PRELIMINARY DATA SHEET
MSP 34x2G
2.6. Surround Processing
2.6.1. Output Configuration
2.6.2. Surround Processing Mode
Surround sound processing is controlled by three func-
tions:
Like the MSP 34x1G ICs, the MSP 34x2G can be used
for virtual surround sound on the left and right loud-
speaker outputs. For multichannel outputs (more than
2 channels), extra output pins have been defined
(DACM_C and DACM_S pins). For processing of these
output channels, internal resources are shared with
the headphone processing. As a result, headphone
output is not possible together with multi-channel sur-
round processing. When headphone output pins are
active, the surround outputs are muted and vice versa.
There are two options: the HP/CS switch and the
channel configuration. The output configuration is con-
trolled by means of register 48hex on I2C subaddress
The "Decoder Matrix" defines which method should be
used to create a multichannel signal (L, C, R, S) out of
a stereo input.
The "Surround Reproduction" determines whether the
surround signal “S” is fed to surround speakers. If no
surround speaker is actually connected, it defines the
method that should be used to create surround effects.
The “Center Mode” determines how the center signal
“C” is to be processed. It can be left unmodified, dis-
tributed to left and right, discarded or high pass fil-
tered, whereby the low pass signals are distributed to
left and right.
12hex
.
2.6.1.1. HP/CS Switch
The surround processing mode is controlled by means
of register 4Bhex on I2C subaddress 12hex
.
This switch defines which output pin pair is driven by
the D/A converters that are used for headphone or sur-
round processing. The unselected pins are muted.
This makes it convenient to connect the center/sur-
round amplifiers or outputs to the MSP 34x2 without
external switches.
2.6.2.1. Decoder Matrix
The Decoder Matrix allows three settings:
– ADAPTIVE:
The adaptive matrix is used for Dolby Surround Pro
Logic. Even sound material not encoded in Dolby
Surround will produce good surround effects in this
mode. The use of the adaptive matrix requires a
license from Dolby Laboratories (See License
Notice on page 5).
Mute the Headphone/Surround channel by setting reg-
ister 06hex to 0000hex before switching. Allow at least
2 s for settling to avoid audible plops.
2.6.1.2. Channel Configuration
– PASSIVE:
The channel configuration defines whether surround
processing is switched on and what resources of the
IC are to be used for surround sound processing.
There are 3 options:
A simple fixed matrix is used for surround sound.
– EFFECT:
A fixed matrix that is used for mono sound and spe-
cial effects. In adaptive or passive mode no sur-
round signal is present in case of mono, moreover in
adaptive mode even the left and right output chan-
nels carry no signal (or just low frequency signals in
case of Center Mode = NORMAL). If surround
sound is still required for mono signals, the effect
mode can be used. This forces the surround chan-
nel to be active. The effect mode can be used
together with 3D-PANORAMA. The result will be a
pseudo stereo effect or a broadened stereo image
respectively.
– STEREO:
The IC is in the normal stereo processing mode. No
surround processing takes place. In this mode, the
IC is compatible to the MSP 34x0G.
– TWO_CHANNEL:
Surround sound processing is switched on, but only
left and right loudspeaker channels are used for out-
put. This mode is used for virtual surround sound.
– MULTI_CHANNEL:
Surround sound processing is switched on, left and
right loudspeaker channels together with left and
right headphone channels are used for output. The
following relationship applies: Center corresponds
to the left headphone channel; Surround corre-
sponds to the right headphone channel.
Micronas
15
MICRONAS [ MICRONAS ]
