[mythtv-users] Lossless MPEG2 cutting, revisited

[Josh Burks]

I, too, have been thinking about this lately. I looked at the GOPchop
code, trying to find out how to just cut specified frames out of a
recording. I believe GOPchop uses libmpeg2, so I looked into that,
just to find that libmpeg2 has no documentation.

I've got my Recording-To-Dvd process down to 2 steps now, thanks to
nuvexport and the mpeg2cut script, but I don't like how avidemux2 is a
GUI and requires X.

Basically, what I want is a program that works just like the mpeg2cut
script (e.g. mpeg2cut infile outfile range_of_frames_to_keep) that is
command line only.

Heck, if we could get that working, a "MythArchive" module would be
very feasible (to me anyways.)

Just my .02 cents....

Josh


On Fri, 14 Jan 2005 08:54:34 -0500 (EST), Cory Papenfuss
<papenfuss at juneau.me.vt.edu> wrote:
>         It's been awhile since this has been discussed, but I'm wondering
> if there's any status on this front.  I just happened to look and see if
> GOPchop had been updated since last time I used it, but it appears to have
> died on the vine.  It seems to have some issues, but it does have a nice
> .cpp skeleton for parsing and clipping MPEG2 files at GOP boundaries.
> I-frame clips would probably be adequate, but since they are still lossy
> with missing P-frames, perhaps a transcode of a few frames around
> cutpoints would suffice?
> 
>         I'm just offering food for thought for those more in the code.
> Just for the record, however, the ivtv driver appears to always output the
> same GOP length/format (15 frames/GOP IIRC).  With a 2-pass reencode to
> mpeg2 (e.g. with avidemux), I get varying-length GOPs.  It's got potential
> for better quality/bitrate than archiving to DVD right off the ivtv
> card... might be a worthwhile option for any sort of "MythArchive" module
> or something.
> 
> -Cory
> 
> 
> *************************************************************************
> * Cory Papenfuss                                                        *
> * Electrical Engineering candidate Ph.D. graduate student               *
> * Virginia Polytechnic Institute and State University                   *
> *************************************************************************
> 
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