On Sun, 19 Nov 2006, Delio Pereira Guimaraes wrote:

> >     Do the audio and video remain in sync?...
> 
> No, they are in sync. If there's some difference, it's only about a quarter of
> a second or less. Only the movie length is shortened.

        Ok - and I begin to form a theory about what is happening.

> Sure, I use an almost silent pentium 233mmx running a ltsp terminal to a 
> server that is an Athlon 800 with 512MB of memory. I run kmail, firefox and 

        And I thought 1GB was small :)

> I think there's no problem with the DV file.

        I agree.

> Panasonic PV330 (VHS camcorder)
> Sony TRV340 (Hi8 DV camcorder)

        I think that's what is called a "Digital8" camcorder. I had a similar
        unit and it used Hi8 tapes but recorded DV format data.

> The DV file is complete! It occupies about 14G in the harddisk.
> I disconnect everything and then I convert it to mpeg.

        12GB/hr for DV.  If you're using AVI or 'dv2' instead of 'raw' then
        the overhead is quite a bit higher and 14GB or so per hour would be
        correct.

> Now it generated file nat.mpeg, see size comparison with first natal_old.mpg 
> file with lots of parameters and second file natal.mpg with the suggested 
> parameters.
> ==========================================================
> [EMAIL PROTECTED] ~]$ ls -lrt nat*.mp*g
> -rw-rw-r--  1 delio delio 2474954752 Nov  4 23:56 natal_old.mpg
> -rw-rw-r--  1 delio delio 3488636928 Nov  5 05:49 natal_caluje_old.mpg
> -rw-rw-r--  1 delio delio 2527358976 Nov 18 17:48 natal.mpg
> -rw-rw-r--  1 delio delio 3547518976 Nov 18 23:34 natal_caluje.mpg
> -rw-rw-r--  1 delio delio 1576384512 Nov 19 14:52 nat.mpeg

        Those look reasonable to me.  Slight variation but that is expected.

> And xine showed a length of about 20 minutes!

        But how long does Xine need to play the file?

        "show a length" is not reliable for variable bitrate files!   

        I think xine is dividing the file length by the the bitrate in 
        the MPEG-2 header and using that as the duration of the movie.  But
        that calculation assumes a 'constant bitrate' and does not work
        with variable bitrate files.
        
> I'm now converting the file to a DV type2 using kino. I'll encode that file 

        I always use 'raw'.  Less overhead (does not have a 2nd copy of the
        audio data in the file) and, a little less disc space.  Also with 'raw'
        you can do emergency or quick edits using dd" (raw DV has a frame 
        size of 120000 bytes/frame for NTSC, 144000 for PAL)

        If the DV file is OK and if mpeg2enc has no bugs then I would not
        worry about the estimated times that xine is printing out.

        Cheers,
        Steven Schultz


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