4.2

iTunes Store Package Publishers who submit videos to the
iTunes Store must deliver their content in a carefully prescribed
format called an iTunes Store package. Compressor can create
these packages, provided you have all the requisite components
(video files, audio files, subtitle files, closed-caption files, and so
on).
iTT subtitle format The iTT (iTunes timed text) file format is a
subset of the Timed Text Markup Language, Version 1.0
(TTML) from the
(W3C). All iTT documents are TTML
documents that use a restricted subset of TTML. In addition to
providing text and timing, an iTT document specifies the font style,
font color, text alignment, and layout of the timed text.
Job In Compressor, the source media file and output instructions
(one or more output rows, each containing a setting, location, and
file name), ready to be transcoded.
Job action In Compressor, an action that is performed on a
media file after it is transcoded. For example, a job action can
add a transcoded file to iTunes or publish a transcoded file to a
popular video-sharing website like YouTube.
Key frame interval A key frame is a frame that stores a complete
image. Key frames provide the entire image in the video stream;
after that image is provided, incremental changes between related
frames are stored (not the entire image). Thus, when the image in
the video changes dramatically, for example, when switching
between images, a keyframe must be created to mark the
location of change. It’s recommended that you allow Compressor
to determine the key frame interval for your output file; however,
you can also set the key frame interval manually.
W3C
Candidate Recommendation 23 February 2010
World Wide Web Consortium