Video editing in Linux, it *is* possible

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Video editing is probably one of the last areas where Linux is still lagging behind proprietary operating systems. I have used Linux almost exclusively for the last few years, except for video editing where I still use Windows. That is about to change.

My goal was to build a video box that would let me grab video from my digital video (DV) camera, edit scenes with features such as transitions, and create full featured DVD recordings. My hardware is very low end for this kind of task and it has proven to be extremely slow under Microsoft Windows. The test machine featured a 1.3GHz AMD Duron processor, 512 MB of RAM, a 4X single layer DVD burner and a Pinnacle firewire video capture card. Due to my low-end hardware, I decided to install the Slackware 11 distribution. Slackware is known for good performance on limited hardware.

Capturing Video

The initial requirement for a video editing system is the ability to capture the video data. Two choices were available: Kino and dvgrab. Kino is easy to use and even allows you to control your DV camera from a nice GUI interface. Kino requires some GNOME libraries, but Slackware does not provide them out of the box.

I chose to use dvgrab for video capture, it operates with a very simple to use command line interface. For installation of dvgrab on Slackware, you will need to install the following packages (available here): libiec61883, libraw1394, libavc1394, libdv, libsamplerate and dvgrab. Once installed, dvgrab complained about the lack of the IEE1394 interface, /dev/raw1394. Fixing that problem involved creating two device nodes:

    mknod /dev/raw1394 c 171 0
    mknod /dev/video1394 c 172 0

Finally, due to a permission issue, I opted to use the root account for capturing video with the following command:

    dvgrab video_file_name

The ownership of the resulting video file was then changed to my regular user for further processing.

Video Editing

The next step, and the most complex one, is video editing. The only effective video editor that I found was Cinelerra CV (community version). Until recently, Cinelerra was very unstable software and was not an attractive solution. You had to save very often because of the high risk of crashing. With the latest release, I experienced absolutely no crashes, and I performed some very wacky editing tricks with the software.

The installation process for Cinelerra CV is not trivial if you decide to compile the source yourself. Luckily, the latest version and its dependencies are available for Slackware 11. Selected packages include: faac, faad2, fftw, jack, lame, liba52, libdv, libquicktime, libsndfile, libx264, mjpegtools, openexr and cinelerra.

The Cinelerra interface can be rough at first, but after a few hours of editing you will discover that it is rather usable. Basically, you just import the videos obtained through dvgrab, create clips from the video files, drag the desired clips to the various tracks, insert transitions, apply effects, and finally render your work.

The Cinelerra wiki offers a clear explanation on how to use the various components of the software. You can do tasks such as compositing various video tracks and using multiple audio tracks for dialogs, music, narration and more. Unlike various commercial video editing solutions on the Windows platform, it is not necessary to pay fees for incremental features, such as using a second video track.

Rendering the video

Once you are satisfied with your work, it is time to render everything to a file format that will work with DVD players. Since this step is a tricky and frustrating one, I provided the various steps (also available in the Cinelerra CV wiki) that you need to perform to reach success:

• Create a script ~/cine_render.sh with the following two lines:

  #/bin/bash
  mpeg2enc -v 0 -K tmpgenc -r 32 -4 1 -2 1 -D 10 -E 10 \
           -g 15 -G 15 -q 6 -b 9400 -f 8 -o $1
  

• Add execute permissions to the script:

      chmod +x ~/cine_render.sh
  

• Open Cinelerra, and select the part of the video you want to render with the [ and ] points.

• In Cinelerra, press Shift+R to bring up the render menu.

• Select the "YUV4MPEG Stream" file format.

• Deselect "Render audio tracks" and select "Render video tracks".

• Click on the wrench that shows up near the word Video.

• In the newly opened window, indicate the name of the m2v file that you want to create. The m2v file will contain only the video.

• Click on "Use pipe" and enter the path of the previously created script:

      /home/[your username]/cine_render.sh %
  

• Click OK to close the second window, and OK again to render your m2v file.

• After the m2v file has been rendered, open the rendering window again and render an ac3 audio file, choose the 224 kbit/sec sampling rate.

• Finally, combine the audio and video tracks with this command:

      mplex -f 8 your_video_file.m2v your_audio_file.ac3 \
            -o video_audio_file.mpeg
  

The resulting mpeg file should be compatible with commercial DVD players.

Creating a DVD

You now have the data to create a DVD. Several tools are available for this task, but ManDVD stands out as being very easy to use and full of features. To use this application, you will need to install the following Slackware packages: mplayer, ffmpeg, transcode, libdvdread, dvdauthor, dvd-slideshow and mandvd.

ManDVD allows you to write DVDs. It featuring animated menus and can be operated without touching the command line. ManDVD can burn the final product directly, or it can use K3b for this task. In my case, K3b failed to create a working DVD, so I recommend burning directly from ManDVD.

Afterthoughts

Two new gstreamer-based video editing solutions are being developed at the moment, diva and PiTiVi. These two projects will eventually provide simple out of the box solutions for the various steps involved in movie creation. PiTiVi will also introduce some exciting new features, such as post-processing of screencasts created with Istanbul and collaborative video editing via bittorrent. The Diva and PiTiVi projects are under heavy development and would benefit from the help of additional hackers.

Until those new alternatives become usable, you will need to rely on a combination of specialized tools to fulfill your video editing needs. With a minimum of pain and time, it is now possible to create professional looking home movies using an entirely free solution running on the Linux platform.

Index entries for this article
GuestArticles	Bolduc, Carl

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