4.1

Chapter 4 Advanced adjustments 43
Retiming
This section contains one property:
•
Set duration to: Sets the processing algorithm used to adjust the frame rate during transcoding.
Select one of the following options:
•
[Percentage] of source: Modies the output clip’s speed by a percentage of the source clip’s
speed. Enter a value in the percentage eld or choose a preset value from the adjacent
pop-up menu (with a downward arrow).
•
[Total duration]: Sets the duration of the clip. Enter a timecode duration in the eld or click
the arrows to increase or decrease the time.
•
So source frames play at [frame rate] fps: Nondestructively changes the playback speed of the
clip, without discarding frames or creating new frames. This setting has no eect unless the
“Frame rate” value in the Video inspector is dierent than the source le’s frame rate. For
example, if you add a 10-second source le with a frame rate of 24 fps to Compressor, set the
“Frame rate” property in the Video inspector to 25 fps, and then select “So source frames play
at 25 fps” in the General inspector, the duration of the transcoded clip (at 25 fps) is 9 seconds
and 15 frames.
Note: This option is not available when outputting an MPEG-4 audio le.
For more information, see Retime video and audio output on page 71.
Video properties
•
Frame size: Use the pop-up menu to set the frame size (resolution) for the output le.
•
Pixel aspect ratio: Use the pop-up menu to set the pixel aspect ratio (the ratio between the
image frame width and height). You can also modify the aspect ratio of the output le using
cropping and padding properties. For more information, see Modify frame size overview on
page 69.
•
Frame rate: Use this pop-up menu to set the playback rate (the number of images displayed
per second) for the output le. For more information, see Frame rate options overview on
page 71.
•
Field order: Use the pop-up menu to set the output scanning method (either the eld
dominance or a conversion to progressive scanning). There are four options:
•
Same as Source: Maintains the same scanning method used by the source media le.
•
Progressive: Scans complete frames (not frames divided into interlaced elds).
•
Top First: Scans interlaced elds, giving dominance (eld order) to the top eld, also known
as eld two, the upper eld, or the odd eld.
•
Bottom First: Scans interlaced elds, giving dominance (eld order) to the bottom eld, also
known as eld one, the lower eld, or the even eld.
•
H.264 prole: Use the pop-up menu to set the video compression for the output le. There are
three options:
•
High: Provides high quality output.
Note: This setting is not compatible with older MPEG-4 Part 10 devices.
•
Main: Similar to the Baseline prole, with additional support for standard-denition (SD)
video requirements.
•
Baseline: Primarily for video conferencing and mobile applications.
•
Entropy mode: Use the pop-up menu to set the entropy mode to CABAC, which provides
higher-quality output, or CAVLC, which is faster.
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