4.1

Chapter 4 Advanced adjustments 44
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Key frame interval: Enter a value in the text eld to set the key frame interval (number of
frames) at which you want key frames created in your output le. Alternatively, you can select
Automatic to have Compressor choose the key frame interval rate (the displayed value is 0
with Automatic on; the actual value is determined during the encoding process).
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Data rate: Sets the number of kilobits per second (kbps) required to deliver your video le.
Drag the slider or enter a value in the eld. This setting is useful if you have a specic bit rate
(such as a DSL connection) or amount of space (on a DVD or CD- ROM).
Important: When you set a data rate, you override other codec quality properties because the
codec compresses the le as much as it needs to based on its data rate limit.
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Multi-pass: Select this checkbox to turn on multi-pass encoding that uses additional analysis
of video frames to produce a high-quality output le. For faster (single-pass) transcoding, turn
this feature o by deselecting the checkbox.
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Allow frame reordering: Select this checkbox to potentially provide a better-quality output le
by allowing Compressor to reorder video frames during transcoding.
Cropping and padding
Customize the nal cropping, sizing, and aspect ratio using the Cropping & Padding properties.
Cropping removes video content from an image. Padding scales the image to a smaller size while
retaining the output image’s frame size. For more information about these properties, see Modify
frame size overview on page 69.
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Cropping: This pop-up menu sets the dimension of the output image. The custom option
allows you to enter your own image dimensions in the elds; other options use predetermined
sizes. The Letterbox Area of Source option detects image edges and automatically enters crop
values to match them. This is useful if you want to crop out the letterbox area (the black bars
above and below a widescreen image) of a source media le.
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Padding: This pop-up menu sets the scaling of the output image while retaining the output
image’s frame size. The custom option allows you to enter your own scaling dimensions in the
elds; other options use predetermined dimensions.
Quality
The following properties determine how the video will be resized, retimed, and otherwise
adjusted when transcoded.
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Resize lter: This pop-up menu sets the resizing method. There are three options:
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Fast (Nearest Pixel): Provides the fastest processing time.
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Better (Linear Filter): Provides a medium trade-o between processing time and
output quality.
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Best (Statistical Prediction): Provides the highest output quality, but takes longer.
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Retiming Quality: This pop-up menu sets the retiming method. There are four options:
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Fast (Nearest Frame): Uses a copy of the nearest available frame to ll the new
in-between frames.
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Better (Motion Adaptive): Uses deinterlacing on areas of the source le that contain
movement to produce good-quality output.
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Best (Motion Compensated): Uses deinterlacing on areas of the source le that contain
movement to produce high-quality output.
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Reverse Telecine: Removes the extra elds added during the telecine process to convert the
lm’s 24 fps to NTSC’s 29.97 fps. Choosing this item disables all the other Quality controls. For
more information, see About reverse telecine on page 74.
67% resize factor