GS9023 datasheet(12/33 Pages) ETC

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The audio packet data sample bits are defined as follows:

Z: The Z flag is set HIGH at the same sample coincident

with the beginning of a new AES channel status block

(frame 0) and is otherwise set LOW. In non-AES/EBU data

input formats this bit is set to the value of the SAFA/B input

pins at the rising edge of WCINA/B.

ch[1:0]: Identification of the channels in an audio group as

shown in Table 4.

aud[19:0]: Twos complement linearly represented audio

data. The audio data is input from the AINA and AINB pins.

V: AES/EBU sample validity bit. If the audio sample is valid

the bit is set LOW. If the audio sample is invalid, the bit is

set HIGH. In non-AES/EBU data input formats, this bit is set

to the value of the VFLA/B input pins at the rising edge of

WCINA/B.

U: AES/EBU user bit. In non-AES/EBU data input formats,

this bit is set to the value of the UDA/B input pins at the

rising edge of WCINA/B.

C: AES/EBU audio channel status bit. In non-AES/EBU data

input formats this bit is set to the value of the CSA/B input

pins at the rising edge of WCINA/B.

P: Even parity for the 26 previous bits in the audio data

sample (excludes b9 in the first and second words).

NOTE: The P bit is not the same as the AES/EBU parity bit.

This bit is automatically generated by the GS9023.

Extended Audio Data Packets

The GS9023 can multiplex 20 or 24 bit audio samples. For

24 bit audio samples, the 20 MSBs of a 24 bit audio sample

are contained in the audio data packets and the 4 LSBs are

contained in an extended audio data packet as defined in

SMPTE 272. The extended audio data packet is multiplexed

immediately following the corresponding audio data packet.

See Figure 6.

Fig. 6

TABLE 3: Audio Packet Data Sample Structure

BIT

WORD X

WORD X+1

WORD X+2

not b8

aud 5

aud 14

aud 4

aud 13

aud 3

aud 12

aud 2

aud 11

aud 1

aud 10

aud 19 (MSB)

aud 0 (LSB)

aud 9

aud 18

ch 1 (MSB)

aud 8

aud 17

ch 0 (LSB)

aud 7

aud 16

aud 6

aud 15

TABLE 4: Channel Identification Within The Audio Groups

GROUP

Channel

Empty

Video signal before GS9023

Empty

Video signal after GS9023 Insertion of Audio Group 2 & Extended

Audio Group 2 ("CASCADE" = HIGH)

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