STA013B View Datasheet(PDF) - STMicroelectronics

Part Name

Description

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STA013B

MPEG 2.5 LAYER III AUDIO DECODER

STMicroelectronics 

STA013 - STA013B - STA013T

TONE_ATTEN

Address: 0x7D

Type: RW

Software Reset: 0x00

Hardware Reset: 0x00

MSB

LSB

b7 b6 b5 b4 b3 b2 b1 b0

TA7 TA6 TA5 TA4 TA3 TA2 TA1 TA0

In the digital output audio, the full signal is

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.

MSB

LSB

b7 b6 b5 b4 b3 b2 b1 b0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

1

0

0

0

0

1

0

1

0

0

0

0

0

0

0

1

1

.

.

.

0

0

0

0

1

0

1

0

0

0

0

0

1

0

1

1

0

0

0

0

1

1

0

0

5. GENERAL INFORMATION

5.1. MPEG 2.5 Layer III Algorithm.

ATTENUATION

-1.5dB step

0dB

-1.5dB

-3dB

-4.5dB

-15dB

-16.5dB

-18dB

DEMULTIPLEXING

&

ERROR CHECK

HUFFMAN

DECODING

INVERSE

QUANTISATION

&

DESCALING

IMDCT

INVERSE

FILTERBANK

ANCILLARY DATA

ENCODED AUDIO

BITSTREAM (8Kbit/s ... 128Kbit/s)

SIDE INFORMATION

DECODING

D98AU903

STEREOPHONIC AUDIO

SIGNAL (2*768Kbit/s)

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-

pling frequencies. The time duration of the Layer

III frames is shown in Tab 2.

Table2: MPEG Layer III Frames Time Duration

Sampling Frequency (KHz) 48

44.1

32

MPEG Frame Lenght (ms) 24

29

36

24

22.5

16

24

29

36

12 11.025 8

48

48

72

27/38

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