Transcoding in better quality
Yesterday we spent some time looking at transcoding under mythtv and how we can get better results.
We tried the following with their pros and cons listed underneath them.
mythtranscode
+ uses cut list
+ smaller file size but not by much.
- don't know how to run the profiles
- quality wasn't great
- no aspect ratio
nuvexport
- really crap quality
- wrong aspect ratio
- unsure of parameters
+ 1/3 the filesize
$ nuvexport
acidrip/mencoder
- no audio
+ small filesize
+ keeps aspect ratio
+ good quality
So we really wanted to get mencoder working as it seemed like the best. Someone also said to us that "nuvexport just calls mencoder/ffmpeg and mencoder and ffmpeg are both built on libavcodec, the same as mythtranscode so likely you just need to play with the settings more".
After playing with the settings for 4hours this was getting pretty frustrating.
To fix the no audio problem when encoding in mencoder we had to update mplayer to the latest SVN release. This is done by the following:
Make sure you install subversion first. (this is done through the Add/Remove programs in the menu or 'yum install subversion').
$ svn checkout svn://svn.mplayerhq.hu/mplayer/trunk mplayer
$ cd mplayer
$ ./configure
$ make
# make install
We finally found a command in mencoder which produces really good output:
Works, aspect, with sound, good quality, small size, with index and seeking.
$ mencoder /mnt/recordings/test.mpg -oac mp3lame -lame opts "abr:br=128" -ovc lavc -lavcopts "vcodec=mpeg4:vhq:v4mv:vqmin=2:vbitrate=1500" -vf "pp=de,crop=0:0:0:0,scale=480:-2" -o "/home/mythtv/outfile.avi"
However putting this into mythtv has yet to be done successfully. To enter these types of command you have to:
stop your backend
# service mythbackend stop
go into mythtvsetup -> general, hit next till you see user jobs, then enter the commands in there. You can setup different quality etc.
I've put this command in, even hardwiring the intput and output doesn't work! I've tried putting this into a simple script then calling that from mythtv, which doesn't work. There has to be something simple to fix this. I'm going to ask a few questions and get this working. At least now I can run it on the command line and compress some of my recorded shows so it will take much less space.
We tried the following with their pros and cons listed underneath them.
mythtranscode
+ uses cut list
+ smaller file size but not by much.
- don't know how to run the profiles
- quality wasn't great
- no aspect ratio
nuvexport
- really crap quality
- wrong aspect ratio
- unsure of parameters
+ 1/3 the filesize
$ nuvexport
acidrip/mencoder
- no audio
+ small filesize
+ keeps aspect ratio
+ good quality
So we really wanted to get mencoder working as it seemed like the best. Someone also said to us that "nuvexport just calls mencoder/ffmpeg and mencoder and ffmpeg are both built on libavcodec, the same as mythtranscode so likely you just need to play with the settings more".
After playing with the settings for 4hours this was getting pretty frustrating.
To fix the no audio problem when encoding in mencoder we had to update mplayer to the latest SVN release. This is done by the following:
Make sure you install subversion first. (this is done through the Add/Remove programs in the menu or 'yum install subversion').
$ svn checkout svn://svn.mplayerhq.hu/mplayer/trunk mplayer
$ cd mplayer
$ ./configure
$ make
# make install
We finally found a command in mencoder which produces really good output:
Works, aspect, with sound, good quality, small size, with index and seeking.
$ mencoder /mnt/recordings/test.mpg -oac mp3lame -lame opts "abr:br=128" -ovc lavc -lavcopts "vcodec=mpeg4:vhq:v4mv:vqmin=2:vbitrate=1500" -vf "pp=de,crop=0:0:0:0,scale=480:-2" -o "/home/mythtv/outfile.avi"
However putting this into mythtv has yet to be done successfully. To enter these types of command you have to:
stop your backend
# service mythbackend stop
go into mythtvsetup -> general, hit next till you see user jobs, then enter the commands in there. You can setup different quality etc.
I've put this command in, even hardwiring the intput and output doesn't work! I've tried putting this into a simple script then calling that from mythtv, which doesn't work. There has to be something simple to fix this. I'm going to ask a few questions and get this working. At least now I can run it on the command line and compress some of my recorded shows so it will take much less space.
posted by Mick at 2:50 PM
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