4.5

38Compressor User Guide
• Default location: Choose an item from the pop-up menu to set the default save location
for transcoded files.
• File type: Choose a file type from the pop-up menu (AIFF, CAF, FLAC, or WAVE).
Retiming
Sets the processing algorithm used to adjust the frame rate during transcoding. Select one
of the following options:
• Set to percent of source using: Modifies the output clip’s speed by a percentage of the
source clip’s speed. Enter a value in the percentage field or choose a preset value from
the adjacent pop-up menu (with a down arrow).
• Set to: Sets the duration of the clip. Enter a timecode duration in the field 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 property has
no effect unless the “Frame rate” value in the Video inspector is different from the
source file’s frame rate. For example, if you add a 10-second source file 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
resulting duration of the transcoded clip (at 25 fps) will be 9 seconds and 15 frames.
For more information, see Retime video and audio using Compressor.
Audio properties
• Channel layout: Use this pop-up menu to manually set the type of audio channel
layout. For more information about audio channel layouts, including the surround sound
channel layout, see Audio channel layouts in Compressor.
• Sample rate: Use this pop-up menu to set the number of times per second that music
waveforms (samples) are captured digitally. The higher the sample rate, the higher the
audio quality and the larger the file size.
• Sample size: Use this pop-up menu to manually set the sample size of the audio signal.
• Format: Use this pop-up menu to set the format of the audio output.
• Quality: Use this pop-up menu to select the quality of the audio output.
• Bit rate: Use this pop-up menu to set the bit rate for the encoded audio.
• Bit rate strategy: Use this pop-up menu to select the strategy used to encode the audio.
There are four options:
• Constant bit rate: Uses the value set in “Bit rate” to determine the bit rate for the
encoded audio.
• Average bit rate: Uses the value set in “Bit rate” to determine the target average
bit rate for the encoded audio. This option provides a more consistent bit rate than
variable bit rate.
• Variable bit rate constrained: Uses the value set in “Bit rate” to determine the
maximum bit rate for the encoded audio.
• Variable bit rate: Encodes the audio using a variable bit rate determined by
Compressor.