On 8/16/05, gLaNDix (Jesse Kaufman) <[EMAIL PROTECTED]> wrote:
Depending on your tolerance for artifacts, sound quality, and a few other issues, DVD's can be reduced dramatically by using a more efficient codec. The recent threads on DVD languages contain discussion of this.
A full high quality DVD can run up to 8GB (That I've personally seen) due to using MPEG2, multiple audio tracks, subtitles, and very high bitrates. How much of that you want to retain is up to you, but most people are quite content bringing them down considerable.
Questions to ask yourself:
What parts of the movie are the most important to you? Do you need subtitles, multiple languages? Do you have a full multichannel stereo set up or are you willing to compress the audio? Are you extremely sensitive to audio distortion?
As an experiment to help you answer some of these questions, try this:
1) Test various audio settings, using mencoder to dump out part of the audio tracks: (Note: These assume you want the english track) (Note2: I'm taking a chunk a minute or two into the movie to give a representative sample, if you know there's a portion of sound you think you'd hear the difference on, use that instead)
Digital Quality AC3 audio:
mplayer MOVIE.vob -aid 128 -dumpaudio -dumpfile moviesound.ac3 -ss 200 -endpos 120
"Normal" audio 128 kbs:
mencoder -oac mp3lame -lameopts mode=2:cbr:br=128:vol=0 \
-ovc frameno -o frameno.avi MOVIE.vob -ss 200 -endpos 120
"Reduced" audio 96 kbs:
mencoder -oac mp3lame -lameopts mode=2:cbr:br=96:vol=0 \
-ovc frameno -o frameno.avi MOVIE.vob -ss 200 -endpos 120
Compare how they sound, and then compare the sizes, to get a rough estimate of the order of magnitude each size gives you.
After that, try converting the same portion of vob to the xvid codec at different bitrates, with 2 pass encoding. (Note, this command expects you to have one of those frameno.avi audio clips in the same directory)
I like to use this free tool to generate my mencoder command lines: http://f0rked.com/core/simplerip
--Ryan
Neil Davidson wrote:
> How are your DVDs stored? If they are as ISOs or the raw VOB/IFO files you
> could try ripping out unused audio tracks, subtitles etc.
what app do you use to rip out unused audio tracks, etc from just
straight VOB rips? no IFO files or anything, I just have the VOBS themself.
thanks,
-g-
Depending on your tolerance for artifacts, sound quality, and a few other issues, DVD's can be reduced dramatically by using a more efficient codec. The recent threads on DVD languages contain discussion of this.
A full high quality DVD can run up to 8GB (That I've personally seen) due to using MPEG2, multiple audio tracks, subtitles, and very high bitrates. How much of that you want to retain is up to you, but most people are quite content bringing them down considerable.
Questions to ask yourself:
What parts of the movie are the most important to you? Do you need subtitles, multiple languages? Do you have a full multichannel stereo set up or are you willing to compress the audio? Are you extremely sensitive to audio distortion?
As an experiment to help you answer some of these questions, try this:
1) Test various audio settings, using mencoder to dump out part of the audio tracks: (Note: These assume you want the english track) (Note2: I'm taking a chunk a minute or two into the movie to give a representative sample, if you know there's a portion of sound you think you'd hear the difference on, use that instead)
Digital Quality AC3 audio:
mplayer MOVIE.vob -aid 128 -dumpaudio -dumpfile moviesound.ac3 -ss 200 -endpos 120
"Normal" audio 128 kbs:
mencoder -oac mp3lame -lameopts mode=2:cbr:br=128:vol=0 \
-ovc frameno -o frameno.avi MOVIE.vob -ss 200 -endpos 120
"Reduced" audio 96 kbs:
mencoder -oac mp3lame -lameopts mode=2:cbr:br=96:vol=0 \
-ovc frameno -o frameno.avi MOVIE.vob -ss 200 -endpos 120
Compare how they sound, and then compare the sizes, to get a rough estimate of the order of magnitude each size gives you.
After that, try converting the same portion of vob to the xvid codec at different bitrates, with 2 pass encoding. (Note, this command expects you to have one of those frameno.avi audio clips in the same directory)
# video track (pass: 1, bitrate: XXX)Just put in different bitrates in the XXX spot each time. Be sure to delete the divx2pass.log file after each second run. The bitrate must match for each pass, however. A value of 800 for the bitrate will give you results around 700MB for a full DVD depending on your audio settings. Values around 1500 give bigger files, but are very nice looking.
nice -n 3 mencoder -sws 2 -oac copy -ovc lavc \
-lavcopts vcodec=mpeg4:vbitrate=XXX:vhq:vpass=1 \
-ffourcc XVID -ss 200 -endpos 120 MOVIE.vob -o /dev/null
# video track (pass: 2, bitrate: XXX)
nice -n 3 mencoder -sws 2 -oac copy -ovc lavc \
-lavcopts vcodec=mpeg4:vbitrate=XXX:vhq:vpass=2 \
-ffourcc XVID -ss 200 -endpos 120 MOVIE.vob -o "movie.avi"
I like to use this free tool to generate my mencoder command lines: http://f0rked.com/core/simplerip
--Ryan
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