Model DP569 User’s Manual Metadata
A–18
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 default
Disable
LFE Lowpass Filter
This parameter determines whether a 120 Hz 8th 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 default
Disable
Surround 3 dB Attenuation
The Surround 3 dB Attenuation parameter determines whether the surround
channel(s) are attenuated 3 dB before encoding. The attenuation actually takes place
inside the Dolby Digital encoder. It balances the signal levels between theatrical
mixing rooms (dubbing stages) and consumer mixing rooms (DVD or TV studios).
Consumer mixing rooms are calibrated so that all five main channels are at the same
sound pressure level (SPL). For compatibility reasons with older film formats,
theatrical mixing rooms calibrate the surround channels 3 dB lower in SPL than the
front channels. The consequence is that signal levels on tape are 3 dB louder.
Therefore, to convert to a consumer mix from a theatrical calibration it is necessary to
reduce the surround levels by 3 dB by enabling this parameter.
Surround 3 dB
Attenuation Setting
Enable
Disable