Codecs Supported in QuickTime
Because the QuickTime file format is so flexible, practically any kind of media can be
stored in a track of its kind. However, in order to play back media stored in a track, the
QuickTime framework installed on your computer must be able to recognize the type
of compression (codec) used to encode the data.
Compression is necessary for video and audio storage on computers because the data
rates would otherwise be prohibitively high. And no matter how large computer
storage devices become, compression is still desirable because it means faster transfer
time and storing more information with less data.
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The QuickTime framework libraries support a remarkable number of video and audio
codec (compressor/decompressor) algorithms. The QuickTime frameworks are extensible,
so if a company invents a codec, the company can provide a QuickTime codec to support
it. Thus, if the media in a QuickTime file is not playing back because the format or codec
of the media is not recognized, you may be able to download and install it.
The QuickTime framework supports codecs that are commonly used today as well as
codecs that were once popular. When you go to export a QuickTime movie file, the
long list of available codecs demonstrates how extensive QuickTime codec support is.
At the same time, this list can be potentially daunting. Look for the codec you need and
ignore the rest.
Understanding Codec and File Format Naming Conventions
The distinction between file formats and codecs is often confused by shared naming
conventions. For example, MPEG-2 defines both a file format (a structure for organizing
video and audio data within media tracks) and a codec (an algorithm for encoding and
decoding video and audio data for the purposes of compression).
The following codec and file format examples may help to clarify the distinction.
 TIFF: This refers to a graphics file format. TIFF files may or may not use a codec, or
type of compression called LZW compression.
 JPEG: This is a type of compression that can be used on any still images or individual
video frames. Images encoded with JPEG compression can be stored in the JPEG file
format. QuickTime can open files in the JPEG file format as well as decode images
compressed with the JPEG codec.