STA310 datasheet(69/90 Pages) STMICROELECTRONICS

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STA310

Description:

MP_DOWNMIX

MPEG downmix

Address: 0x6F

Type: R/W

Software Reset: 0x08

Hardware Reset: UND

Description:

In the table below, LO, RO, CO, LsO, RsO represent

the output channels after downmix, and L, R, C, LS,

RS are the audio channels.

The coefficients Kj, KC, Kr, KS, depend on the number

of input channels. In the above table, the equations

are given for a 5 channels input bitstream. If the input

bitstream does not contain five channels (L, C, R, LS,

RS), the coefficient “Kj” corresponding to the channel

not present is equal to 0.

If the MPEG bitstream contains only one surround

channel (S), replace (KS x (LS + RS)), (KS x LS and

(KS x RS) by (KS x S) in the above equations.

Bitfield

Description

When MC=1, the multi-channel part of the

bitstream is not decoded, only the MPEG-1

compatible bitstream is decoded. Bit MC must

be set to 1 for an MPEG-1 bitstream.

DEN

De-normalization: set DEN=0 for MPEG1

signals, and set DEN=1 for MPEG2 multi-

channel signals

When DEN=1, MPEG2 multi-channel signals

L, C, R, LS and RS can be de-normalized.

The signals must first be inverse-weighted

then multiplied by the de-normalization factor.

This undoes the attenuation carried out at the

encoder side to avoid overload when

calculating the compatible signals (see MPEG

13818-3 specifications).

7654321

Value

Output Mode

Comment

0x00

1/0 (C) = Mono

CO = Kj x L + C + Kr x R + KS

(LS + RS)

0x01

2/0 (L, R) =

Stereo

LO = (L + KC x C + KS x LS)/

(1 + KC + KS),

RO = (R + KC x C + KS x RS)/

(1 + KC + KS)

0x02 3/0 (L, C, R)

LO = L + KS x LS, RO = R +

KS x RS, CO = C

0x03 2/1 (L, R, S)

LO = L + KC x C, RO = R + KC

x C, LsO = RsO = KS x (LS +

RS)

0x04 3/1 (L, C, R, S)

LO = L, RO = R, CO = C, LsO

= RsO = KS x (LS + RS)

0x05 2/2 (L, R, LS, RS)LO = L + KC x C, RO = R + KC

x C, LsO = LS, RsO = RS

0x06 3/2 (L, C, R, LS,

RS)

LO = L, RO = R, CO = C, LsO

= LS, RsO = RS

0x09 2/0 (Dolby

surround LT, RT)

LT = (L + 0.707C - 0.707 x 0.5

(LS + RS)) /2.414,

RT = (R + 0.707C + 0.707 x

0.5 (LS + RS)) /2.414

0x0A 2/0 Karaoke

capable: V1 ON,

V2 ON

Lk = L + 0.707 A1 + 0.707 G,

Rk = R + 0.707 A2 + 0.707 G

0x0B 2/0 Karaoke

Capable: V1 ON,

V2 OFF

Lk = L + 0.707 A1 + 0.707 G,

Rk = R + 0.707 G

0x0C 2/0 Karaoke

Capable: V1 OFF,

V2 ON

Lk = L + 0.707 G, Rk = R +

0.707 A2 + 0.707 G

0x0D 2/0 Karaoke

Capable: V1 OFF,

V2 OFF

Lk = L + 0.707 G, Rk = R +

0.707 G

0x0E 2/0 Karaoke

Capable: V1 ON,

V2 OFF (Dolby

Digital like)

Lk = L + 0.707 A1 + 0.707 G,

Rk = R + 0.707 A1 + 0.707 G

0x0F 2/0 Karaoke

Capable: V1 OFF,

V2 ON (Dolby

Digital like)

Lk = L + 0.707 A2 + 0.707 G,

Rk = R + 0.707 A2 + 0.707 G

0x1A 3/0 Karaoke

Capable: V1 ON,

V2 ON

Lk = L + 0.707 A1, Ck = G, Rk

= R + 0.707 A2

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