[mythtv-users] MPEG4 bigger than MPEG2?

[Ross Boylan]

On Fri, 2012-03-09 at 09:06 -0700, Tom Hayward wrote:
> On Thu, Mar 8, 2012 at 20:51, Ross Boylan <RossBoylan at stanfordalumni.org> wrote:
> > Hi, everyone.  I'm a new user, and am wondering why transcoding is
> > making my files bigger.  More specifically, I think I have transcoded a
> > file from MPEG-2 to MPEG-4, and it got a little bigger (3.1 vs 2.9GB).
> 
> The real question is: Why do you want to transcode? 
To save space.
> Most HDHomeRun
> users don't bother with transcoding. I know I prefer to watch my
> recordings in original quality. I only transcode to H.264/MPEG-4 AVC
> if I plan to keep a recording forever. I usually let recordings
> auto-expire after watching them, so a CPU-intensive MPEG-2 to MPEG-4
> transcode is pointless.
> 
> With a lossless MPEG2 transcode, you can save some storage without
> loss in quality (and it's fast, too). Re-muxing from MPEG2-TS to
> MPEG2-PS can save up to 20%. Cutting the commercials usually saves 30%
> (assuming 30% of the recording was commercials). These are features of
> the mythtranscode utility: http://www.mythtv.org/wiki/Mythtranscode
How do I accomplish that from the frontend?  More specifically....

When editing the transcode options (autodetect MPEG2) does selecting
"lossless transcoding" do the TS->PS transcode?  The description, e.g.,
"keep audio and video formats identical to the source", sounds as if it
will not.  If it does not, how do I get the desired conversion?  The
only video codes I see are MPEG-4 and RTJpeg.

What controls whether commercials are deleted from the transcoded
recording?

Finally, is it possible to set the options for a single recording?  I
believe that X will schedule a transcoding for one recording, but the
options settings seem to bring me to the schedule.  E.g., in "Watch
Recordings" I highlight a recording and press M.  "Job options" doesn't
seem to have an option to alter the setting, and "Recording Options"
appears to take me to the options for the schedule (recording rule).

Thanks.
Ross