[mythtv-users] Cutting HD-PVR recordings

Marius Schrecker marius at schrecker.org
Sat Dec 12 10:25:15 UTC 2009

 On Fri Dec 11 19:03 , Christopher Meredith <chmeredith at gmail.com> wrote:On Fri, Dec 11, 2009 at 9:43 AM, Marius Schrecker <marius at schrecker.org> wrote:
>>On Fri Dec 11 15:31 , Doug Vaughan <r.d.vaughan at rogers.com> wrote:For HDPVR recordings I use Avidemux to manually perform lossless edits.
>>The restriction is that I must force my STB to only output at 720p. You
>>must save the edited file in an avi container and then use ffmpeg to
>>copy file avi into a mkv and add a seek table. The audio sync and
>>general quality has been excellant. On the rare occassion that there is
>>an audio seek issue, I use mkvmerge_gui to resync the audio.
>>To make this experience easier I created a Nautilus script that combines
>>starting Avidemux and creating the mkv file with ffmpeg after you exit
>>I also use a compiled version of Avidemux as my distro's package seems
>>to lack some options (Ubuntu 9.10).
>>One other thing I should mention is that before editing I have a userjob
>>to rename the recording and copy it to a physically separate hard drive.
>>Editing and recording at the same time cause disk thrashing which will
>>cause issues if you are recording at the same time. You can use rsync
>>with bandwidth option (--bwlimit) in the userjob to control the disk
>>thrashing during the copy and rename process.
>>Although this article is out of date the section on Avidemux and the
>>HDPVR is correct.
> Thanks Doug,
>  Especially for the tips about compiling avidemux, and the disk thrashing issue. I have some spare disk space on a separate drive that I didn't know what to do with, now it seems it might be useful after-all ;-)

I cobbled together a script that does this using avidemux2_cli and
which can be run as a user job. You can read more about it here:


It usually works pretty well for me, but I have been noticing that I
get sync problems on recordings where the HDPVR hiccups during
recording. The resulting file starts out in sync then jumps out at the
hiccup point. I'm not sure how this can be addressed (if at all).

Thanks Christopher and Bob,

How does you script handle cut points Christopher? Does it cut to a specific frame, or is it a limitation of avidemux that we can only cut to keyframes? I don't suppose there's any way of editing in extra keyframes around a commercial break??


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