A Short Lesson in Video Formats

If you have a standard, miniDV camcorder and you're anxious to start making movies, feel free to skip this little lesson and move on to page 226. But if you want to use video from a different kind of deviceor you're curious about one of iMovie HD's most intriguing capabilitiesread on.

Just as music and photos can be stored in a variety of digital formats, video also comes in several flavors. And, as with music and photos, each video format takes its own approach to organizing the bits and bytes that make up your media.

In early iMovie versions, projects were based on one video format: DV. You could import other formats into iMovie, but iMovie would convert that footage into DV format. DV was iMovie's native tongue, and using other formats meant a translation step that took time, used up disk space, and often compromised video quality.

Times change. New types of video devices have appeared, and iMovie has evolved to keep pace: iMovie HD provides native support for several video formats. iMovie HD is multilingual, and as a result, you have the flexibility to edit video from a wider variety of video devices, ranging from Apple's inexpensive iSight to many digital camera models to the new breed of high-definition HDV cameras from companies such as Sony and JVC.

iMovie HD's basic operation is identical regardless of which video format you use. There are some subtleties to some formats, and I'll share them as we go. But first, let's look at the video languages iMovie HD understands.

How Square Are Your Movies?

Many of the differences among video formats aren't visible at first glance, but one of the differences definitely is: the aspect ratio of the video frame.

We encountered the concept of aspect ratio when looking at iPhoto cropping techniques (page 137). The phrase simply describes how square or rectangular an image frame is.

Early iMovie HD versions were limited to one aspect ratio: the standard 4:3 ratio used by most TV sets, DV camcorders, and digital cameras.

Going wide. iMovie HD adds the ability to work with and create widescreen video in the 16:9 aspect ratiothe format common in high-definition TV sets.

The widescreen format provides a more cinematic experience.

Pronunciation guide. Making video small talk at the local coffee shop? The expressions 4:3 and 16:9 are usually pronounced "four by three" and "sixteen by nine." Technically, "four to three" and "sixteen to nine" are more accurate, since these expressions are ratios. After all, when was the last time you heard a bookie describe "2 by 1" odds on a horse?

In this chapter, look for the for information specific to HDV editing.

Choosing a Video Format

Normally, iMovie HD projects are based on the DV format. If you're using a standard miniDV camcorder with its factory settings, you don't have to bother with choosing a format since iMovie HD is preset to speak its mother tongue.

If you're using a different kind of device or you've set your DV camera to 16:9 mode, you need to tell iMovie HD which format to use. You do that when creating a new project.

DV. By far the most common format used by digital camcorders, and the format iMovie HD uses for any new project unless you specify otherwise. Now that the era of high-definition TV is upon us, the DV format is often described as a standard definition format.

DV Widescreen. Most DV camcorders can shoot in widescreen mode, often by simply cropping the top and bottom of the video frame. (To shoot in this mode, use your camcorder's menus to activate 16:9 mode.) You don't get the picture quality of high-definition TV, but you do get that cinematically wide image.

HDV 1080i and HDV 720p. High definition (HD, for short) TV is gradually gaining momentum, and the new breed of HDV camcorders is helping. The HDV format brings high-definition videography to advanced amateurs and budget-minded professionals (and, as prices come down, to the rest of us). HDV always uses a 16:9 aspect ratio. For more information on the HDV format, see page 262.

MPEG-4. Many digital cameras shoot their movie clips in this format, as do a growing number of compact video cameras that connect via USB. For tips on importing and working with MPEG-4 clips, see page 263.

iSight. Apple's inexpensive iSight camera, which is built into some current Mac models, is designed for video chatting using iChat AV, but makes a great low-budget TV camera, too. For advice on shooting with an iSight, see page 263.

Mixing Video Formats in a Single Project

Sometimes, you may want toor have tomix video formats within a single project. Maybe you have a digital camera movie clip that you want to add to a project that's in DV format. Or perhaps you have some 16:9 DV footage that you want to include in a 4:3 DV project. Or maybe you're making a montage of MPEG-4 digital camera movies, but you're using the DV format so you can output the final montage to a miniDV camcorder.

You can do all of these things and more. If you import a movie clip in which the video format differs from your project's format, iMovie HD converts the clip into whatever format your project uses. This conversion process is called transcoding, but you can also call it waitingit can take a long time. And use a lot of disk space.

Say you import an MPEG-4 digital camera movie clip into a DV project. The movie clip might have a small frame size and use only 20MB of disk space, but in order to make it compatible with your DV-based project, iMovie HD will change its frame size and other characteristics to conform to the DV standard. The DV version of that movie might take up 120MB.

For these reasons, it's best to stick with one video format within a single project. But when you don't have a choice, iMovie HD is readyprovided you have the time and the disk space.