GUIDE TO INSTALLATION AND OPERATION
36
| XVP-1801
Downmix
tab
This tab provides resources to control the downmix
of a “5.1 channel” surround-sound audio signal into
an LtRt or LoRo stereo pair. The 5.1 terminology
refers to six discrete audio channels, with the low
frequency effect (LFE) channel of limited bandwidth
designated as the .1 channel. The downmix can be
done using any of the 16 audio channels processed
by the audio processor using the Input Channels
controls in the interface.
Input Channels area:
Use the 6 pulldowns to select
the source channels for the downmix process.
Output Channels area:
The downmix stereo pair
output can be mapped to either channels 7&8 or
15&16, selected from the pulldown. The pulldown is
labeled according to the Mode selection made in the Downmix area.
Downmix area:
Mode:
this pulldown menu selects the downmix mode:
•
OFF:
disables the audio downmix. Audio channels 7 and 8 or 15 and 16 pass through unchanged.
•
LtRt:
enables the downmix of 5.1 channels into an LtRt matrix surround encoded stereo pair. The
input signals on channels 7 and 8 or 15 and 16 are discarded.
•
LoRo: enables the downmix of 5.1 channels into an LoRo stereo pair, which is a conventional stereo
signal. The input signals on channels 7 and 8 or 15 and 16 are discarded.
Levels:
This pulldown selects the downmix levels mode:
•
AUTO:
the Center and Surround downmix levels and the dialogue normalization (dialnorm) level are
taken from the Dolby metadata embedded in the video input, when present. If no Dolby
metadata is present, the downmix levels default to those currently set by the user in the
Center and Surround pulldowns. The LFE downmix level is taken from the LFE pulldown.
•
MANUAL: the user sets the downmix levels via the CENTER, SURROUND and LFE pulldowns:
◊
CENTER – sets the center channel downmix level to the selected value
[+3 dB, +1.5dB, 0 dB, -1.5 dB, -3 dB, -4.5 dB, -6 dB, mute]
◊
SURROUND – sets the surround channels (Ls & Rs) downmix level to the selected value
[+3 dB, +1.5dB, 0 dB, -1.5 dB, -3 dB, -4.5 dB, -6 dB, mute]
◊
LFE – sets the LFE channels downmix level to the selected value. The LFE downmix value is used
in both Auto and Manual modes.
[+10 dB, +9 dB, +7.5, +6 dB, +4.5 dB, +3 dB, +1.5dB, 0 dB, -1.5 dB, -3 dB, -4.5 dB, -6 dB,
mute]
The block diagrams below shows the configuration of the LtRt surround sound downmixer and the LoRo
stereo downmixer.
Figure 3.20
Audio Processing group – Downmix tab