How Video Editing Works

If you have a camcorder, then you know that it is easy to create home video. You simply point and shoot. However, if you have ever played back what you shot and looked at it, then you know how hard it is to create good home video with nothing but a camera. Even if you are extremely careful when shooting, you usually end up with a lot of "junk" on the tape. When you play it back, it looks like a "home movie" -- amateurish, disjointed, confusing, lousy sound...

Because most of us watch so much television and see so many movies, we tend to have fairly high standards when we watch anything on video. We now expect the following features in almost everything we watch:

A shot is a specific subject filmed from a specific angle. For example, if you are telling the story of your son's birthday party, different shots from the event might include a shot of the cake, presents before they are opened, kids at the party sitting at the table, your son blowing out the candles and unwrapping a present.

If you watch any regular TV show, you will see that it is rare for the camera angle to stay the same for more that 10 or 15 seconds. The director will cut between different angles to keep things interesting or to make different points. For example, the screen might show a man's face while he's talking for five seconds, and then switch to a shot of his hands holding a tissue (while the sound track continues uninterrupted with him talking) to show the emotion.

Even if you are trying to present something as simple as your family trip to the zoo, it is nice to include as many of these features as possible in your rendition of it. The more features you add, the more professional your work looks and the more attractive it is to your audience.

The good news is that, with just a camera, a computer and a piece of video editing software, you can create video masterpieces that include all of these features.

There are a million different ways to do video editing. You can buy a complete solution from a company like Avid at the high end, and at the low end you can use your camera and a VCR to cut things together. The solution that we are going to discuss in this article involves three different parts:

Let's look at each of these parts in turn.

There are hundreds of digital video cameras, or camcorders, on the market today from manufacturers like Sony, Panasonic, JVC and Canon. Most of them use what are known as MiniDV tapes like the one shown on this page.

Just about every camcorder based on the MiniDV tape format includes a FireWire (IEEE 1394) port on the camera so that you can load the video onto your computer quickly and easily. The following three cameras are typical of digital camcorders on the market today.

Whichever type of camera you pick, it needs to have a FireWire connection so you can hook it to your computer. A FireWire connection normally looks like this:

Next, we'll learn about computer requirements and the software.

You can use just about any desktop computer for video editing, as long as it has:

Video processing in general uses lots of CPU power and moves tons of data on and off the hard disk. There are two different places where you will most feel the benefits of a fast machine and the sluggishness of a slow one:

I have one Pentium 3 machine running at 500 MHz, with 512 MB of RAM and a decent 20-GB hard drive. It is right on the edge of being able to handle the data stream from the FireWire connection. It can not handle it if any other applications (like an e-mail program) are running. A Pentium 4 machine or a late-model Mac with 512 MB or 1 GB of RAM and a big hard disk is a nice machine to have when you are rendering and writing files.

The Software There are many software packages available for editing video on your computer. Windows XP even ships with software that's built into the operating system. Machines from Sony and Apple have software that comes with the machines.

In this article, we will use a software package called Adobe Premiere to demonstrate the video editing process. We are using Adobe Premiere for two reasons:

In order to use a package like Adobe Premiere, you need to understand several basic concepts. Once you understand those basic concepts, however, the whole process is remarkably easy. After you are familiar with the fundamentals, it is extremely easy to expand your repertoire to include all sorts of advanced techniques.

Next, we'll look at the four most important concepts you need to understand from the start.

So far, we've discussed the equipment you will need to edit video. Now let's learn the basic concepts you will need to know in order to use that equipment.

Capture

The first concept is called capture. You have to move all of the footage out of the camera and onto your computer's hard disk. There are three ways to do this:

If you have just a few minutes of footage, technique #1 is the way to go. If you have an hour of footage, techniques #2 and #3 are useful.

AVI and MOV files The capture process will create AVI (on the PC) or MOV (on the Mac) files on your hard disk. These files contain your footage, frame by frame, in the maximum resolution that your camera can produce. So these files are huge. Typically, three minutes of footage will consume about 1 gigabyte of space. You can never have enough disk space when you do a lot of video editing. The Mac we use here at HowStuffWorks for most of our editing has almost 300 gigabytes of fast SCSI disk space, and Roxanne is always having to archive stuff off of it to make room for the new material we are working on.

