transcoding mpeg2 -> mpeg2 (was: RE: [mythtv] DVB,
(new) recording profiles, and transcoding)
Edward.Wildgoose at FRMHedge.com
Fri Oct 3 17:50:42 EDT 2003
Geoff. How frequent are key frames in mpeg2? (I know I could look for myself, but I'm not near a suitable PC at the moment)
If they are pretty frequent then personally for the "non-re-encode" option I would be very happy if it just jumped to keyframes. Probably you don't need to clip to keyframes though for the cut out, only the cut in again?
By keyframes I had assumed you meant GOP I-frames? I was under the impression you didn't have these at regular intervals anyway, and could insert one for scene changes anyway?
Hmm, sounds very complicated anyway. I have a quick look at avidemux, but it says that it only does frameexact for mpeg4 (at least if there are backward referencing P-frames.)
I did also find a reference to: http://gopchop.sourceforge.net/ which seems to do what we want (I haven't tested, just seen the website).
If I had a choice then I would envisage using transcode in one of two ways, a) either transcoding to mpeg4, possibly at a different resolution. or b) not re-encoding, but just chopping commercials (I would have assumed that re-encoding to mpeg2 would only be for making svcd's and then a different and more manual interface would be appropriate)
Perhaps an appropriate interface would be to pop up a box with: "cut", or "re-encode" option when the user presses the "x" key?
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