4.5

41Compressor User Guide
• Surround EX Mode: When using a 5.1 (L R C LFE Ls Rs), 5.0 (L R C Ls Rs), 4.1 (L R LFE
Ls Rs), or 4.0 (L R Ls Rs) layout, this property tells the playback device whether the
audio has been encoded in Dolby Digital Surround EX. 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 Digital Surround EX.
• Not Encoded: Tells the playback device that the bitstream was not encoded in Dolby
Digital Surround EX.
• Surround Encoded: Tells the playback device that the bitstream was encoded in
Dolby Digital Surround EX.
• Stereo downmix: Use this pop-up menu to set how to downmix a surround signal to a
stereo signal. See Audio channel layouts in Compressor.
Important: The LFE signal may be discarded by the Dolby Digital downmix process.
• Lo/Ro center, Lo/Ro surround, Lt/Rt center, Lt/Rt surround (for surround sound output):
Use these pop-up menus to set the decibel level at which the surround and center
channels are downmixed. Properties are enabled or disabled based on the channel
layout you choose.
• DRC line mode: Use this pop-up menu to set the dynamic range compression-
processing mode. The default setting, Film Standard, is recommended for all use cases.
• DRC RF mode: Use this pop-up menu to set the dynamic range compression-processing
mode for RF devices (TV sets, cable set top boxes, or other devices that have
RF connections).
• LFE low-pass filter: Select this checkbox to apply a 120 Hz low-pass filter to the
low-frequency effects (LFE) channel during output.
• DC filter: Select this checkbox to apply a DC (direct current) high-pass filter to all input
channels. Although this filter provides a simple way to remove DC offsets, note that
most mixed audio material is already free of DC offsets.
• Surround channels: 90 phase-shift: This checkbox, which applies a 90-degree phase
shift to the surround channels, is selected by default. The shift in phase decorrelates
the front and back channels and prevents the L and Ls signals from canceling each
other out if a surround-compatible downmix is later applied to the decoded signal.
• Surround channels: 3dB attenuation: Select this checkbox to apply a 3 dB cut to the
surround channels during output. This option is intended for multichannel output (like a
film soundtrack) that is being transferred to a consumer home theater format. Cinema
surround channels are mixed 3 dB “hot” (higher) relative to the front channels to
account for cinema amplifier gains.
• Dialog normalization: Enter a value in the field to set the loudness of the program in
your sound files relative to full modulation. The playback device uses this information
to maintain similar loudness among different AC-3 streams. The goal is to give all
AC-3–encoded audio files the same listening level, regardless of the source file.
Audio effects
For a list of available audio effects and instructions on how to add an audio effect to a
setting, see Add and remove effects in Compressor.