WHAT TO WATCH

Lawrence of Arabia is known for its stunning widescreen photography. Also worth checking out: 2001 A Space Odyssey and Dr. Strangelove (just in case you thought widescreen was invented recently).

Describing HD

Because “HD” isn’t one specific thing, the various types of HD video are usually described by three things: the pixel dimensions (or resolution), the number of frames or fields per second, and the scanning method (interlaced or progressive).

720/24p is HD video with a resolution of 1280 720 and a frame rate of 24 progressively scanned frames per second. 1080/60i is HD with a resolution of 1920 1080 and a frame rate of 60 interlaced fields per second. Because 1080/60i is one of the most popular HD configurations for television, it is often simply called 1080i. Similarly, 720/60p is often referred to as 720p. In this book, we use the full description (1080/60i) in order to avoid confusion. We use 720 and 1080 to refer to the entire range of frame rates that share those resolutions.

There’s one more thing to be aware of: interlaced HD video is described by the number of fields instead of frames. 1080/60i has 60 fields per second. Since two interlaced fields of video add up to one frame of video, the frame rate is still 30 frames per second—60i is just a different way of describing the same thing and letting you know that it’s interlaced. Progressively scanned HD video, on the other hand, is described by the number of frames. 720/60p has 60 frames per second.

Audio Tracks

There’s a saying that sound is 50 percent of a movie. Luckily, it’s not quite as complicated as video. Earlier, we said that each HD video file consists of a video track and two (or more) audio tracks. Because an HD file can have multiple audio tracks, they can be configured to work together, or mix, in different ways.

Stereo Sound

Stereo sound consists of two channels of audio mixed together in a special way: one channel is balanced somewhat to the left, and the other is balanced somewhat to the right. When played back, a “stereo” field is created that creates a more three-dimensional perception of where the sounds are coming from.

The only type of production sound that is typically recorded in stereo is music. Stereo sound is usually reserved for the final mix of a soundtrack for a film or TV show. The built-in microphones on most camcorders are stereo, but these mics are usually not suitable for serious production work. You can, of course, buy or rent stereo mics to attach to your camera, and these will record separate left and right channels directly to tape; however, this is not necessary if you are primarily recording dialogue.

42 The Digital Filmmaking Handbook, 4E

Mono Sound

Mono sound consists of one track (or channel) of audio. Almost all of the sound that you record during your production is mono. If you record a line from a microphone into a digital audio recorder, you are probably recording mono sound because most microphones are not stereo microphones—that is, they don’t record separate left and right channels that create a full stereo field. Even if you record onto both channels of the digital audio recorder with a mono microphone, you’re still recording mono: you’re simply recording the same mono signal on the recorder’s two channels.

If you patch a lavalier mic into channel one and let the camera’s built-in mic record to channel two, you are still recording in mono. Granted, you are creating two different mono recordings of the same thing, but the two different channels will sound very different due to the quality of the microphones and their positioning. In no way do they add up to a stereo recording.

There’s nothing wrong with recording mono production sound; in fact, it’s usually considered ideal. You’ll record many different tracks of mono sound and later you (or a sound editor) will mix them together in different ways to get a stereo mix and a surround sound mix.

Recordings Versus Mixes

When you record sound on a movie, typically you record as many mono tracks as you need. Later, when you edit the scene, you typically put several audio tracks together to create a mix.

Surround Sound

For theatrical projection, Blu-ray Discs, DVDs, and HDTV, surround sound is the norm. Surround sound mixes generally consist of 5.1 or 7.1 channels of sound that correspond to the position of speakers in a room or theater. They give an even more intense three-dimensional feeling to the environment than do stereo mixes. (Those .1 channels refer to a subwoofer that provides extra bass.) Mixes and surround sound are discussed more thoroughly in Chapter 15, “Sound Editing” and also in Chapter 18, “Finishing.”

Audio Sampling

Just as a frame of video is broken down into pixels, waves of sound are broken down into samples to create digital audio (see Figure 3.5). The rate at which the audio is sampled can vary, and, as with a video or still image, the higher the sampling rate, the better the quality will be. Professional digital audio is usually sampled at 48kHz (DAT quality) or less commonly at 44.1kHz (CD quality). As a rule, never record at less than 48kHz unless you have a very specific reason to record lower quality sound. Some digital cinema formats can handle 96kHz sampling.

See the section on codecs later in this chapter for a discussion of the different types of digital audio formats.