing of this tool as I want
> > to be able to get to a point where I do an MPEG - MPEG
> > transcode to dump all commercials, then convert the result
> > to a DVD compliant stream.
> As I've said in the previous thread, this may not be so easy.  If you
> start with a DVD compliant stream, it should work pretty well, but
> depending on your locale, it can be pretty difficult to get a good
> starting place.  For instance:  In the US, the DVD spec requires that
> you have either an AC3 or PCM stream, with an MP2 stream being an
> optional additional stream.  As far as I know everywhere else in the
> world, it is the opposite (MP2 or PCM are required, AC3 is optional). 
> I am not sure what the constraints on GOP structures are yet (since
> this code doesn't insert them except after a cut-point, you need to
> ensure the structure of the stream is correct to start with).  And it
> seem sto all come down to compliance.  I have spent a lot of time
> trying to generate multiple-player compliant DVDs, and found it to be
> quite tricky.  Many players are picky about the AC3 thing above
> (though many aren't), some don't like encdings from liba52 (or
> bbmpeg), but work ok with commercial encoders, I normally need ot
> reencode to meet the resolution requirements which gets me the correct
> GOP structure for free, but haven't had much luck copying directly
> from a PVR250 output to DVD.  I guess it all depends on what works for
> you.
> 
> But I'll be happy to try to fix things as long as I can get good debugging data.
> 

My main requirement is to remove the flagged sections of the
data stream, without changing it otherwise. It looks like your
test tool does the trick.

I have a good starting point. I'm starting with an MPEG TS stream
recorded from DVB-T. Here's the relevant part of the output

----
Opening /data/mythtv/1014_20051017222900.mpg
Input #0, mpegts, from '/data/mythtv/1014_20051017222900.mpg':
  Duration: N/A, bitrate: N/A
  Stream #0.0[0x23a], 25.00 fps: Video: mpeg2video, yuv420p, 544x576, 10000 kb/s  Stream #0.1[0x23b](eng): Audio: mp2, 48000 Hz, stereo, 192 kb/s
  Stream #0.2[0x23c](eng): Audio: mp2, 48000 Hz, mono, 64 kb/s
  Stream #0.3[0x23d](eng): Subtitle: dvbsub
Skipping unsupported codec 3
#0 PTS:3307559283 Delta: 0.000000ms queue: 12
#1 PTS:3307558334 Delta: 10.544444ms queue: 2
#2 PTS:3307557608 Delta: 18.611111ms queue: 3



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