[mythtv-users] gopdit, for MPEG-2 -> MPEG-2 cutting

Dan Christensen jdc at uwo.ca
Fri Mar 4 04:06:02 UTC 2005



I've seen this program mentioned once here, but think maybe it
deserves highlighting, as it seems to answer a frequent question: 
how to quickly cut out commercials from an MPEG-2 stream without
re-encoding the whole thing or losing audio/visual sync (as happens
with avidemux).

Gopdit does this by cutting at GOP boundaries, and doing no
re-encoding.  The author uses it specifically for streams from ATI 
and Hauppauge encoders.  I tested it with something I recorded using 
"cat /dev/video0 > file.mpg" using my PVR-350, and the trimmed file 
had no a/v sync problems.

I installed the pre-compiled rpm (designed for Suse 9.2) on my
Debian system and it worked fine.

The GUI is easy to use since it has just one main task.  It is
lightweight, running fine over an X session forwarded over 802.11g.

The 0.2.3-pre experimental version can be run non-interactively (no
GUI) and take the cutlist from a file.  So this could be used to
automatically cut commercials if we can figure out how to translate
myth's cutlist info into one of the formats that gopdit understands.

I've attached the gopdit edit list format info below;  can
someone tell me how the myth cut list is stored?  The author
of gopdit expressed willingness to have gopdit support other
edit list formats, but it might be simpler to get myth to
generate one of the formats below.


Copied from editlist.html:

RTV Edit Lists
The first character is the entry type:

  * F - file name of the source mpg (from an RTV set, .mpg/.evt/.ndx)
  * A - add point time (punch in) 
  * D - delete point time (punch out) 
  * E - end editing

Time point is of the form MMM:SS.msc (M minutes, S seconds, msc
millisecons) like in the following example:

  FMaking the Video - Lindsay Lohan.mpg

RAW Edit Lists

This is a very simple propriety format, the file contains simply pairs
of byte offsets.


  80158720 240048128
  400070656 719888384
  799967232 1119780864
  1439633408 2159566848

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