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.
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Chapter 21
Creating QuickTime Movie Output Files
• Lossy codecs: In comparison to lossless codecs, lossy codecs return only an approximation
of the data and are usually used to deliver finalized video to an end user. The level of
approximation is determined by the quality of the codec. Typically there is a tradeoff
between the output quality of the codec and its achievable level of compression. With
some codecs, a compression ratio of at least 5:1 can be reached without visible
degradation. An example of a lossy codec is the Photo-JPEG codec.
Low-quality lossy compression introduces unnatural visual artifacts that may become
noticeable to the human eye. Using a lossy codec, you should compress your media
file only once, because compressing a file multiple times adds more artifacts.