4.5

186Compressor User Guide
lower third A television industry term for a graphic placed in the lower area of the screen,
usually to convey details about subjects or products. A common use of lower thirds is to
identify individuals on the screen with their names and job titles.
marker A marker flags a specific timing location in a source file. You can append a marker
with editing notes or other descriptive information. Additionally, when you output the
source file to an H.264, MPEG-2, or MPEG-4 video format, each marker forces the creation
of an I-frame. Added I-frames improve compression quality, but can increase overall file
size. Compressor can create the following types of markers:
• Chapter markers: Generate named index points and thumbnail images for DVDs,
QuickTime movies, or video podcasts. You can also assign a URL to a chapter marker to
have that URL appear during playback of a podcast. Chapter markers are also included
in submissions to the iTunes Store as part of an iTunes Store package. Chapter markers
appear orange in the Compressor preview area.
• Compression markers: Generate an I-frame, but do not generate thumbnails, chapter-
track entries, or other metadata. Add them to a video if a section appears to have lower
image quality than the surrounding frames. Compression markers appear blue in the
Compressor preview area.
• Edit markers: Function identically to compression markers. They are commonly used by
compression artists to force an I-frame at an edit point to ensure higher image quality
at that moment in the video. Edit markers appear red in the Compressor preview area.
• Podcast markers: Like chapter markers, podcast markers can have artwork and a URL
assigned to them. Podcast markers are usually used to provide a slideshow (with URLs)
for users to view when playing audio podcasts. However, podcast marker names do
not appear in the slideshow, and users cannot navigate to a podcast marker in the
transcoded file. Podcast markers appear purple in the Compressor preview area.
matrix stereo A stereo downmix of a surround track for playback on a device with only two
speakers; matrix stereo can also be decoded to play the full surround mix on a surround-
capable playback device.
MP3 Refers to the MPEG-1 or MPEG-2 Audio Layer 3 compression standard and file format.
Like AAC, MP3 uses perceptual audio coding and psychoacoustic compression to remove
superfluous information that the human ear doesn’t hear.
nit A unit of measure describing the luminance (light intensity) of a video display. One nit
is equal to one candela per square meter.
output row In Compressor, an output row in a job contains the instructions used for
transcoding a source media file. An output row includes a setting (shown on the left) that
specifies properties defining how to transcode the source media file, a location (shown in
the middle) where the transcoded file will be saved, and a filename (shown on the right) for
the transcoded file.
P3 D65 Also known as Display P3, a wide-gamut color space based on the DCI-P3 color
standard developed for digital movie projection. P3 D65 is the display color space of
recent Apple devices, including the iMac (with Retina 4K or 5K display), MacBook Pro, and
iPad Pro.