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183Compressor User Guide
batch In Compressor, one or more jobs to be processed. All jobs contained within the
batch (shown in the batch area of the Compressor window) are submitted collectively
when you begin the transcoding process. There are two types of batches in Compressor:
standard batches, used for most transcoding jobs, and iTunes Store packages, a special
workflow for submitting content to the iTunes Store.
bit rate The number of bits per second in the transmission of a digital video or audio
signal. The higher you set the bit rate, the better the quality of the output file. However,
higher bit rates require larger file sizes.
CAF (Core Audio Format) Apple’s Core Audio Format is a flexible file format for storing
and manipulating digital audio data. CAF provides high performance and flexibility, and is
scalable to future ultra high-resolution audio recording, editing, and playback.
captions In Compressor, onscreen text synchronized to the audio or video of a video
program. Compressor supports three industry-standard caption formats: CEA-608 closed
captions, iTT (iTunes Timed Text) subtitles, and SRT (SubRip Text) subtitles.
CEA-608 closed captions An industry-standard format for delivering onscreen text
synchronized to the audio or video of a video program. Originally developed for people
who are deaf or hard of hearing, CEA-608 closed captions (also known as Line 21 text) are
frequently used on televisions in loud environments (such as bars and airports). CEA-608
closed captions, which use the .scc filename extension, offer numerous formatting options.
Viewers can turn closed captions on or off while watching television shows, movies, web
videos, and other programs. In Compressor, CEA-608 closed captions are compatible with
iTunes Store packages and many transcode settings.
codec Short for COmpression/DECompression. A software component used to translate
video or audio from its current form to a different, digitally compressed form. A codec
encodes a data stream or signal for transmission, storage or encryption, or decodes it for
playback or editing. A similar term, encoder, is used to describe hardware that performs
the same activity.
color space The range of colors available for an image, sometimes called gamut. A wider
gamut allows for more possible color values and permits more accurate representation
of color.
delivery partner A content aggregator or encoding house certified by the iTunes Store
and authorized to submit iTunes Store packages to the store for sale. These partners
ensure your content is properly configured and formatted to meet the stringent submission
requirements of the iTunes Store. They can also provide billing and support services after
your video becomes available for sale.
descriptive audio An alternative audio track in an iTunes Store package that includes
voice narration to help visually impaired consumers understand what’s happening
onscreen. Descriptive audio narration is usually delivered during the natural pauses in
dialog or between critical sound elements. An iTunes Store package can contain multiple
descriptive audio tracks (in multiple languages, for example).
destination In Compressor, a group of one or more transcode settings plus a post-
transcoding action. If you use a destination to transcode a file, one or more new files are
created to the setting’s specifications and then an action is automatically performed on
the transcoded file. For example, the Add to TV Home Videos destination creates a file
optimized for viewing on Apple TV. After the file is processed, the Add to TV Home Videos
action automatically copies the output file to your Home Videos library on Apple TV.