[mythtv-users] [Improving] The Current State of Myth -> DVD

[Cory Papenfuss]

>> 1. Correct lossless MPEG2->MPEG2 cutting.  This one has not been
>> successfully done yet with any tools that I have found (mythtv or
>> otherwise).  Tools like GOPchop are close, but they're a little rough
>> around the cutpoints.
>
> With the short testing I've done, gopdit seems like a great solution
> to this problem.  But I saw that you mentioned in another thread that
> gopdit also has problems.  Can you say more about the problems you
> found?  The author of gopdit seems very responsive, so maybe the
> problems can be fixed?
>
> Dan

 	Check some of my previous posts on MPEG2 cutting.  Gopdit is (so 
far) the closest thing I've found to something that's useful.  A few 
potential issues remain:

- PTS/DTS... in order to make a correct edited stream with a chunk 
missing, all PTS/DTS after the first edit should be modified to reflect 
the cut.

- GOP-boundary.... does Mythtv use GOP boundaries, or can it do 
frame-accurate commercial tagging?  If the latter, then it'll have to be 
doctored to ensure gopdit is happy with it.

- Misc unknown "brokenness"... the result of a gopdit cut appears to play 
with mplayer, but it has reverse-seeking issues around a cut.  That's 
fishy.  Replex has issues with the stream while attempting to fix it:
Audio0  offset:  0:00:00.576  0:01:00.396
fixed video frame 1785
Wrong audio frame size: 864
fix audio frames 2482
<snip>
video DTS inconsistent:  0:04:00.431  0:04:00.431  0:03:00.878 
0:02:00.487 diff:  0:00:59.553
audio PTS inconsistent:  0:03:00.182  0:02:00.624 diff:  0:00:59.558
video PTS inconsistent:  0:04:00.465  0:04:00.465  0:03:00.911 
0:02:00.520  diff:  0:00:59.553
video PTS inconsistent:  0:04:00.498  0:04:00.498  0:03:00.945 
0:02:00.553  diff:  0:00:59.553

- Open/Closed GOPs... right now they're ignored.  Probably the easiest at 
this point to mark the thing "broken" (as is done) and move on.


-Cory


*************************************************************************
* Cory Papenfuss                                                        *
* Electrical Engineering candidate Ph.D. graduate student               *
* Virginia Polytechnic Institute and State University                   *
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