4.5

76Compressor User Guide
Audio properties
• Enable audio pass-through: Select this checkbox to copy the source audio unmodified
to the destination file. When this checkbox is selected, all the other settings in the
Audio Properties area are disabled.
• Channel layout: Use the pop-up menu to set the audio 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 the pop-up menu to manually set the sample size of the audio signal.
• Codec: You can add an audio codec that you’ve installed on your system to customize
the Compressor setting. To manually change the codec used in your setting, use this
pop-up menu. After you click OK and close the window, the setting’s audio properties
are updated to show your changes.
• Sample format: If you have selected Linear PCM as an audio codec, use this pop-up
menu to select whether to output your audio in Big Endian or Little Endian format.
• Quality: If you have selected AAC, FLAC, MPEG-4 HE AAC, MPEG-4 HE AAC V2, or Opus
as an audio codec, use this pop-up menu to select the quality of the audio output.
• Bit rate: If you have selected AAC as an audio codec, use this pop-up menu to set the
bit rate for the encoded audio.
• Bit rate strategy: If you have selected AAC, FLAC, MPEG-4 HE AAC, MPEG-4 HE AAC V2,
or Opus as an audio codec, 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.
• Include Lt Rt downmix track: Select this checkbox (available only when “Channel layout”
is set to more than two tracks) to add an additional stereo track to the transcoded
file that includes a stereo-mix version of the audio with the encoded surround
information included.
Audio effects
For a list of available audio effects in Compressor, and instructions on how to add an audio
effect to a setting, see Add and remove effects in Compressor.