Apple Compressor 3 - Manual (Page 246)

Understanding Codecs
Codec stands for compressor (CO)/decompressor (DEC) pairs. You use different codecs for
different playback methods (such as the web or DVD). Once you know the playback
method of your target audience, you can pick a suitable codec. To decide which codec
is right for your needs, you must choose the necessary level of compression to meet your
data rate limits and the level of quality you want.
The following sections discuss issues to be aware of when selecting a video or audio
codec.
QuickTime Video Codecs
Each codec offers advantages and disadvantages. Some are more appropriate for storing
certain types of media; others introduce more artifacts. Some compress slowly and
decompress quickly, while others compress and decompress at the same speed. Some
codecs can compress a file to 1/100 of its original size, while others decrease the file size
very little. Some codecs are available only on specific operating system platforms, some
require a particular processor, and some require a minimum version of QuickTime for
playback.
When choosing a codec you should consider the following:
• Minimum system requirements of your target audience
• Source material
• Quality of the compressed media file
• Size of the compressed media file
• Compression/decompression time for the media file
• If the media file will be streamed
Compressor comes equipped with the standard video codecs that QuickTime offers and
the additional codec options that come with QuickTime Pro. Unless you know that people
in your target audience have a particular codec installed on their computers, you should
use one of the standard QuickTime codecs to ensure universal conformity.
Note: See the relevant QuickTime documentation for more information about choosing
video codecs and how to get the best out of the video codec settings.
Video codecs can be divided into the following two types:
• Lossless codecs: Lossless codecs completely preserve the data they compress and are
usually used to transfer footage from one editing suite to another. Lossless codecs can
require high data rates and high-end computers with specialized hardware. Examples
of lossless codecs are the Animation, 8-bit, and 10-bit uncompressed 4:2:2 codecs.
246 Chapter 20 Creating QuickTime Movie Output Files