[mythtv-users] Video Editing HELP! (COMPLETE noobie)

Nick Rout nick.rout at gmail.com
Thu Jun 4 00:21:54 UTC 2009

On Thu, Jun 4, 2009 at 11:11 AM, belcampo <belcampo at zonnet.nl> wrote:
> Nick Rout wrote:
>> On Thu, Jun 4, 2009 at 12:40 AM, barbex <barbex at gmail.com> wrote:
>>>> So I loaded avidemux last night and gave IT a shot.  "Better" is a
>>>> phrase
>>>> that comes to mind, at least it's easy enough to use.  Getting rid of
>>>> commercials was pretty easy after indexing, and saving instead of a 12 -
>>>> 15
>>>> hour process was about 30 minutes...
>>>> That's about as best as I can say.  The video STILL doesn't work, it now
>>>> looks like it's playing on x2 and there's still no sound.  I've tried
>>>> AVI
>>>> and mpeg video saving routines, all a no go.
>>> I was going to suggest avidemux as the only program I could find that
>>> made any sense to me. And I have successfully cut videos from mpeg
>>> files that mythtv recorded into new mpeg files. I remember that I had
>>> to pay attention to Transport Stream (TS) versus PS whatever stream
>>> and it failed on some files because of errors in the recording. There
>>> is some information here:
>>> http://avidemux.org/admWiki/index.php?title=Editing_MPEG_capture_(DVB_or_IVTV)
>>> about that problem. So far nuv-files have stumped me but only because
>>> I got scared of ProjectX.
>>> ProjectX seems to be the solution to all and everything when it comes
>>> to video and repairing them. I am by no means an expert in this but I
>>> would try that next.
>> I find dvbcut http://dvbcut.sourceforge.net/ to be very good at
>> cutting DVB material frame accurate before encoding with avidemux.
> Where can I read "frame accurate" cutting ?

Most editors only cut to the nearest I frame, and doesn't have to
re-encode anything (as each GOP is maintained).

DVBCUT is frame accurate and re-encodes enough to make new I-frames at
the beginning of the new GOP.

Say you have a sequence of frames that you want to cut out the first
three frames.

I B B x P B B P

Normally you can't do that because the remaining sequence PBBP does
not start with an I-frame, the P frame needs the frames before it to
be decoded.

So dvbcut re-encodes the remaining sequence to create a new GOP
starting with an I-frame.

Hence on the web page: "It follows a "keyhole surgery" approach where
the input video and audio data is mostly kept unchanged, and only very
few frames at the beginning and/or end of the selected range are
re-encoded in order to obtain a valid MPEG file."

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