Understanding the DV-AVI Workflow

When working with Premiere Elements, as with any video-editing software, it's important to understand the difference between digital and analog video. In simple terms, it's the difference between a clock and a digital watch or between a record album and a CD.

In the old days (actually more like 10 years ago), consumer camcorders recorded video the way tape recorders record sound. Impulses of light and sound were translated into electronic pulses that were recorded magnetically onto a moving tape. Naturally, the quality of those pulses was limited by the camera's optics, the quality of the recording head, and the quality of tape. But the biggest liability was that every time a copy was made of the video, it was merely an analog attempt to reproduce an analog signal. With each copy, the quality of the recording diminished. Every generation of the video was a continually degraded approximation of the generation before.

Digital video was a major step forward for video quality. Rather than simply capturing electronic impulses of light and sound, digital video takes approximately 25 or 30 snapshots of more than 450,000 pixels of light and thousands of samplings of sound every second and records them not as electronic pulses but as binary codeexactly the same binary code your computer uses. The quality of this data is limited only by the camera's light and sound sensors. More importantly, when a copy is made, rather than simply approximating the original recording, the data itself is transferred from one source to anothermeaning that each copy of the digital data is identical to the original recording!

KEY TERMS

Digital video Also called DV, it is video that records sound and motion as computer data, or chains of 1s and 0s.

Pixel The basic building block of digital images. Although they seem to be painted with continuous color, digital imageson television, on your computer, or in your digital cameraare actually composed of tiny rectangles (pixels) of various settings of red, green, and blue color. In most cases, pixels are so small that they blend into a smooth flow of color. However, when an image is stretched beyond its intended resolution, or over-rezzed, the pixels become visible, and the image appears jagged or pixelated.

When transferred into your computer using an IEEE-1394 connection (commonly called FireWire) or USB Video Class 1.0, the video data stream from your digital camcorder remains virtually unchanged. The computer merely packages the digital video (DV) data into DV-AVI clips. You can edit those clips, cut them, and reassemble them. When you output the data back to your camcorder, it comes out in the same type of binary code stream as it went in. In other words, when working from a digital video camcorder and using a DV-AVI workflow, your camcorder and computer speak the same binary language (see 4 About Video Capture).

KEY TERMS

FireWire Initially a brand name for Apple's high-speed data connection, it has become universal shorthand for any OHCI-compliant IEEE-1394 connection. It is also the current standard for transferring digital video data from a camcorder to a computer and back again.

USB Video Class 1.0 A relatively new high-speed standard for transferring digital video from specially equipped camcorders to a computer over a USB 2.0 connection.

NOTE

The two forms of digital video available on consumer camcorders are miniDV and Digital8. The differences are minor. They both use exactly the same method for coding and transferring the digital video informationand they both create identical DV-AVI data streams when connected to a computer. The only difference is in the media themselves. MiniDV uses a small cassette specifically designed to work in miniDV camcorders. Digital8 uses slightly cheaper 8mm videocassettes (Hi-8 tapes are recommended). Additionally, many Digital8 camcorders can also play 8mm and Hi-8 analog tapes, an advantage when it comes to transferring video from these tapes into a computer.

DV-AVI is the lingua franca of PC-based video editing. All video-editing applications speak it fluently, and it is the highly recommended format for transferring files between your camcorder and your computer and its editing program and back again.

Premiere Elements, like virtually all PC-based nonlinear editors, uses a DV-AVI workflow. That means that no matter what you put into itphotos, graphics, or other video file formatsPremiere Elements assimilates it as some form of DV-AVI (ultimately delivering the final product as a DV-AVI). This is one of the reasons Premiere Elements can sometimes find it challenging to work with MPEGs, QuickTime, Windows Media, and other video files.

KEY TERMS

DV-AVI A PC-based video file format, designated by the file extension .avi, but distinguished from other kinds of AVI files by its use of the near-lossless DV codec, or file compression system. Because of its perfect balance of size and quality, it is the preferred video format for PC-based video editors, as well as being the universal language that all PC-based video-editing software speaks.

MPEG A video file format developed by the Motion Picture Experts Group, MPEGs use a temporal compression system, a system of compressing the file by re-using repeated elements from frame to frame, that produces very small filesalthough they are sometimes technically challenging to edit. Although Premiere Elements 2.0 can work with MPEGs, you should consider them to be chiefly a delivery format (the files you burn to your DVDs) and not the preferred format for editing.

A number of products are available that convert analog video into a digital file for your computer. Although Premiere Elements 2.0 is capable of handling a wide variety of video file types, it's always to your advantage to use a product that produces DV-AVI files. We recommend a few modestly priced pieces in 8 Capture Analog Video.

For more information on transferring your camcorder's video into your computer, see 4 About Video Capture. And for information on capturing video from DVD and MicroMV camcorders, as well as from unusual sources such as digital still cameras and picture phones, see 14 Add Media with the Adobe Media Downloader.