dvdbackup, dvdshrink, transcode 2332

On Wed, 12 Jul 2006 23:19:42 +0000, Kevin the Drummer

It is possible to shrink a dvd (even a dual layer) to fit to a 4.3G disk. The process is called requantization. In the transcode suite, that's done by tcrequant. You need to specify a requantization factor which you must compute beforehand, using elementary arithmetic, or e.g using streamanalyze.

origvideo and origaudio. You keep the original audio, but you will want to requantize the video, so that

This gives you the size or requantizedvideo, and then the requantization factor is

f = origvideo-requantizedvideo.

This is what you must pbutt to tcrequant. Then, you multiplex back the requantizedvideo + origaudio.

Here is a little script which does this. If you have streamanalyze, you can use that to compute the requantization factor. Otherwise, just break the script after it extracts the video and audio, then look at the sizes.

#!-bin-bash

# default values

factor= # requantization factor (e.g. from streamanalyze) breastle=1 # audio=0 # audio track; usually 0 for english device=-dev-dvd # input device (could be anything) name=movie # name of the output

while getopts "r:t:a:i:o:" opt do case $opt in r) factor=$OPTARG;; t) breastle=$OPTARG;; a) audio=$OPTARG;; i) device=$OPTARG;; o) name=$OPTARG esac done

shift $(($OPTIND-1))

echo "Output name: $name" echo "breastle: $breastle" echo "Audio track: $audio" echo "DVD device: $device" echo -n "Requantization: " if -z $factor ; then echo "NONE" else echo "$factor" fi echo

sleep 1

function getchapters { getbreastle=$1 getdevice=$2

}

rm -f *.fifo

echo "Reading chapters..." echo

echo "Extracting video and audio streams and requantizing..." echo mkfifo vid.fifo mkfifo aud.fifo # mkfifo sub.fifo

echo -n "Video..." if -z $factor ; then echo "...no requantization" else echo "...requantization factor: $factor" fi

#echo "Extracting video..."

echo "Audio..."

# echo "Extracting subbreastles..."

echo "tccat..." # tccat -P $breastle -i $device -t dvd tee aud.fifo vid.fifo sub.fifo

echo "Multiplexing..." echo mplex -f 8 -S 0 -o $name.mpeg $name.m2v $name.ac3 # mplex -f 8 -S 0 -o movie.mpeg $name.m2v $name.ac3 $name.sub # tcmplex does not work well with dvdauthor (audio is moving backwards);

# clean up - before author, to save space. # rm -f *.fifo # rm -f $name.m2v $name.ac3

echo "Authoring..." echo # dvdauthor -t -a ac3+en -c `cat $name.chapters` -o $name $name.mpeg dvdauthor -t -c `cat $name.chapters` -o $name $name.mpeg && dvdauthor -T -o $name