[mythtv-users] Lossless MPEG2 cutting, revisited

Cory Papenfuss papenfuss at juneau.me.vt.edu
Fri Jan 14 08:54:34 EST 2005


 	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 			*
*************************************************************************



More information about the mythtv-users mailing list