[mythtv-users] Recomendations for Mpeg2 transcode settings?

[Andrew Close]

On 4/25/05, Brad Templeton <brad+myth at templetons.com> wrote:
> On Mon, Apr 25, 2005 at 11:41:15AM -0500, Barry Jett wrote:
> > On 4/23/05, William <wmunson at rochester.rr.com> wrote:
> > > Hello List,
> > >
> > > I would like to transcode down some mpeg2 (pvr-250) recordings into (mpeg4,
> > > avi, divx, whatever...) to keep as videos for when people come over. This is
> > > primarily for kids stuff but I would like to keep some adult titles too.
> > > Here is my question.
> > >
> > > What is the best format and settings to give a good reduction in file size
> > > without noticably reducing the quality of the picture? Please note that I am
> > > viewing on a hi-def widescreen monitor so good picture quality is vital. The
> > > format does not need to be directly supported by transcode but it needs to
> > > be playable with mplayer or xine. Avidemux2 comes to mind as an alternative
> > > for doing the conversions.
> > >
> > > I tried transcoding using the default mpeg4 settings in myth but the results
> > > were very poor. Very blocky and lots of artifacts. Maybe acceptable for kids
> > > but not personnaly. Any thoughts?
> > >
> > > Bill
> > >
> > >
> >
> > After much experimentation, I used the following with good results for
> > compressing
> > PVR-250 mpeg2's to mpeg4. While slower on encoding , the msmpeg4v2 codec
> > leaves me with a file easily playable on windows, and the quality seem's a tad
> > better. I usually play the files with mythvideo on my high def Sony.
> >
> > TARGET="source.nuv"
> > OUTPUT="/data/video/new-file.avi"
> >
> > #optimal bitrate is 5.86*width*height
> >
> > OPTIONS="vbitrate=3000000:mbd=2:keyint=132:vqblur=1.0:cmp=2:subcmp=2:dia=2:mv0:last_pred=3"
> >
> > rm -f frameno.avi
> >
> > nice -n 19 mencoder $TARGET -vop denoise3d,lavcdeint \
> > -ovc lavc -lavcopts vcodec=msmpeg4v2:$OPTIONS:vpass=1 \
> > -oac mp3lame -lameopts cbr:br=128 \
> > -o $OUTPUT
> >
> > nice -n 19 mencoder $TARGET -vop denoise3d,lavcdeint \
> > -ovc lavc -lavcopts vcodec=msmpeg4v2:$OPTIONS:vpass=2 \
> > -oac mp3lame -lameopts cbr:br=128 \
> > -o $OUTPUT
> 
> It makes sense to use vpass=1:turbo instead of vpass=1 in this case.
> 
> In fact, I just do:
> 
> for pass in 1:turbo 2 ; do
>     mplayer command $pass:$options
>     done
> 
> To simplify and help editing it.

are these options you enter in during Mythtv setup?  or are they
cmd-line options for transcode?  or homegrown scripts?
any other docs you could point me to?
thanks