[mythtv-users] Recomendations for Mpeg2 transcode settings?

[Barry Jett]

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

On some shows, like the new Battlestar, I needed to crop the black bands and
add the "-aspect 4/3" flag to the mythvideo settings. Shows went from 2.2 gig to
under 700 meg after compression and and commercial editing.

Barry