Surrounder Explained

ROBSCIX · Sep 3, 2004, 10:34 PM

I found some people are unclear as to certain values in surrounder. I will explain these settings as I have come to understand them.
Speaker Mode: Set to speakers you have. e.g 2.0, 4.1, 5.1..etc.
Surround: On...Enables balancing of surround parameters.
Surround: Off...Disables surround sound.
Surround: Copy....Allow Rear front and rear channels to receive same signal.

VCenterA: The Amount of signal to the CENTER channel on a 5.1 system.
VRearA: The Amount of signal to the REAR channels.
VRearW: The Width of your REAR channels.
VRearD: The Amount of signal Delay between front and rear channels.

Use Subwoofer: Enables Discrete subwoofer output, if you have one.

Enable Bass Redirection: Enables crossover frequency adjustment for the subwoofer channel.

Split Freq: The Frequency (Hz) at which crossover starts to filter signals to subwoofer channel.

Change your settings to get best possible surround sound imaging. Use Bass Redirection and split freq to get the most natural sounding bass response. Of course you just set them to what sounds good on your system in your space to you.

Hope that helps.

**dj_stick** · Sep 4, 2004, 12:54 AM

you sound right, and yup sticky

Max M. · Sep 4, 2004, 05:19 AM

probably, you'll find following info to be useful too
(these are some details about first version of surrounder - written 25.02.03
- something may be changed since)

:

Code:

signal paths:

spk:2.1, sur:off
----------------------
L  -------> fL
R  -------> fR
fL -------> fL
fR -------> fR
sL -------> sL
sR -------> sR
sC -------> sC

spk:2.1, sur:copy
----------------------
L  -------> fL
R  -------> fR
fL -------> fL
fR -------> fR
sL -------> sL
   `------> fL
sR -------> sR
   `------> fR
sC -------> sC
   `------> fL
   `------> fR

spk:2.1, sur:on
----------------------
L  -------> fL
R  -------> fR
fL -------> fL
fR -------> fR
     ___
sL -|   |-> fL
sR -|   |-> fR
sC -|enc|-> sL
    |   |-> sR
    |___|-> sC


spk:5.1, sur:off
----------------------
L  -------> fL
R  -------> fR
fL -------> fL
fR -------> fR
sL -------> sL
sR -------> sR
sC -------> sC

spk:5.1, sur:copy
----------------------
L  -------> fL
   `------> sL
   `------> C
R  -------> fR
   `------> sR
   `------> C
fL -------> fL
fR -------> fR
sL -------> sL
sR -------> sR
sC -------> sC

spk:5.1, sur:on
----------------------
     ___
L  -|   |-> fL
R  -|   |-> fR
    |dec|-> sL
    |   |-> sR
    |___|-> sC
fL -------> fL
fR -------> fR
sL -------> sL
sR -------> sR
sC -------> sC


spk:4.1 - same as 5.1 except Center as in 2.1

---------------------------------
phisical meaning of sur controls:
----------------------------------------------------------------------------------
          |         2.1           |          4.1          |          5.1          |
----------------------------------------------------------------------------------
VCenterA  | C to fL/fR amount     | C to fL/fR amount     | L/R to C amount       |
VRearA    | sR/sR to fL/fR amount | L/R to sL/sR amount   | L/R to sL/sR amount   |
VRearW    | width of encoded rear | width of decoded rear | width of decoded rear |
VRearD    |         n/a           | delay of decoded rear | delay of decoded rear |

So.. ok, in other words:
Sur:Off  - means "What you hear is what you play"
    (e.g. "normal" mode - nothing happens with the sound except mixing L/R into fL/fR)
Sur:Copy - "You hear everything you play with all of your speakers"
    (e.g. "dummy heads" mode)
Sur:On - same as Copy with ~phase encoding/decoding applied
    (e.g. "dumb heads" mode)

Rswave2k2 · Sep 5, 2004, 12:40 PM

wow thanks for the help and the sticky.

Russ · Nov 28, 2007, 03:57 PM

Here is an updated version of Max's routing diagram. It is almost the same, except that it uses the current input/output names, and the 2.1 modes appear to be a little different. The diagram is based on the code used in Surrounder+.

Note that the diagram does not show the Bass Redirection stuff.

Code:

spk:2.1, sur:off
----------------------------
inL    -----|-> fL
in_nw  -----|

inR    -----|-> fR
in_ne  -----|

spk:2.1, sur:copy
----------------------------
inL    -----|-> fL
in_nw  -----|
in_sw  -----|
in_n   -----|

inR    -----|-> fR
in_ne  -----|
in_se  -----|
in_n   -----|


spk:2.1, sur:on
----------------------------
         ___
inL    -|   |
in_nw  -|   |-> fL 
in_ne  -|   |
in_n   -|enc|
in_sw  -|   |
in_se  -|   |-> fR 
inR    -|___|

spk:5.1, sur:off
----------------------------
inL    -----|-> fL
in_nw  -----|

inR    -----|-> fR
in_ne  -----|

in_sw  -------> sL
in_se  -------> sR
in_n   -------> Center

spk:5.1, sur:copy
----------------------------
inL    -----|-> fL
in_nw  -----|

inR    -----|-> fR
in_ne  -----|

inL    -----|-> sL
in_sw  -----|

inR    -----|-> sR
in_se  -----|

inL    -----|-> Center
inR    -----|
in_n   -----|

spk:5.1, sur:on
----------------------------
         ___
        |   |-> fL 
inL    -|   |-> fR
        |dec|-> sL
inR    -|   |-> sR
        |___|-> Center        
in_nw  -------> fL
in_ne  -------> fR
in_sw  -------> sL
in_se  -------> sR
in_n   -------> Center

LFE input/output works as follows (not including Bass Redirection stuff):

The LFE output is only used when "Use Subwoofer output" is enabled. In this case, LFE Out = LFE In, with no mixing of LFE into other channels.

If "Use Subwoofer output" is disabled:
If Surround is OFF, LFE input is not used, otherwise:
In 2.1 Speaker mode, LFE input (half) is subtracted from the resulting downmix.
In all other speaker modes, LFE input (half) is subtract from inL/inR, and the result is used for upmixing/downmixing.

Russ · Dec 2, 2007, 12:35 PM

Input/output names
-------------------

L/R are the generic left/right inputs.
Input here is upmixed according to Surrounder's settings.

N/S/W/E/NW/NE/SW/SE = Directional indicators like those found on a
compass (except 'N' is always directly in front of you).

fL/fR = Front Left/Right
sL/sR = Surround/Rear Left/Right
Center = Center (front)
LFE = LFE

6.1 Mode:
sCenter1 = Rear Center

7.1 Mode:
sCenter1 = Side Left
sCenter2 = Side Right

Code:

fL · · · · · ·  C  · · · · · · fR
·                               ·
·               N               ·
·      NW       ·       NE      ·
·         ·     ·     ·         ·
·           ·   ·   ·           ·
·             · · ·             ·
·     W · · · · + · · · · E     ·
·             · · ·             ·
·           ·   ·   ·           ·
·         ·     ·     ·         ·
·      SW       ·       SE      ·
·               S               ·
·                               ·
sL · · · · · · · · · · · · · · sR

brainless_beginner · Jan 21, 2008, 03:57 PM

Is it possible somehow to have really stereo surround? i mean left surr and right surr separately

Russ · Jan 21, 2008, 05:39 PM

I am not sure what you mean, sL and sR and separate. The only mixing between the two (IIRC) is from the rear width setting (VRearW). If you do not want any mixing, then set VRearW to 0.

brainless_beginner · Jan 22, 2008, 04:12 PM

i mean when VRearW=1 the sounds from sl and sr speakers are the same (kinda mono from both)

brainless_beginner · Jan 22, 2008, 04:18 PM

i guess it's achived by substracting L from R or vice versa resulting in

L-R=SL-SR or
R-L=SL-SR

i mean to have only SL from SL spk and SR from SR spk

Russ · Jan 22, 2008, 07:38 PM

Right, that is how width works.

i.e. (something like this)
sL = VRearD_Delayed ( (inL * VRearA) - (inR * (VRearW * VRearA)) )
sR = VRearD_Delayed ( (inR * VRearA) - (inL * (VRearW * VRearA)) )

So again, set VRearW to 0, if you do not want that behavior.

BTW: Those settings only effect upmixing/downmixing.