Apple Final Cut Pro 6 User Manual
Page 1716
Chapter 16
Learning About QuickTime
233
III
Uncompressed movies can have an alpha channel. Alpha channels define levels of
transparency in your movie and are useful if you’re delivering an effects shot for use in
someone else’s composition. For more information on alpha channels, see Volume III,
Chapter 19, “Compositing and Layering.”
Animation
The Animation codec was developed for computer-generated imagery, which often has
large areas of uniform color and little, if any, noise. It is a lossless codec, which means it
doesn’t degrade quality or add artifacts to your video when it applies compression. For
more information, see “
Video footage, which generally has more grain, noise, and variations of texture and
color than animated material, may not be compressed as much with the Animation
codec as with other methods. Because some lossless compression is better than none,
this codec is used more frequently than Uncompressed.
Note: Animation movies will not play back in real time on most systems. Animation
movies can also have an alpha channel.
DV Codecs
QuickTime supports a wide range of DV codecs, including DV NTSC and DV PAL,
DVCPRO 50, and DVCPRO HD. This allows you to natively capture, edit, and playback
footage from DV camcorders without first transcoding to another format.
Apple M-JPEG
There are two Apple M-JPEG codecs, M-JPEG A and M-JPEG B. These are variable data
rate codecs similar to the ones used by video capture cards. If you need to deliver more
heavily compressed material to keep files small, consider these codecs. M-JPEG is a
“lossy” codec (meaning visual information is permanently removed from the video
frames) and will result in artifacts in your video. The severity of these artifacts depends
on the data rate you choose.
Several video interface cards on the market can play back either M-JPEG A or M-JPEG B
in real time without rerendering the material, or, at most, doing minimal rerendering.
This makes file interchange very fast. Before you use either M-JPEG A or B, consult the
manufacturer of the capture card you’re using to find out which one you should use.
Note: Apple M-JPEG movies cannot have alpha channels.
JPEG
JPEG is similar to M-JPEG, except that the compression artifacts can be less severe at
similar data rates. JPEG movies may play back in real time on your system, depending
on your system’s capabilities and the data rate of the movie.
Note: JPEG movies cannot have alpha channels.