sta003t STMicroelectronics, sta003t Datasheet - Page 26

• Manufacturer Part Number: sta003t
• Description: Mpeg 2.5 Layer Iii Audio Decoder
• Manufacturer: STMicroelectronics

STA003T
TONE_ATTEN
Address: 0x7D
Type: RW
Software Reset: 0x00
Hardware Reset: 0x00
5. GENERAL INFORMATION
5.1. MPEG 2.5 Layer III Algorithm.
5.2 - MPEG Ancillary Data Description:
As specifyed in the ISO standard, the MPEG
Layer III frames have a variable bit lenght, and
are constant in time depending on the audio sam-
Table2: MPEG Layer III Frames Time Duration
26/32
MSB
TA7
MSB
Sampling Frequency (KHz)
MPEG Frame Lenght (ms)
b7
b7
BITSTREAM (8Kbit/s ... 128Kbit/s)
0
0
0
0
0
0
0
ENCODED AUDIO
TA6
b6
b6
0
0
0
0
0
0
0
TA5
b5
b5
0
0
0
0
0
0
0
DEMULTIPLEXING
ANCILLARY DATA
ERROR CHECK
TA4
b4
b4
&
0
0
0
0
0
0
0
TA3
b3
b3
0
0
1
0
1
1
1
48
24
TA2
b2
DECODING
b2
HUFFMAN
0
0
1
0
0
0
0
TA1
b1
b1
LSB
TA0
32
36
0
0
1
1
1
1
0
b0
SIDE INFORMATION
DECODING
LSB
QUANTISATION
b0
.
.
.
0
1
0
0
1
0
1
DESCALING
INVERSE
In the digital output
achieved with 0 dB of attenuation. For this rea-
son, before applying Bass & Treble Control, the
user has to set the TONE_ATTEN register to the
maximum value of enhancement is going to per-
form.
For example, in case of a 0 dB signal (max. level)
only attenuation would be possible. If enhance-
ment is desired, the signal has to be attenuated
accordingly before in order to reserve a margin in dB.
An increment of a decimal unit corresponds to a Tone
Attenuation step of 1.5dB.
pling frequencies. The time duration of the Layer
III frames is shown in Tab 2.
&
24
24
IMDCT
16
36
ATTENUATION
D98AU903
-1.5dB step
-16.5dB
-1.5dB
-4.5dB
-15dB
-18dB
-3dB
0dB
audio, the full signal is
FILTERBANK
INVERSE
12
48
STEREOPHONIC AUDIO
SIGNAL (2*768Kbit/s)
72
8