[mythtv-users] Compressing PVR-x50 SD video using Handbrake---any advice?

f-myth-users at media.mit.edu f-myth-users at media.mit.edu
Wed May 1 07:29:09 UTC 2013


If anyone has a known-working toolchain for compressing SD video
from PVR-x50 devices using Handbrake, I'd love to know about it.
I'm basically trying to turn MPEG-2 into H.264 of any flavor.

I recently had occasion to try this, discovered it failed badly, and
the top hit of the first search I did turned up [1]--which turns out
to be -my own question- about how to do this from 2.5 years ago.  That
thread sorta petered out, and even with a release that's several years
later by now, my attempts just now have failed to find a working
toolchain that would accomplish this, despite the fact that it seems
simple.  Using Handbrake directly got zillions of errors and produced
a tiny file that mplayer couldn't swallow; using ProjectX to
preprocess and demux left me with files that I wasn't sure how to
remux correctly, given that ffmpeg's args seem to change every other
week and that it's now being deprecated in place of avconv.  Maybe I
just haven't been persistent enough in figuring out the ffmpeg/avconv
args and that's all I need.

[One rather alarming feature of this process is that the two resulting
streams claim to differ in duration by about 15 minutes on a 2.5-hour
test file I tried.  Yet the original plays perfectly fine as MPEG-2
and does not have any sync problems.  When I noticed the mismatch in
durations, I decided I was probably doing it wrong---and both ffmpeg
and avconv simply -hung- at some point during the remux, burning 100%
CPU but not making the output file any larger after several minutes
in this state.  So rather than trying to debug my existing process,
maybe it's better to see if someone has an already-working one.
Note that the source material for my test was a cable box producing
S-Video, so it's very unlikely that there's any significant corruption
in the input signal; certainly nothing observable just by watching it.]

For the sake of argument, I'm trying to do this at the moment under
Ubuntu 12.04, and I'm doing it on isolated recordings---not something
I'm trying to get Myth to understand post-compression.  (Though any
advice on that would be perfectly welcome, too---I presume it's
basically run it as a transcode job and if necessary rebuild the
seektable---but I first need to get something that isn't garbage,
and some of these want to happen with files Myth has never seen.)

Thanks!

[1] http://www.mythtv.org/pipermail/mythtv-users/2010-November/303827.html


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