ML7204-003 datasheet(39/214 Pages) LAPIS

39 / 214 page

FEDL7204-003-02

ML7204-003

39/214

A. Speech CODEC coding format switching control on the transmit side

A-1. G.729.A

 G.711 (-law and A-law) switching control (10 ms frame mode)

Figure 22 Speech CODEC Format Switching Control Method on the Transmit

Side G.729.A

G.711 <10 ms frame mode>

 G.729.A operation (before switching)

Operates according to the contents described in  Operation and  Error processing in Figure 14 G.729.A

transmit buffer control method at single-channel operation (10 ms/frame mode).

 Switching processing

Switch the Speech CODEC coding format from G729.A to G.711 within the valid MCU read period according

to the setting in the Speech CODEC selection register on the transmit side (TX_SCSEL[1:0]). When the

switching of the Speech CODEC coding format is detected, the LSI internal section discards the data currently

being encoded (T6 encoding data in the example shown above) and starts encoding in the G.711 coding format

from the next frame.

A read request is issued normally by FR0B also for the frame where coding format has been switched;

however, a transmit error (TXERR_CH1 = “1”) does not occur even if data read processing does not terminate

within the valid read period. If a transmit error occurred before this frame, this transmit error is cleared to

“0” at termination of this frame.

(Note)

If the coding format is switched outside of the valid MCU read period, the G.729.A

 G.711 switching

processing may be delayed by one frame. Therefore, check whether the transmit request is for the data

encoded in the G.729.A or encoded in the G.711 by referencing the transmit Speech CODEC operation mode

notification flag (TX_SCFLAG) when requesting transmission due to the fall of FR0B.

 G.711 operation (after switching)

Operates according to the contents that are described in  Operation and  Error processing in Figure 16

G.711 (

-law and A-law) transmit buffer control method (10 ms/frame mode) at single-channel operation.

FR0B

(Pin output)

MCU read

Valid read section

RE_SC5

RE_SC4

RE_SC3

Speech

CODEC

ENC

10 ms

T5(G.729.A)

T6(G.729.A)

T4(G.729.A)

G.729.A operation (before switching)

Switching processing

G.711 operation (after switching)

FR0_CH1

INTB

(Pin output)

FR0B

(Pin output)

MCU read

Valid read section

Speech

CODEC

ENC

10 ms

T7(G.711)

T8(G.711)

T9(G.711)

RE_SC7

T10(G.711)

RE_SC8

RE_SC9

FR0_CH1

INTB

(Pin output)

G.729.A

G.711

Transmit SC coding

format setting

TX_SCSEL[1:0]

G.729.A

G.711

Transmit SC operation

mode notification

TX_SCFLAG

ML7204-003 Datasheet(PDF) 39 Page - LAPIS Semiconductor Co., Ltd.

ML7204-003 Datasheet(HTML) 39 Page - LAPIS Semiconductor Co., Ltd.

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL