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Linear Acoustic AERO.one V3 User Guide
3.6.3
Dynamic Range Control
Dynamic range control profiles can be selected in the Dolby Digital (AC-3) encoder.
NOTE: Dialogue Level must be set correctly for the DRC profiles to operate correctly.
When using an AERO.one preset such as TV 5B Gen or Light (Television 5-Band General
or Light), we suggest using is the Film Standard or Film Light DRC profile in the Dolby
Digital encoder for both Line Mode and RF Mode. This allows consumers to restore some
of the dynamic range. The AERO.one will still react to badly mismatched loudness levels,
but will do so in combination with the DRC profile in the Dolby Digital encoder.
We strongly recommend using the minimum degree of dynamic range processing required.
TV 5B Gen should provide more than enough pre-processing, and TV 5B Light might be
better suited for some material. In this way, the system can balance between permanent
changes to the input audio and metadata-based changes generated by the internal Dolby
Digital (AC-3) encoder. Of course for proper operation this method requires program-
ming that has been correctly produced.
AC-3 Encoder Metadata Value List
Specific audio metadata parameters that should be set in the AC-3 encoder are:
•
Data rate: 384kbps minimum, 448kbps preferred for 5.1 channels
•
Dialogue Level: -24 (with the AERO.one in TV 5B Gen)
•
Channel Mode (acmod): 3/2L
•
Line Mode Profile: Film Standard or Film Light
•
RF Mode Profile: Film Standard or Film Light
Other parameters are set to default values and will be adjustable in the future.
General Dolby Digital (AC-3) Encoder Setup
Note that when feeding video encoders such as those from Tandberg, an AES reference
signal is supplied by the video encoder specifically for feeding back to the AC-3 encoder. If the
encoder requires this, as the Tandberg models do, it must be used. It seems that this special
reference signal is derived from a 27MHz clock that is internal to the video encoder that
may or may not be referenced to the plant. Failure to use this reference may cause PTS
values to drift when observed on a transport stream monitor, and can cause audible glitch-
es when buffer over or underflow results.
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Applications
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