[mythtv-users] Keyframe identification in cutlist editor

Nick Rout nick.rout at gmail.com
Mon Feb 27 22:05:04 UTC 2012

On Thu, Feb 23, 2012 at 2:42 AM, Richard Morton
<richard.e.morton at gmail.com> wrote:
> I would suggest that in that case avidemux isn't handling it correctly...
> All the information is present to not cause artifacts when curing at non key
> frame locationsotherwise the tv could not render it.

My recollectionfrom using avidemux on mpeg2 material is that it would
only cut on keyframes. If you tried to cut elsewhere it would move to
a keyframe (can't remember whether it is back, forward or closest or
some other smarts). This may have changed in more recent versions.

dvbcut http://dvbcut.sf.net will cut to any frame and does so by
recontructing and re-encoding the frames from within the GOP so that
the new segment starts on a key frame.  dvbcut does not seem to have
received any development lately. There are indications on their
mailing list of a proposed new version covering h.264 etc but nothing
seems to have come to light.

In both cases the whole thing worked much better if run through projectx first.

To create a transcoded file in xvid or h.264 format my workflow was:

1. run through projectx to get rid of errors. if left in the errors
would result in audio sync problems. this would leave two demuxed
streams, video and audio.

2. import the video and audio into dvbcut

3. top/tail/remove adverts and export as mpeg2

4. import the mpeg2 to avidemux and process into the final product.

This is hardly automated though.

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