[MPlayer-users] Re: Question on "trans-coding" with mencoder...

[Oliver Fromme]

Rainer Hantsch <rainer at hantsch.co.at> wrote:
 > A friend of me gave me some "svcd" files. These are unscaled mpeg-1 files with
 > a black bar on top and bottom, but mixed with mp3 audio.  Both, XINE and
 > MPLAYER are perfectly able to play these files.
 > Well, my problem is that I would like to make one big film out of the existing
 > two parts and store it in my prefered format, DivX4.

I've converted things to AVI/MPEG4 (a.k.a. "DivX") a lot,
and it works pretty well with mencoder.

The docs are certainly not optimal, but they're sufficient,
at least for the usual "standard" tasks.

 > [...]
 > Then I followed the instructions for concatenating multiple avi files to one
 > big file by entering exactly that what stands in the docs.

Did you try to concatenate the MPEG files first, and then
encode the result as a whole?  That should work.

 > I also tried to cut the first part's last 2MB because they are repeated at the
 > beginning of the 2nd part, using transcode's 'avisplit' (because nothing
 > similar seems to be possible with mplayer/mencoder).

Again, I would recommend you do the cutting on the source
MPEG, not on the resulting AVI file.  You can use the mpgtx
tool for that purpose.

Although, if the audio is layer-3, cutting is difficult.
That's because in layer-3 streams, the contents of frames
can partially depend on previous frames.  So you need a
pretty sophisticated tool to cut those without inserting
errors into the result and/or loosing sync.  I don't think
that mpgtx is smart enough for that.  Nor any other tool
that I'm aware of right now, I'm afraid.

 > · Can mencoder create mpeg files, too? (I have an original SuSE 8.0, which
 >   has a downstripped jpeglib, which cannot ENcode mpeg, only DEcode. When
 >   mencoder can do encoding without this library, shouldn't it work? - How?

No.  To the best of my knowledge, mencoder only supports
AVI as a "container" format.  Personally, I use mplayer +
yuvscale + mpeg2enc (+ sox + lame/toolame) to create MPEG
files from any source material (DVD, AVI, MOV, ...).

It's a bit tedious because several different tools are
involved, so I wrote a small script to make that task
easier.  Maybe it's helpful:
http://www.secnetix.de/~olli/scripts/dvd-to-vcd.tar.gz

(The name might imply it's only to convert DVDs to VCDs,
but that's not true anymore.  You can feed it almost
anything that mplayer is capable of reading, and it can
produce VCD, SVCD, or generic MPEG1 or MPEG2 streams.)

 > · Is there any video cutting tool planned, which allows to work with GUI
 >   and several file formats (DivX4, MPEG1/2,...)

Not that I'm aware of.  personally I prefer to do such
things with CLI tools, not GUI.  Because CLI tools are
much easier to automate, and easier to control, and the
actions are always exactly reproducible.

Having said that, there are tools which might come somewhat
close to what you're looking for, such as the video editor
which is part of the NuppelVideo tool set.  Disclaimer:
I haven't tried any of those GUI tools.

Regards
   Oliver

-- 
Oliver Fromme, secnetix GmbH & Co KG, Oettingenstr. 2, 80538 München
Any opinions expressed in this message may be personal to the author
and may not necessarily reflect the opinions of secnetix in any way.

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