Re: [transcode-users] Adjusting Volume for a VOB

[Christoph Neumann <neumann@xxxxxxxxxxxxxxxxxxxx>]

Erik Slagter wrote:
> On Tue, 2005-08-30 at 18:21 -0700, Christoph Neumann wrote:
>
> > I'm trying to amplify volume for an audio track in a VOB file.  I'm 
> > having problems.  Unfortunately I cannot reencode to VOB from another 
> > source.  The VOB file is all I have.
>[ ... ]
>
>All of this has been discussed lately.

Are you referring to the "How do I rip a DVD to separate m2v and m2a 
files" thread?  If so, it isn't what I'm looking for.  Maybe I need to 
explain myself some more.  I don't have a VOB file from a commercial 
DVD, I have a MPG file encoded according to the VOB standards that I can 
use with dvdauthor to make a DVD.  (I made this VOB previously and I no 
longer have the source.)

First item I didn't see discussed: The following process, which simply 
tries to split the VOB MPG file and put it back together again results 
in sync errors.  Why can't I, at the very least, take an mpg file, split 
it and mplex it and have it work?  What am I missing?

tcextract -i infile.mpg -x mpeg2 > test.m2v
transcode -i infile.mpg -x null -o test -y null,ac3 -N 0x2000 -E 48000 
-b 384
mplex -f 8 -o test.mpg test.m2v test.ac3

Second item that I didn't see discussed: Why is the frame rate detected 
differently between transcode and ffmpeg?  Might this be affecting the 
first problem?

[tcprobe] MPEG program stream (PS)
[tcprobe] summary for infile.mpg, (*) = not default, 0 = not detected
import frame size: -g 720x480 [720x576] (*)
     aspect ratio: 4:3 (*)
       frame rate: -f 23.976 [25.000] frc=1 (*)
                   PTS=0.5000, frame_time=41 ms, bitrate=104857 kbps
      audio track: -a 0 [0] -e 48000,16,2 [48000,16,2] -n 0x2000 [0x2000]
                   PTS=0.5000, bitrate=384 kbps
                   -D 0 --av_fine_ms 0 (frames & ms) [0] [0]

This is from ffmpeg (note the frame rate doesn't match tcprobe)
Input #0, mpeg, from 'infile.mpg':
  Duration: 01:27:06.1, start: 0.500000, bitrate: 1881 kb/s
  Stream #0.0: Video: mpeg2video, 720x480, 29.97 fps
  Stream #0.1: Audio: ac3, 48000 Hz, stereo, 384 kb/s


- Christoph