daniele rosa wrote: > no, it is smaller than the original VOB file I took for testing > steps: > - take a dvd video with some VOB files and I choose one of those > - run transcode to enc/rip video and audio (mpeg2enc,mp2enc) > - run mplex to create a final VOB from the just created mpeg2enc,mp2enc > files > - compare the obtained VOB with the starting one: the obtained one is > way smaller and the quality is worse > > > On 6/4/06, Phil Ehrens <[EMAIL PROTECTED]> wrote: > >daniele rosa wrote: > >> Hello, > >> I use > >> > >> transcode -i $line -y mpeg2enc,mp2enc -o $line.v -m $line.a -R 1 -w > >> 8000 -b 192 --export_prof dvd-ntsc -export_asr 3 > >> > >> where $line is my starting VOB file. > >> Then I use > >> > >> mplex -f 8 -V -v 1 -o $line.DAN $line.v.m2v $line.a.mpa > >> > >> and the resulting VOB is more or less a third in size than the one I > >> started from for my test. > >> How is that possible? quality loss? > >> The video I obtain doesn't look the same quality that the test one. > > > >Are you saying that after running mplex $line.DAN is smaller > >than the total size of $line.v.m2v and $line.a.mpa?
First, please avoid top-posting as it makes it difficult for other people to read the follow-ups. Top posting is reserved for people who can make final statements that are perfectly unassailable. Now, back to your problem. Re-encoding is not copying. Re-encoding involves decoding and recalculating the stream content. To be able to reencode material twice like you are doing and to retain near full quality requires considerable experience. It also requires two-pass video encoding whenever the video is transcoded. When I rip dvd content for archiving and later re-encoding to dvd format, I use an mpeg4 type codec for the video and simply copy the audio stream. I find that using a 2-pass encode to lavc's default codec (whatever it is, I don't have any idea) and targeting 2400 kbps I can get a rip that is almost as good as the original. When I re-encode that to a dvd it looks pretty darn good, and the final size is generally about 1/3 - 1/2 the size of the original dvd, and has an average bitrate of 2500 - 4000 kbps depending on the quality of the source. I suppose what I'm saying is that you need to do some experimenting and learn what works and what doesn't. There's no cookbook for video processing... It's still a black art in spite of the many excellent tools (like Transcode) that are available.
