[mythtv-users] Recomendations for Mpeg2 transcode settings?

[Brad Templeton]

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.