Dolby Laboratories DP564 - Manual (Page 88)

DP564 Multichannel Audio Decoder Appendix A: Metadata
A-18
Note: The parameters DC Filter, Lowpass Filter, LFE Lowpass Filter, Surround
3 dB Attenuation, and Surround Phase Shift appear after the Extended BSI
parameters on Dolby E and Dolby Digital equipment menus.
DC Filter
This parameter determines whether a DC blocking 3 Hz highpass filter is applied to
the main input channels of a Dolby Digital encoder prior to encoding. This parameter
is not carried to the consumer decoder. It is used to remove DC offsets in the program
audio and would only be switched off in exceptional circumstances.
DC Filter Setting
Enable
Disable
Lowpass Filter
This parameter determines whether a lowpass filter is applied to the main input
channels of a Dolby Digital encoder prior to encoding. This filter removes high-
frequency signals that are not encoded. At the suitable data rates this filter operates
above 20 kHz. In all cases it prevents aliasing on decoding and is normally switched
on. This parameter is not passed to the consumer decoder.
Lowpass Filter Setting
Enable
Disable
LFE Lowpass Filter
This parameter determines whether a 120 Hz 8 th order lowpass filter is applied to the
LFE channel input of a Dolby Digital encoder prior to encoding. It is ignored if the
LFE channel is disabled. This parameter is not sent to the consumer decoder. The
filter removes frequencies above 120 Hz that would cause aliasing when decoded.
This filter should only be switched off if the audio to be encoded is known to have no
signal above 120 Hz.
LFE Lowpass Filter Setting
Enable
Disable