Apple Final Cut Pro 5 User Manual download pdf (Page 182)

Chapter 14 Determining Your Hard Disk Storage Options 181

III

If your hard disk or its connection to your computer does not support the data rate of

your video format, you need to consider three factors:

Â Sustained transfer speed is a measurement of how fast data can be written to a disk in

MB/sec. When you use a video interface that utilizes M-JPEG compression, the

sustained transfer speed of your hard disk determines the maximum quality of the

video you can capture. Disks with a higher sustained transfer speed allow you to

capture video media files with a higher data rate, which results in higher visual quality.

Â Seek time is a measurement of how quickly data stored on the disk can be accessed

in milliseconds (ms). Low seek times are important when playing back an edited

sequence of clips, because the disk must spend a lot of time searching for the next

clip to play.

Â A faster spindle speed increases a disk’s sustained transfer rate (typical multimedia

disks run at 7200 revolutions per minute, or rpm). However, the faster a hard disk

runs the more it heats up, so ventilation is important when you install disks internally

or in external enclosures.

Note: Removable media drives such as Jaz, Zip, and CD-RW drives are not suitable for

video capture and playback because of their low data transfer rates.

Determining How Much Space You Need

The amount of disk space you need depends on the specifications of the video format

you are using for editing. In some cases, you can capture video at a lower quality

(which saves disk space) for rough editing and then recapture only what you need at

higher quality to create the finished movie. This process is known as offline/online

editing. For more information, see Volume IV, Chapter 5, “Offline and Online Editing.”

Know Your Shooting Ratio

Remember that when you start editing a movie, you need to capture much more

media than you will use in the final movie. The ratio between the amount of footage

you begin with and the final duration of the movie is called the shooting ratio. When

you are estimating how much disk space you need for a project, calculate it based on

the total amount of media you plan to capture and use during editing, not the

intended duration of the final movie.

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Apple Final Cut Pro 5 User Manual Page 182