4.5

40Compressor User Guide
• 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.
Note: All files intended for video and audio DVD authoring must have a 48 kHz sample
rate as required by the DVD specification.
• Target system: Use this pop-up menu to identify the system on which you are going
to play the output file. Compressor limits options in other related properties to those
appropriate for the target system.
• DVD Video: Choose this option if you’re encoding for use in a DVD video authoring
application.
• DVD Audio: Choose this option if you’re encoding for use in a DVD audio authoring
application.
• Generic AC-3: Choose this option to remove the target system setting limit (the most
generic choice).
• Data rate: Use this pop-up menu to set the number of kilobits per second (kbps)
required to deliver your audio file. Using a higher rate produces a higher-quality
audio file.
Tip: For stereo encoding, rates of 192 kbps and 224 kbps are typical and
will produce good results. For Dolby Digital 5.1 encoding, a rate of 384 kbps is
recommended. For Dolby Digital Plus encoding, a rate of 192 kbps is recommended.
• Bit stream mode: Use this pop-up menu to define the audio service contained within
the Dolby Digital or Dolby Digital Plus bitstream.
• Surround mode: When using a Mono or Stereo (L R) channel layout, this property tells
the playback device whether the two-channel encoded bitstream contains a Dolby
Surround (Lt/Rt) program that requires Dolby Pro Logic decoding. Choose an option
from the pop-up menu:
• Not Indicated: Does not send the playback device information about whether the
bitstream was encoded in Dolby Surround.
• Not Encoded: Tells the playback device that the bitstream contains information not
encoded in Dolby Surround.
• Surround Encoded: Tells the playback device that the bitstream contains information
encoded in Dolby Surround.