Device overview STA382BWS
The mentioned hyperlink in this section relates to the default New Map
Section 6: Register description: New Map
.
4.1 Processing data path
The whole STA382BWS processing chain is composed of two consecutive sections. In the first one dual-channel processing is implemented (
Figure 4
) and then each channel is fed into the post-mixing block allowing to generate either a third channel (typically used in 2.1 output configurations together with crossover filters) or to have the channels processed by the dual-band DRC block (2.0 output configuration with crossover filters used to define the cutoff frequency of the two bands).
The first section begins with a 2x oversampling FIR filter allowing 2*Fs audio processing.
Then a selectable high-pass filter removes the DC level (enabled if HFB = 0). The channel 1 and 2 processing chain can include up to 8 filters, depending on the selected configuration
(bits BQL, BQ5, BQ6, BQ7 and XO[3:0]). By default, 4 independent filters per channel are enabled, plus the pre-configured Bass and Treble controls (BQL=0, BQ5=0, BQ6=0,
BQ7=0).
The STA382BWS offers the possibility to share the filter coefficients between the two processing channels. When this option is set (BQL=1), filters from the 1st to the 4th have the same coeffcients set. Under these conditions, filters from the 5th to 7th can be used as custom filters as well (provided the relevant BQx bits are set). Once again filter coefficients are shared between the two processing channels.
Moreover the common 8th filter, from the subsequent processing section, can be available on both channels (provided the pre-defined crossover frequencies are not used, XO[3:0]=0, and the dual-band DRC is not used).
Figure 4.
Processing path, first part
Sa mpling Fre qu ency = 2xF s
X2Over-
sa mpling
FIR
-
Pres c a le
Hi-P ass
Filter
Bi qua d
#1
Bi qua d
#2
Bi qua d
# 3
Bi qua d
#4
De-emph
Or
Bi qua d #5
B ass
Or
Bi qua d #6
Tre b le
Or
Bi qua d #7
U s erd Defined Filter s Tone Control
Sa mpling Fre qu ency = F s
I2 S Inp u t
Interf a ce
Obsolete Product(s) - Obsolete Product(s)
X2OverDe-emph B ass Tre b le
PreHi-P ass Bi qua d Bi qua d Bi qua d Bi qua d R
sa mpling
FIR
s c a le Filter #1 #2 # 3 #4
Or
Bi qua d #5
Or
Bi qua d #6
Or
Bi qua d #7
Sa mpling Fre qu ency = 2xF s
U s erd Defined Filter s Tone Control
L
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STA382BWS Device overview
The second processing stage embeds a mixing block, a biquadratic/crossover filter, a DRC stage, the volume control, a DC cut filter and a post scaler. Depending on the device settings, the following configuration and features are available:
●
2.1 output with individually configurable anticlipper/DRCs ( Figure 5 ): two individually
configurable DRC/anticlippers are available while the eighth biquadratic filter, jointly with the mixer block, can be used to perform LFE. This configuration and features ensure the backward compatibility with previous Sound Terminal
®
products.
Figure 5.
Processing path, second part: 2.1 output with individually configurable anticlipper/DRCs
L
R
C1Mx1
+
C1Mx2
Ch a n n el ½
Bi q ua d # 8
--------------
Hi-p ass XO
Filter
Ch a n n el 1
Vo l u me
An ti-clipper
/
DRC
DC C u t
Filter
Po s t S c a le
C2Mx1
+
C2Mx2
Ch a n n el ½
Bi q ua d # 8
--------------
Hi-p ass XO
Filter
Ch a n n el 2
Vo l u me
An ti-clipper
/
DRC
DC C u t
Filter
Po s t S c a le
C 3 Mx1
+
C 3 Mx2
Ch a n n el 3
Bi q ua d # 8
--------------
Lo w-p ass XO filter
U s er-D efined
M ix C oeffic ient s
C ro s s ov er F re qu enc y
D eterm ined b y XO S etting
(U s er Defin ed If
XO =0000)
Ch a n n el 3
Vo l u me
An ti-clipper
/
DRC
DC C u t
Filter
Po s t S c a le
Obsolete Product(s) - Obsolete Product(s)
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Device overview STA382BWS
● 2.0 output with B
2
DRC (
Figure 6 ): the mixer and the eighth biquadratic filter are used to
divide the channel into two sub-bands, then each sub-band is independently processed by a DRC block. The two bands are then re-composed and fed to the following processing blocks. The crossover frequency is user-selectable. This configuration and features ensure the backward compatibility with the previous Sound Terminal
® products. For further information please refer to
Chapter 6.11.1: Dual-band DRC .
Figure 6.
Processing path, second part: 2.0 output with B
2
DRC
Ch a nnel 3
Vol u me
DRC 2
L
R
C1Mx1
+
C1Mx2
C2Mx1
+
C2Mx2
B 2 DRC
Hi-p ass XO filter
-
+
B 2 DRC
Hi-p ass XO filter
- +
Ch a nnel 1
Vol u me
Ch a nnel 2
Vol u me
DRC 1
+
DC C u t
Filter
DRC 1
Po s t S c a le
C 3 Mx1
+
C 3 Mx2
Ch a nnel 3
Vol u me
DRC 2
+
DC C u t
Filter
Po s t S c a le
●
U s er-Defined
Mix Coefficient s
Cro ss over Fre qu ency
Determined b y XO S etting
(U s er Defined If
XO=0000)
2.1 output with STCompressor
TM
(
Figure 7 ): the STA382BWS embeds the latest, state-
of-the-art multi-band dynamic, range compressor, called STCompressor
TM
. When using this configuration, up to 10 biquad filters are available for dedicated processing.
Please refer to Section 4.3: STCompressorTM
for further information about this feature.
Figure 7.
Processing path, second part: 2.1 output configuration with
STCompressor
TM
L
R
C1Mx1
+
C1Mx2
Ch a nnel ½
Bi qua d # 8
--------------
Hi-p ass XO
Filter
S TCompre ss or
Vol u me
And
Limiter
DC C u t
Filter
Po s t S c a le
C2Mx1
Ch a nnel ½
Bi qua d # 8 Vol u me
+ S TCompre ss or And
Limiter
DC C u t
Filter
Po s t S c a le --------------
Hi-p ass XO
C2Mx2
Filter Obsolete Product(s) - Obsolete Product(s)
C 3 Mx1
Ch a nnel 3
+
Bi qua d # 8
--------------
Low-p ass XO filter
Vol u me
And
Limiter
DC C u t
Filter
Po s t S c a le
C 3 Mx2
U s er-Defined
Mix Coefficient s
Cro ss over Fre qu ency
Determined b y XO S etting
(U s er Defined If
XO=0000)
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