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Broadcast 2000 Brings DV Editing to Linux

by Curtis Lee Fulton

Why I Prefer the Open Source Solution for Video Editing

A personal note from Curtis Lee Fulton about why he prefers to use the open sourced "Broadcast 2000" editing application over other solutions such as Final Cut Pro.

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As digital video cameras drop in price and bandwidth widens with every DSL and cable hook-up, the notion of producing concise interesting video productions and streaming them over the Web is becoming more plausible every day.

Apple Computer has energized this phenomenon with its consumer-level "iMovie" DV editing application. Software developers for Windows, such as Ulead, have also been busy marketing their nonlinear editing packages.

But editing packages, even the high-end ones such as Avid or Final Cut Pro, are just that, packages. Neat little black boxes that give the artist little hope of breaking the mold. By contrast, GNU/Linux gives you only the media and the medium, which is simply a string of pictures stored on your hard drive, played back in whatever order and at whatever speed you command the machine to do. These strings of pictures can be accessed at any time by any program or even other computers.

Broadcast 2000

Broadcast 2000, created by Adam Williams, is the mechanism that stitches the artist's media together. It will work with any size frame, any frame rate, and any number of audio tracks. Even by itself, Broadcast 2000 can add all sorts of effects.

The Broadcast2000 main window.
The Broadcast2000 main window. Two tracks can be seen here: one video track and one audio track. Notice the patchbay on the left and the transport at the top.

Broadcast 2000 is a non-linear editing system. This means that no part of the working media is ever stored in RAM, and it is only stored on the hard disk once. The artist assembles the production by creating an Edit Decision List (EDL), which is sort of like a conductor's score that tells Broadcast 2000 when to start/stop playing certain media clips.

At any time, a saved EDL can be loaded, which will erase the current EDL. If the chosen file is just a media file, then a new EDL will be created, bringing the media file's start and stop points into the newly created EDL.

Saved EDLs or media file entries can be appended to the current EDL as well. In Broadcast 2000, "append" refers to space, not time. The easiest way to visualize this is to think of a stack of film splices. To Broadcast 2000, sliding a new film slice under the others is "appending" it to the stack. In Broadcast 2000, every layer in that stack is a separate track. Tracks are always played at the same time, which would be a bit like gluing all those film splices on top of each other and running them through a projector.

When a media clip is appended, Broadcast 2000 considers it an "asset" and indexes it. When a clip is indexed, bits of information about the clip are stored in memory. This information is used to represent the clip visually in the EDL.

Often called a "bin" in non-linear packages, the asset manager is a list of all the media files Broadcast 2000 currently considers assets. Assets and all EDL references to an asset can be removed by using the asset manager.

Currently, the simplest way for the artist to get his or her footage into the machine is to use Video4Linux. This API works with most computer TV cards. TV cards usually have a jack where a VCR or camcorder can be connected. Broadcast 2000 has built-in support for Video4Linux, so the artist can digitize footage without leaving Broadcast 2000.

To use Video4Linux, the proper modules must be loaded or compiled into the kernel. Instructions for this task are outside the scope of this article. More information about the Video4Linux drivers can be found at the Video for Linux Resources Page

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Before digitizing, the artist should choose the desired video frame rate and audio sampling rate. The frame rate is set by choosing Video|Framerate from the main menu bar. The bit and sampling rate is chosen by selecting Audio|Sample rate from the main menu.

To begin digitizing, click on the record button, which is the one with the red dot in the middle of it. The first box that pops up is where the artist specifies the format of the digitized media. For now, the artist should choose a file format of Quicktime, with the following options set:

  • Audio: 16 Bits, signed.
  • Video: RGB compression, with a quality of 68.

The artist should make sure that "render audio tracks" or "render video tracks" is selected only if video or audio recording is desired. After clicking "Do It," the artist will see two new boxes pop up. The box filled with black or TV "static" is the preview window. The preview window allows the artist to see what is being captured, in real time. Above the preview window is the recording transport.

The recording transport works basically like a tape recorder: It will fast forward, record, stop, and play. In addition to the basic record and play buttons, there is a record-and-play button, which will play back all audio tracks as it records.

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