Re: Video editing: impossible without transcoding? (was: Video editing)

[Rodolfo Medina <rodolfo.medina@gmail.com>]

Rodolfo Medina <rodolfo.medina@gmail.com> writes:

>>>>> I want to divide a video file into two pieces, or, more in general, cut
>>>>> off and select pieces of a video file.
>
> [...]
>
> I need also to append two video
> files one another.  What I'm trying to do is to select pieces from a dvd.


I've been trying different tools.  The most powerful seems to me ffmpeg.  But
it also, like others, needs transcoding your video file, i.e. decoding it and
encoding it again, with loss of quality.

The only program that avoids that seems to be gopchop, only for cuttting the
video file into chops.  It doesn't seem to do anything else than this.

Does anyone have experience of video editing without transcoding?

In particular, what I want is to join two video files.  *If* they come from the
same DVD, old plain `cat' command joins them fine:

 $ cat file1.mpg file2.mpg > total-file.mpg

, otherwise there are troubles.

Since the first one is just an image, I want to encode it using ffmpeg so to
make it most similar to the second and then `cat' them together.  But I don't
find the proper ffmpeg magic formula to do that.  The properties of file2.mpg
are:

Input #0, mpeg, from 'vts_01_2.vob':
  Duration: N/A, start: 556.163678, bitrate: N/A
    Stream #0.0[0x1e0]: Video: mpeg2video, yuv420p, 720x576 [PAR 16:15 DAR 4:3], 8000 kb/s, 25.00 tb(r)
    Stream #0.1[0xa0]: Audio: pcm_s16be, 48000 Hz, stereo, s16, 1536 kb/s

, so I tried with file1 with:

 $ ffmpeg -i file1.mpg -target pal-dvd -acodec pcm_s16be -b 8000k -s 720x576 -ab 1536k -ac 2 -r 25 -f mp2 test.mpg

, without success when `cat'ting it to file2.  Hints welcome.

Thanks
Rodolfo