Dolby Laboratories P/N 91659 - Manual (Page 23)

DolbyRemote Installation and Operation Dolby Digital Parameters
4-7
4.2.2 Surround Channel Processing
90 Degree Phase Shift
90 Degree Phase Shift controls whether or not a 90-degree phase shift is applied to
the surround channel(s) before the Dolby Digital encoding process. Its use enables
decoders to create a Dolby Surround compatible two-channel downmix. This
parameter is disabled if the encoding mode does not include any surround channels.
This parameter is not available on the DP567.
3 dB Attenuation
3 dB Attenuation controls whether or not the surround channel(s) are attenuated by 3
dB before the Dolby Digital encoding process. This allows material mixed in a room
calibrated film style (left and right surround channels are calibrated –3dB with respect
to the front channels) to be converted to video style calibration (all channels are
calibrated to the same level) by attenuating the surround channel(s) by 3 dB. This
parameter is disabled if the encoding mode does not include any surround channels.
This parameter is not available on the DP567.
4.2.3 Dynamic Range Compression
Dolby Digital has the ability to transmit full dynamic range audio for some listeners
as well as additional information which instructs a decoder on how to reduce the
dynamic range for others. For example, some people will want a reduced dynamic
range for late night listening, or because they have a smaller replay system. The
choice of Compression Characteristic and Dialog Normalization parameters as
well as the program material control the generation of this extra data.
Compression Characteristic
Compression Characteristic selectsthe compression characteristic that will be
applied to the encoded Dolby Digital bitstream. The encoder includes six dynamic
range compression modes that correspond to commonly used compression settings.
Any mode can be selected at any time. The compression modes apply only to the
encoded signal and are not applicable when the Pass Through mode is active. When
in the 1+1 Channel Mode, the selected Dynamic Range Compression applies to
both mono channels. The actual compression applied to each channel, in this case, is
independent, however they share the same compressor characteristics.
RF Overmodulation Protection
RF Overmodulation Protection controls whether or not the Dolby Digital signal is
protected against overmodulation distortion when decoded in RF compression mode
and subsequently modulated onto an RF carrier. Typical applications include digital
television set-top box systems in which decoded audio and video are combined into a
composite RF output signal. Note that this parameter has no effect on Line Out or