Apple Compressor (4.1.2) - Manual (Page 27)

Chapter 4 Advanced adjustments 27
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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.
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DRC RF mode: Use this pop-up menu to set the dynamic range compression processing mode
for RF (TV sets, cable set top boxes, or other devices that have RF connections).
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LFE low-pass filter: Select this checkbox to apply a 120 Hz low-pass filter to the low-frequency
effects (LFE) channel during output.
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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.
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Surround channels: 90 phase-shift: This property, 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.
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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.
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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 on page 74.
H.264 for Apple Devices
The built-in Apple Devices settings use the H.264 for Apple Devices transcoding format. You can
also create custom settings that use the H.264 for Apple Devices transcoding format.
The properties of built-in and custom settings that use this transcoding format are located in the
General, Video, and Audio inspectors. These properties are described below.
Important: When you add a setting (or a destination that includes settings) to a job, Compressor
analyzes the source media and then automatically assigns the most appropriate setting
properties (based on the setting’s transcoding format and the characteristics of your source
media file). It’s recommended that you use the automatically assigned setting properties.
Setting summary
Displays the setting name and transcoding format, as well as an estimated output file size. When
you add a setting to a job or change the setting’s properties, this summary automatically updates.
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