Shots Once you have all of your footage into your machine, you need a way to select the parts that you are going to use. For example, let's say that you want to include a scene in your birthday movie that shows the candles on the birthday cake being lit. You filmed this activity from three angles and have three minutes of raw footage total. But in the final movie you are going to have 15 seconds of the movie devoted to this scene, in the form of three shots:

Out of the big file of all the footage, you need a way to mark the beginning and end of these three little clips so that you can move them around as individual units and bond them together into the final scene.

You do this by looking at the raw footage and marking an IN and OUT point for the little sections that you want to use. Then you drag these little clips onto the timeline.

Timeline Once you have your shots figured out, you need a place to arrange them in the proper order and hook them together. The place where you do that is called a timeline. You line the shots up in sequential order. Then you can play them as a sequence.

With just three concepts -- capture, shots and timeline -- you can make a movie. It will not be fancy, but it will be 10 times better than watching raw footage. Let's run through these steps and create a movie with them.

Once you have installed Adobe Premiere on your PC or Mac, (see this page to download a free demo version), start the program. The first thing that you will see is this dialog:

You can click OK here and move on to the next step, but if you'd like to understand what this dialog is talking about, here's a quick description:

If you are using a MiniDV camera in the United States and you are shooting standard rather than widescreen, then the default that Premiere chooses is correct. Otherwise, choose an appropriate option for your situation.

Once you get past the Project Settings dialog, you come to the main working screen of Premiere, which looks something like this:

There are five different areas on the screen that are important.

Let's look at the process of editing a video with Adobe Premiere.

After you shoot raw footage with your camera, you need to load that footage into your computer. To do this, connect your camera to your computer with a FireWire cable. Select the Capture... option in the File menu of Adobe Premiere. You will see a window like this:

The controls at the bottom of the Capture dialog let you control your camera. You can rewind, fast forward and play. Typically, what you would do is:

You can either capture all of your footage in one big file, or your can capture it in a number of smaller files. (Note that some operating systems and video editing software packages limit file size to 2 gigabytes. Other packages limit file size to 30 minutes. You also need to make sure that you have enough free disk space to hold all the captured footage.)

Premiere will create AVI (on the PC) or MOV (on the Mac) files on your hard disk at a rate of about 1 gigabyte per three minutes of raw footage.

As an example, look at this piece of raw footage from the zoo:

The footage is 35 seconds long, and the AVI file that Premiere created when it captured the footage is 130 megabytes. We've converted the raw footage into an MPG file so that you can view it on the Web. It is typical "raw footage" with all sorts of debris and problems that you find in most raw footage. In the next section, we'll see how to clip out one usable piece from the raw footage.

Clipping

Let's take the shot of the cougar from the previous section as an example . It's a decent shot of a cougar lying on the ground for 30 seconds. In the middle of the shot the cougar yawns. Let's say that you would like to clip out the yawn and use it in your movie. To do this, take the following steps:

There are several ways to mark the IN and OUT points. As you are playing the video, probably the easiest way is to hit the I and O keys on the keyboard when you see the IN and OUT points. Once you rough them in, you can fine-tune them with the mouse by dragging them.

Now that you have selected a clip, you can add it to the timeline.

Once you have marked a clip by selecting the IN and OUT points in the Source window, you can add the clip to the timeline. Simply drag the image from the Source window down to the timeline. You will see something that looks like this:

What the timeline now shows is that your movie contains one clip, about five seconds long.

Now what you can do is repeat this process and drag several more clips onto the timeline. You will end up with something like this:

This is the simplest possible movie -- a bunch of clips strung together on a timeline. But it is a movie nonetheless, and it is 10 times better than raw footage because you have chosen the best parts of the raw footage to assemble on the timeline. To play your movie, you can click the play button on the program portion of the monitor area, or you can click in the time portion of the timeline area to move the pointer and then press the space bar to start playing from that point.

Let's say that you would like to change the length of a clip once you have it on the timeline. There are several ways to do this:

Transitions Sometimes simple cuts from one clip to the next work well, but other times you might want to use fancier transitions from scene to scene. For example, you might want to use a dissolve, or a wipe or a fade. Premiere has all sorts of transitions available. Simply choose one from the transitions area and drag it to a spot between two clips on the timeline:

Once in place on the timeline, right-click on the transition to adjust it if you like. The transitions will look like this on the timeline:

When you play your movie, you will not be able to immediately see how the transition will actually look. That's because transitions take some extra processing to complete the effect. Premiere tells you that extra processing still needs to be done by putting a small red bar above the transition, as seen in the previous illustration. To activate the extra processing, you Render the timeline. From the Timeline menu, choose Render Work Area. When the processing is finished, you can play your movie to see the transition.

