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Linear Acoustic LA-5180 Metadata Frame Sync/Generator Operation Manual
operating modes are known as Line Mode and RF Mode due to the type of output they are
typically associated with. Line Mode is typically used on decoders with six- or two-channel
line-level outputs and RF Mode is used on decoders that have an RF-remodulated output.
Full-featured decoders allow the consumer to select whether to use DRC and if so, which
operating mode to use. The consumer sees options such as Off, Light Compression, and
Heavy Compression instead of None, Line Mode, and RF Mode. Advanced decoders may
also allow custom scaling of the DRC metadata.
All that needs to be done during encoding is selection of the dynamic range control profiles
for Line Mode and RF Mode. The profiles are described in the following sections.
Note:While the use of DRC modes during decoding is a consumer-selectable feature, the
dialogue level parameter setting is not. Therefore, the proper setting of the dialogue level
parameter is essential before selecting a DRC profile.
Line Mode (dynrg)
Line Mode offers these features:
•
Low-level boost compression scaling is allowed.
•
High-level cut compression scaling is allowed when not downmixing.
•
Dialogue, as set by the dialogue level parameter, is reproduced at a constant level of -
31 dBFS LAeq.
All line-level or power-amplified outputs from two-channel set-top decoders, stereo digital
televisions, 5.1-channel digital televisions, and A/V surround receivers use Line mode.
Consumer control of the dynamic range is limited when downmixing. Products with stereo
or mono outputs do not usually allow consumer scaling of Line Mode. This is because
these devices are usually downmixing, (for example, when receiving a 5.1-channel signal.)
However, in these products the consumer may have a choice between Line Mode and RF
Mode.
RF Mode (compr)
RF Mode offers these features:
•
High- and low-level compression scaling is not allowed (when active, fully applied).
•
+11 dB gain shift raises overall program level.
•
Dialogue, as set by the dialogue level parameter and combined with the +11 dB gain
shift, is reproduced at a constant level of -20 dBFS LAeq.
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