4.5

135Compressor User Guide
Modify playback speed
Retiming options in Compressor
There are two ways to use Compressor to modify the rate at which a transcoded file plays
back. You can apply speed effects to slow down or speed up playback, or you can change
the frame rate of the transcoded file (which may or may not have an effect on playback
speed). If you do change the frame rate of the output file, there are special options for
working with interlaced footage, including deinterlacing and reverse telecine.
The controls that make speed modifications are located in the General inspector and in the
Video inspector.
Retime video and audio using Compressor
To retime video using Compressor, you make changes to properties in both the General
inspector and the Video inspector. (You can create some effects by modifying properties
in only one of the inspectors.)
The Retiming section in the General inspector allows you to define a new speed setting
for the clip. You can specify a percentage, such as 50% to create a slow-motion effect,
or 200% to create a fast-motion effect. You can identify a precise number of frames and
allow the software to calculate the percentage for you; or you can instruct Compressor to
renumber the current frames into a different frame rate in order to convert a file from one
frame rate to another without adding or deleting any frames.
In the Video Properties section of the Video inspector, you can set a specific frame rate for
the transcoded file. By default, this property is set to Automatic, which applies the frame
rate of the source file to the output file.
If the source media file contains audio, retiming modifies the audio speed as well, thereby
keeping audio and video in sync. Compressor also automatically corrects the pitch so the
audio doesn’t sound artificially high or low.
Important: If you modify retiming properties in a setting that uses the QuickTime Movie
format and choose “Copy audio tracks from source” in the Audio inspector, the audio
speed is not changed. Consequently, audio in the output file will not maintain sync with
the video.
In the Quality section of the Video inspector you can set the retiming quality to specify the
processing method used when you make changes to other settings that modify the speed
or frame rate of a clip.
Modify timing and frame rate in Compressor
In Compressor, you can modify the duration of a transcoded file by adjusting controls in
the General inspector. You can modify the frame rate of a transcoded file by adjusting
controls in the Video inspector.