In the next section, we'll learn how to add music and sound effects to your movie.

When you shoot your raw footage with your camcorder, it has a sound track. There are three reasons why you might want to supplement or replace the existing sound track:

To handle music, you have several options:

You can import many different types of sound files (including WAV, AIF, etc.) into a Premiere project and then position it on the timeline in Audio Track #2. Now when you play your movie, Premiere will automatically mix the original sound track of your movie with the new audio track and play it.

To handle narration, probably the easiest thing to do is simply read your narration into the camera, and then capture the video as you normally would. You can separate the narration sound track from the video track and use the sound track. Simply drop the raw narration footage onto the timeline, right-click on it and select "Split Video and Audio." Click on the video portion and delete it. Now you have the narration sound track that you can lay on the timeline at the proper point.

Particularly with narration, timing the video with the audio becomes important. Once you have the narration sound track on the timeline, you can slice it up with the razor blade tool to either add gaps or delete sections to help with timing.

In a big project, it is not unusual to be working with half a dozen sound tracks. Premiere can manage an unlimited number of audio (or video) tracks. To add a new sound track, all you need to do is right-click on the timeline and select the Track option. Select to add a new track.

Any TV program or movie that you see today contains B-roll. In the vernacular, A-roll is raw footage where there is a person on-screen talking. B-roll is everything else. If you were to film a high school play, the raw footage would be almost pure A-roll. On the other hand, a nature documentary can be created with nothing but B-roll, and then a narration is laid over the top of it. If you are creating a movie that explains something, it is very common to use B-roll to provide close-ups of the thing you are explaining. You see this technique all the time in any video that HowStuffWorks creates.

The process of cutting a piece of B-roll into a piece of A-roll is often referred to as a split-edit. For example, earlier in this article we talked about a scene where someone is talking on camera about an emotional topic. In the middle, the director cuts to a tight shot of the person's hands holding a Kleenex. During the scene, you see the person talking, then the Kleenex, and then return to the person's face, and the sound track is uninterrupted by the B-roll.

To add B-roll and create a split-edit in Premiere, you simply add the B-roll footage to the time line using video track 2. Premiere's protocol is to use whatever video is in the highest numbered track when playing the movie. For example, let's say you set this up:

You have the shot of the polar bear lying around. For contrast, you want to cut to a shot of two grizzly bears wrestling. You simply place the grizzlies on video track 2. When Premiere plays the movie, you will see the polar bears, then the grizzlies and then back to the polar bears.

In some cases, you want to completely discard the sound track of the B-roll. Right-click on the B-roll and select "Split Video and Audio." Then click on the audio portion and delete it. Or you may want to eliminate the sound in the original footage. We'll see how to do that easily in the next section.

If the visual part of a movie is perfect but the sound is not, then the movie looks amateurish. Fortunately, Premiere offers sophisticated tools for getting the sound right. We've already discussed how to add new sound tracks to the timeline. Now you need to understand how to adjust each sound track so that everything sounds perfect.

On every sound track, there is an arrow icon. Clicking it will expand the view and make an adjustment area for the sound track available, as you can see here:

In this adjustment area, you can add new control points simply by clicking anywhere along the red line. Then you move the control points by dragging them with the mouse. The control points control the level of the sound. For example, in the following illustration, the level of the sound in video track 1 has been taken to zero so that the sound on a split-edit is used instead:

What you will normally do is listen to the sound track and "even out" or "sweeten" the sound by adjusting things so that the sound is uniform throughout your entire piece.

It is important to mention that having a good microphone can really help sound quality, especially when you are filming someone talking. A good lavaliere microphone (the kind that you clip onto the front of the speaker's shirt) can make a huge difference. Lavalieres come in both wired and wireless versions. You will especially notice the advantages of lavalieres when you are filming indoors -- a lavaliere will completely eliminate the echoes and "booming" sound that you will frequently get from recording someone indoors with the camcorder's built-in microphone. Check out Shure's Wireless Microphone Systems for details.

For more information on digital video editing and related topics, check out the links on the next page.