Monitor Dolby-B
ased Surround Sound
Usage Notes
Your instrument determines the downmix based on several parameters within the Dolby m etadata and the Dolby
downmix selection. For e xample, if the Dolby Audio Status screen shows E xtended Bitstream information indicating that
the preferred downmix is Lt/Rt, the center channel is attenuated by -3dB and the surround channels are attenuated by
-6dB before they are combined into the stereo downmix.
The listening modes can be used to monitor any multichannel Dolby Digital audio program with a user-selectable
number of channels. You can select among several basic and Pro Logic listening modes, the descriptions of which
follow. Depending on the Channel Mode, these listening modes affect the content displayed on the Audio Display level
bars. (See Table 1 on page 103.)
Basic Listening Modes
EX. Use EX if the two surround channels have been matrix encoded with a back channel. If the EX listening mode is
selected and there are two surround channels present, the bar display will add two back channels, Lb and Rb, to create a
7.1 channel display.
Full. Full does not modify the number of channels indicated by the channel mode in either the display or the outputs.
3Stereo. Use 3 Stereo to m onitor the Dolby Digital signal with only the left, center, and right channels. In this mode, if
there are surround chann
els present, they are mixed into the left and right channels with the surround mix level attenuation.
Phantom. When using Phantom, the center channel, if present, gets attenuated with the center mix level value and is
then added into the left and right channels.
Stereo. Stereo always creates a Lo/Ro downmix using the center and surround mix levels contained in the metadata.
The Lfe is disabled.
Mono. Mono mode will always mix down to a single center channel, usually by creating a Lo/Ro downmix and adding Lo to
Ro. The Lfe is disabled.
Pro Logic Listening Modes
Pro Logic listening modes perform different functions depending on what the source material is. If the source is a Dolby
Digital stream with three or more channels, then a surround compatible
Lt/Rt downmix is created and then decoded into a
selectable number of channels. If the source is a 2/0 Dolby D igital stream, then these P ro Logic modes will do a Pro Logic
decode to produce the number of channels requested by the listening mode. If the source is PCM, then a full Pro Logic
decode is provided regardless of the specific Pro Logic mode selected.
Pro Logic Full. Pro Logic Full will create a Lt/Rt downmix of any input with three or more channels. This Lt/Rt downmix
will then be Pro Logic decoded to produce a LCRS output w here the surround channel is reduced 3dB and reproduced in
both the Ls and Rs bars.
A 2/0 encoded Dolby stream will be assumed to be Pro Logic encoded already and will be Pro Logic decoded to produce a
LCRS output. Again, the s urround channel is reduced 3dB and reproduced in both the Ls and Rs bars.
Any PCM input will be decoded the same as a 2/0 Dolby Digital input.
Pro Logic 3 Stereo. Pro Logic 3 Stereo will create a Lt/Rt downmix of any input with three or more channels. This Lt/Rt
downmix will then use Pro Logic decoding to produce a center channel and provide LCR bars.
A 2/0 encoded Dolby stream will be assumed to be Pro Logic encoded already and will be Pro Logic decoded to produce a
LCR output.
102 Waveform Rasterizers Quick Start User Manual
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