How AVID Editing Machines Work

The introduction of non-linear editing with computers in the early 1990s was nothing short of revolutionary. To understand why non-linear editing with a system like Avid is so powerful and efficient, first we need to understand the differences between non-linear and linear editing.

Linear editing means that a project is edited and assembled in a linear fashion -- from start to finish. Linear editing is most common when working with videotape. Videotape, unlike film, can't be physically cut into pieces and spliced together in a new order. Instead, the editor must dub or record each desired video clip onto a master tape.

Let's say you have three source tapes, labeled A, B and C. In linear editing, the editor decides which source material he wants to use first, second and third. In this case, he wants to use material from tape C first, then B and A. He starts by cuing up tape C to the beginning of the clip he wants to use. Then he plays tape C while simultaneously recording the clip onto a master tape. When the desired clip from tape C is done, he stops recording. Then he has to do the same thing for the clips on tapes B and A.

In non-linear editing, however, the editor has the ability to edit any segment of the project in any order he wants. He can cut, copy and paste clips from one part of the project to another just like you can cut, copy and paste text with word processing software.

Interestingly, traditional film editing was always non-linear. A filmmaker could cut his film up into pieces and splice it together in any order he liked. However, this cut-and-splice process was painstakingly slow, greatly limited in transitions and effects and left a lot of room for error.

Modern non-linear editing is entirely digital. Video or film source material is digitized into media files that can be stored on a hard drive. Using video editing software like the Avid Media Composer -- or similar products like Final Cut Pro and Adobe Premiere -- the source files can be organized into clips that are pasted onto a timeline. Using the timeline, an editor can trim clips down to single frames, add transitions, add and edit audio, add effects, and then export the movie back to tape, DVD, film or the Web.

The main advantage of editing with a non-linear system like Avid is speed and flexibility. The director can change his mind a hundred times and the editor has the power to make those changes in real time without having to start all over again. In linear editing, if you decided to replace a clip with a new one, you'd have to overdub onto the existing clip and hope both clips are the same exact length. If the new clip is too short, you'll leave the tail end of the old clip on the master. If it's too long, you'll roll into the next scene. Meanwhile, all that overdubbing degrades the image quality.

Avid has long been considered the industry standard for professional digital video editing. Read on to learn more about the different components of an Avid system and how they work together to make the editing process not only faster, but also more creative.

The heart of an Avid non-linear editing system is the Media Composer software. The software provides the user interface through which an editor accesses the tools and system functionality. The Media Composer interface is broken down into three basic areas: the bin, the monitor and the timeline. This three-part system has been adopted by pretty much every other video editing software out there, from high-end products like Final Cut Pro to amateur software like Apple iMovie.

The bin is where the editor stores all the different project components. It not only holds digitized video clips, but digital audio files, images and any other source material that'll be assembled into the final project. In the bin monitor, the editor can adjust the properties of each individual component, trimming the length of clips, adding effects, smoothing jittery video and adjusting audio levels.

The monitor is actually composed of two small screens. The left screen shows a single source video clip and the right screen shows the full project video. This split-screen view is useful for trimming an individual clip before adding it to the project timeline. Once the clip has been added, the editor can preview how it looks with the rest of the project in the right-hand screen.

The timeline area is organized by video and audio tracks. The process is similar to audio editing with a multi-track digital audio workstation. An editor can lay down separate video tracks for credits and subtitles, animated graphics and special transitions. Then he can create multiple audio tracks for dialogue, music and sound effects. The timeline runs chronologically from left to right. In the timeline, the editor can select chunks of video or audio (across multiple tracks if he wants) and cut, copy or delete them with a click of the mouse.

For the home user, or a professional filmmaker on a tight budget, it's possible to run a perfectly good Avid system with nothing more than the Media Composer software and a powerful desktop PC or laptop. But Avid consoles for professional TV and film production typically include additional Avid hardware and equipment.

Avid hardware's role is to make the Media Composer software run faster and for the whole system to run more efficiently. The hardware box (smaller than a standard desktop PC tower) works like an external video card, helping speed up the digitizing process and the rendering process (for creating visual effects and transitions). The more expensive versions of the Avid hardware allow an editor to use both standard definition (SD) and high definition (HD) video sources in the same project.

The hardware box also includes dozens of useful input and output connections for external digital and analog equipment, both audio and video. In this way, the hardware box serves as a hub between the host computer and external media sources like video cameras, tape decks, memory card readers and DVD drives. The hardware not only imports media from these sources, but can export finished video projects back onto tape, DVD, memory card or any digital file format.

A typical Avid editing suite has at least two computer monitors, one which focuses on the bin and another which shows the monitor and timeline. Professional Avid Editors also use a special keyboard that's color-coded to highlight the short-cut keys. There's also usually a video playback screen -- sometimes a large LCD display -- and plenty of high-capacity external hard drives to hold those large video files.

Now let's look at some of the latest developments with Avid hardware and software and how they're changing the way that editors do their job.

The latest versions of Avid's video editing software and hardware, released in June 2008, include new features that make it easier to edit HD video. With more and more TV networks broadcasting in HD and more consumer HD video cameras on the market, editors need software that can handle the large file sizes of HD video without compromising speed.

Avid has developed a new codec (short for compress/decompress) that compresses HD video into a file size that retains the sharpness and image quality of HD without bogging down the system. The codec, called DNxHD, runs in both the standalone Media Composer software and in the hardware boxes. What this allows is for editors to edit their projects exactly how they will look in full HD. It's no longer necessary to do an offline edit in lower quality and then finish the project on an HD machine.

In the previous version of Media Composer, Avid introduced the concept of the Open Timeline. This means that the timeline can handle clips with wildly different specifications. You can put SD and HD clips side-by-side in the same project, as well as clips with different resolutions, frame rates and aspect ratios. The timeline can also handle audio files with different sampling speeds and file types. In the past, all these differences would have to be reconciled before you could begin editing, which could mean hours of converting files. Now everything works together in real time and is converted when it's time to export.

The newest Avid hardware boxes -- called Mojo DX, Nitris DX and Symphony DX -- are built with the new DX effects architecture. This new system helps distribute the computing and processing load between the host computer and the hardware box, making the system run more efficiently when processing HD or effects-heavy projects. The hardware is connected to the host computer using a PCIE connection that's 20 times faster than Firewire, ensuring lightening fast data transfer.

One new Media Composer tool, called ScriptSync, has already changed the way editors work. Say you're an editor working on a script-based TV drama, like "CSI." For every scene in the show, you might shoot three or four different takes. And within those takes, you might shoot the scene from two or three different angles simultaneously.

Before the editing process can begin, an assistant editor needs to take the script and match each source video clip with its associated lines. They do this to streamline the editing process. When it's time to start a new scene, the editor can quickly cue up the various takes and angles associated with the scene to assemble the best final product. In the past, the job of logging tape and cuing video was half the work of editing.

Now, with ScriptSync, Avid has created a tool that can upload the script as a text file, break the words down into their phonetic parts, and then analyze the audio waveforms of video clips to match them with the lines in the script. All the editor has to do is select the part of the script that he wants to edit. ScriptSync will pull up all of the different takes and angles associated with that part of the script. Then the editor can toggle from take to take and angle to angle to find the best shot for each line of dialogue.

Incredibly, ScriptSync works in nine different languages, including Arabic and Mandarin Chinese.

We hope this has been a helpful introduction to Avid. For more information on editing and video production, view the links on the next page.