145 Part One: Technical Editing Basics

to everyone you know and invite them to watch your masterpiece!

Four media players have captured most of the mar- ket for playing video and audio files on the Internet: Windows Media Player, which comes with Windows operating software; Apple’s QuickTime Player, which comes with Macintosh operating systems; Flash, cre- ated by Macromedia and owned by Adobe; and Real- Player. There are other players, but these four domi- nate the market. Each offers a free player—for both Windows and Mac operating systems—that can be downloaded from its Web site. Caveat emptor: the Web sites naturally try to persuade you to purchase the full- blown version of each, with which you can create con- tent and not just play it back. The free version is play- back only; you may choose to buy the full version if you wish to use that software to compress your project for distribution on the Web.

Each media player uses its own compression algo- rithm—the mathematical formula for removing re-

dundant information from video and audio files to make them smaller and more suitable for sending and downloading via the Internet. Many content cre- ators compress their files with at least two of the dominant media players—Windows and Quick- Time—because these come loaded on every com- puter: Windows on PCs and QuickTime on Macs. Many use RealPlayer, as well, because of its popular- ity. Flash usage has grown in recent years because nearly every computer has it and because the popular video website YouTube (owned by Google) uses Flash. If you choose to use just one compressor, it is recommended that on the homepage for your project you let readers know which media player they will need to view your video, and provide a link to the Web site from which they can download the free viewer. For example, if you use Windows Media Player, you might direct Macintosh users to the “flip4mac” Web site to download the free software that plays Windows Media files within QuickTime.

Figure 7-5 A screenshot from DVD Studio Pro. This is set up to author a DVD, including a menu that allows viewers to select certain segments by assigning them chapter markers. (Courtesy of Apple)

146 Chapter 7: Part One: Technical Editing Basics

Technical Concepts

When working with video, you can gain a better un- derstanding of the editing process by familiarizing yourself with some key terms and concepts that ex- plain video recording and playback. A solid grasp of the fundamental technical aspects of video should pro- vide a good context for understanding what happens technically during editing.

Scanning

The chapter on video explains in detail how a camera converts light coming into the lens into an analogous electrical signal for recording. If it is a digital camera, it then samples that analogous waveform into a binary se- ries of 1s and 0s. That signal is played back in the same way it was recorded: through a process of scanning. Three different scanning processes make up the global television and video market: the National Television System(s) Committee (NTSC) standard, used in the USA, Japan, and other countries; Phase Alternation Line (PAL), used in Germany, Australia, and other countries; and Séquentiel Couleur À Mémoire (SE- CAM), used in France, Russia, and other countries.

NTSC video is created by a scanning beam that traces out 525 lines on the face of a TV monitor. It does this in two moves, called interlaced scanning. (See Figure 7-6.) It scans first the 262.5 odd-numbered lines and then the 262.5 even-numbered lines. This entire scanning process occurs 30 times per second (ac- tually 29.97 frames per second [fps] for historic engi- neering reasons that have to do with image stability when TV migrated from black-and-white to color). Thanks to our persistence of vision, this is fast enough to allow our eyes and brains to believe that we are seeing a solid, constant image.

Fields, Frames, and Segments

The complete scanning of either the odd or the even lines forms a half-picture known as a field.Two fields, when combined or interlaced, form a frame or complete picture. In some tape formats (e.g., older one-inch type C), a frame is encoded onto tape in one continuous line and is called a nonsegmented format.

Other formats (e.g., mini-DV) that encode each frame

on a separate line are called segmented formats. (See Figure 7-7.) The nonsegmented format allows for some special effects, like noise-free slow motion or freeze-frame, without using a time-base corrector; seg- mented formats require time-base correction.

Tracking and Skew

When video is recorded on any tape format, it is re- corded at a particular speed with the information placed onto the tape at particular locations and angles. The precise way in which the image is laid down on the tape is called tracking. Because each videocassette recorder (VCR) might have slightly different tracking from the next, the tape might play back differently in different VCRs, or “decks.” Many VCRs have a con- trol that allows the playback machine to track very closely to the way the original recorder placed the in-

Figure 7-6 For interlaced scanning, the odd-numbered fields, represented here by solid lines, are scanned first, fol- lowed by the even-numbered fields, represented by dashed lines.

Figure 7-7 Segmented track pattern on a cross-section of mini-DV tape.

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