[mythtv-users] Re: More HD stuttering

Mudit Wahal mwahal at gmail.com
Thu Dec 1 21:30:16 EST 2005


Here is the mencoder script I use to transcode 1920x1080i mpeg2 to
1280x720p mpeg4. I use two passes and very high bit rate. I've 50"
Panny DLP connected to IOData LP2. When I play the original mpeg2 and
transcoded mpeg4, I can't tell any difference. All movies and shows
actually look better in mpeg4. Its very cpu intensive. One hour of
recording takes about 8 hours on my sempron 3000+. I usually cut the
commercials using commercial_cut program. That cut down 1hr of program
to 40-42 mins, and about 2 hrs of transcoding time.

##### no error checking is done #####

set oac="-oac copy" ## can substitute for mp3
set pp="pp=ci/hb/vb/dr/tn:1:2:3,"
set scale="1280:720:1" ## can change it to lower for non HD shows
set profile="dxnhdtv" ## change it to dxnhtntsc for 720x480 resolution or lower
set cartoon=":" ## set it to :cartoon: if you transcode kids cartoon
shows or simpsons
set oac="-oac copy"
set bitrate="9000" ## usually lower for non HD shows
set infile="$1" ## this is ur input file, 1st argument
set outfile="$2" ## this is ur output file, 2nd argument
set logfile="$infile".log

####### 1st pass #######
mencoder $oac -noaspect -vf ${pp}scale=${scale} -ovc xvid -xvidencopts
turbo${cartoon}pass=1:profile=${profile}:bitrate=${bitrate}:max_bframes=1:
-o /dev/null -passlogfile $logfile $infile

###### 2nd pass #########
mencoder $oac -noaspect -vf ${pp}scale=${scale} -ovc xvid -xvidencopts
pass=2${cartoon}profile=${profile}:bitrate=${bitrate}:max_bframes=1:
-o $outfile -passlogfile $logfile $infile


######## for 1280x720p recordings I use the following #####
set ofps="-ofps 30000/1001"
mencoder $oac -noaspect -vf pp=hb/vb/dr/tn:1:2:3 -ovc xvid
-xvidencopts turbo:pass=1:profile=${profile}:bitrate=${bitrate}:max_bframes=1:
-o /dev/null -passlogfile $logfile $infile $ofps
mencoder $oac -noaspect -vf pp=hb/vb/dr/tn:1:2:3 -ovc xvid
-xvidencopts pass=2:profile=${profile}:bitrate=${bitrate}:max_bframes=1:
$infile -o $outfile -passlogfile $logfile $infile $ofps

Hope it helps.

Thanks

Mudit


On 12/1/05, Jason Sharpe <mythtv.list at gmail.com> wrote:
> I agree, very VERY frustrating.
>
> I have built a couple of standalone front ends and both of them are
> stuttering (one worse then the other). SD plays back pretty well, however HD
> is a different story. Sometimes I can get decent performance however most of
> the time I want to jump out of the window.
>
> Specs:
>
> MSI 915G Mobo
> P4 3.0
> 1 Gig DDR400
> Nvidia 6600 GT PCIx
>
> I am also seeing combing, however from the previous comment I agree that it
> is probly showing 1080i content on in 720p. My guess is that is probly
> causing some other issues as well, not just combing, the front end has to
> scale down the picture to display it, I am sure that the processing power
> used to do that could improve playback.
>
> Since my theater and the plasma are only going to show 720p does anyone know
> of a good way  to set it up so myth looks at every show after recording
> finishes and automatically transcodes shows in 1080i to 720p? (user job
> perhaps?)
> I am new to myth (and Linux) so I haven't explored everything yet..:)
>
> I am looking forward to solving the problems, I can't WAIT to ditch my Tivo.
>
> Jason
>
>
> > ------------------------------
> >
> > Message: 8
> > Date: Thu, 1 Dec 2005 12:53:44 -0500
> > From: Jean Connelly < unksme at gmail.com>
> > Subject: Re: [mythtv-users] More HD stuttering
> > To: Discussion about mythtv <mythtv-users at mythtv.org>
> > Message-ID:
> >
> <fe95ddca0512010953h5866a678g664101fcd3dc5638 at mail.gmail.com>
> > Content-Type: text/plain; charset="iso-8859-1"
> >
> > Regarding:
> >
> >      The system is a 3.06 GHz P4 running Fedora Core 3.  The video Card
> > > is a NVidia 5200FX.  For capture, all I have is a HD3000.  I've checked
> > > that DMA is working on all the drives.  I built mythtv from stable
> > > source, 0.18.1.  I used the following configure options:
> > >
> > > --enable-xvmc --enable-opengl-vsync --enable-dvb
> > > --dvb-path=/lib/modules/2.6.12-1.1381_FC3smp/build/include
> > > --disable-firewire --disable-joystick --disable-ivtv --enable-proc-opt
> > > --disable-xvmc-vld --enable-opengl-vsync
> > >
> >
> > I have close to an identical system; and I have what is probably
> equivalent
> > stuttering.  HDTV (live or recorded) is totally unplayable in myth.  I
> have
> > tried with and without opengl sync.  I can't find the xvmc option in the
> gui
> > with this myth version to disable xvmc for testing.  Recorded 1080i plays
> > badly (with frequent pauses and never with audio sync) in mplayer with
> xvmc
> > and ffmpeg12mc and plays even worse without xvmc.  I'll try transcoding my
> > latest sample clips to see if they are fine when played back at standard
> > resolutions.
> >
> > I've got
> > 3.06 GHz P4 (which is a 533Mhz FSB chip)
> > 512 MB Ram
> > BE7-RAID mobo
> > Nvidia 5200FX
> > Fedora Core 3
> >
> > Night before last's myth svn.  No deinterlacing requested.
> > Prebuffer pauses all over the place.
> >
> > I think what we really need is an hdtv playback test suite external to
> myth
> > to get better benchmarks on actual system performance.  From previous
> posts
> > to the list ("well I got *my* P4 1.4Ghz system to playback hdtv") I think
> > that my system *should* be able to playback hdtv without issue, but
> perhaps
> > there are some motherboard weaknesses or such that make it impossible.
> >
> > Very frustrating.
> > Thanks!
> > Jean
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