MAS3587F Micronas, MAS3587F Datasheet - Page 41

• Manufacturer Part Number: MAS3587F
• Description: MPEG Layer 3 Audio Encoder/Decoder
• Manufacturer: Micronas

ADVANCE INFORMATION
3.3.5. DSP Volume Control
The digital baseband volume matrix is used for control-
ling the digital gain of the decoder as shown in Fig. 3–
3. This volume control is effective on both, the digital
audio output and the data stream to the D/A convert-
ers. The values are in 20-bit 2’s complement notation.
Table 3–9 shows the proposed settings for the 4 vol-
ume matrix coefficients for stereo, left and right mono.
The gain factors are given in fixed point notation
( 1.0 2
The DSP volume control is available in Decoder Mode
only.
Fig. 3–3: Digital volume matrix
Table 3–10: Content of D0:fd5 after reception of 19 ancillary bits.
Table 3–11: Content of D0:fd6 after reception of 19 ancillary bits.
Micronas
right audio
left audio
D0:fd5
Ancillary
Data
D0:fd6
Ancillary
Data
19
= 80000
MSB
4th
bit
MSB
x
1
1
1
1
hex
14
5th
bit
14
x
).
13
6th
bit
13
x
RR
LR
RL
LL
12
...
12
x
11
...
11
x
+
+
10
...
10
x
9
...
9
x
8
...
8
x
Table 3–9: Settings for the digital volume matrix
If channels are mixed, care must be taken to prevent
clipping at high amplitudes. Therefore the sum of the
absolute values of coefficients for one output channel
should be less than 1.0.
For normal operating conditions it is recommended to
use the main volume control of the audio codec
instead (register 00 10
Memory
Name
Stereo
(default)
Mono left
Mono right
7
...
7
x
6
...
6
x
D0:354
LL
0
1.0
1.0
5
...
5
x
hex
4
...
4
x
D0:355
LR
0
0
of the audio codec).
1.0
3
...
3
x
MAS 3587F
D0:356
RL
0
0
1.0
2
17th
bit
2
first
bit
1
18th
bit
1
2nd
bit
D0:357
RR
0
1.0
1.0
LSB
last
bit
LSB
3rd
bit
41