KEYWORDS MPEG-1, MPG, video, edit, VirtualDub,
mpgtx, avi, vcd, video CD, Pinnacle, PCTV This article describes how to edit mpeg-1 files using VirtualDub, mpgtx
and a small perl script to automate the process. ABSTRACT I started to seek some tool that is capable splitting and joining
mpeg-1 files. I have found mpgtx and started to use it together with
VirtualDub. I used VirtualDub to see where the advertisements start and end
and then I created the command line to join the parts of the film without the
advertisements. This was cumbersome. I realized that I can automate the
process with some perl script. HOW IT WORKS
When you edit a film with VirtualDub it does not perform the actual
editing functions as you do. It only stores the actions and then it executes
them when you save the file. There is also a possibility to save only the actions
and then perform the actual saving in a batch. This creates a text file that
describes all the editing functions you performed. VirtualDub calls this file
the “job file”. When you edit the mpeg-1 file you save the result for later
processing. Then you start the perl script. This script reads the VirtualDub
job file and extracts the actual data needed to start mpgtx. When all the
segments are there the script starts mpgtx to perform the actual job. HOW TO INSTALL
Install VirtualDub 1.5.10 to a directory. Note that this is not the latest version. You can also try other
versions, however the methodology and the glue script was tested only with
this version. Also note that the glue script depends on the format of the job
file, which is not guaranteed to remain compatible between versions. The
actual format was used as the version mentioned above using experiment and
not documentation of the format. To install VirtualDub all you need is to extract the
files to a directory and create a short cut to VirtualDub onto the desktop.
The version 1.5.10 that I use to edit mpeg-1 can be downloaded from my site
from here
(667KB). The advantage from downloading the code from here is that the
archive contains the glue script as well, so you can install the script and
VirtualDub in one shift. Install perl 5.8.4 using ActiveState Perl
interpreter. I do not provide the actual version here, because the kit is
quite big and because later versions should also work executing the glue
script. There is nothing special in the script that would require the
specific version I used to test the glue script. Installing ActiveState Perl
is quite easy: download, click on setup.exe (or some .msi file) and click,
click, click. Do let the installer associate the extension pl with the
interpreter to ease life. Install mpgtx! You can download it from SourceForge and installing is simply
copying the file mpgtx.exe to a
directory, which is in the path. I recommend copying it to the directory
where the perl interpreter is. It is usually C:\Perl\bin. Download the glue script and copy it to the
directory where VirtualDub is. Name the script to vd2mpgtx.pl. You need not do this if you downloaded the copy of VirtualDub from
the ZIP file provided on this site. In that case the glue script is already
in the directory where it has to be. The final step is to create two shortcuts on your
desktop. One is for VirtualDub and the other to vd2mpgtx.pl. Open the properties dialog of the shortcut pointing to vd2mpgtx.pl and ensure that the field “Start
in:” points to the directory where VirtualDub is installed. This is
very important because the script looks for the job file in the actual
directory. HOW TO USE IT
Thus the actual editing of mpeg-1 files is the following: ·
Start VirtualDub using the
desktop shortcut. Press F4. This will open the pending jobs. These are the
jobs that were actually performed by vd2mpgtx but VirtualDub believes they
are pending. Delete all previous jobs from the list. ·
Load the mpeg-1 file to
VirtualDub. It may take some time and display a lot of warnings, but you can
safely ignore them. I am not too much familiar with the mpeg-1 format and I
do not know what they mean, but I have never had any problem with those. ·
Edit the film, cutting off the
ads. Most probably you record the movies automated thus you will have some
extra ads in front of the film and some other garbage at the end of the
mpeg-1 file. You can cut off those also. ·
Open the “save as
avi” dialog box and check the check box at the bottom left that reads:
“Don’t run this job now…” Specify a name for the file
(do not care the extension, the glue script will rename it to mpg anyway). ·
Start vd2mpgtx.pl using the desktop shortcut. When it starts it displays how it
performs. ·
Enjoy the created ad-free mpeg
movie. REFERENCES ·
Mpgtx ·
Peter Verhas
creator of the glue script and this page. |