gs9023-cfy ETC-unknow, gs9023-cfy Datasheet - Page 14

• Manufacturer Part Number: gs9023-cfy
• Description: Embedded Audio Codec
• Manufacturer: ETC-unknow

video standards are listed in Table 6. In a component video
signal, a maximum of 4 audio control packets can be
multiplexed in a cascade connection. On power up, audio
group 1 is selected by default.
The GS9023 determines if multiplexing is possible by
searching for the first free location in the HANC space after
the signal EAV and calculates if there is sufficient remaining
space to insert the audio packet. Existing ancillary data
packets (inserted by previous devices) in the video signal
must be contiguous from the beginning of the HANC space
or the insertion of a new audio data packet may overwrite
existing data. In cases where an audio control data packet
does not fit inside the remaining HANC space, the audio
control packet is discarded. In this case, the “ACERR” bit of
Host Interface Register #7h is HIGH indicating an audio
control packet multiplexing error. The error bit is cleared
when accessed by the Host Interface.
The audio control packet structure as described in SMPTE
272M is shown in Figure 8.
The audio control packets words are defined as follows:
ADF: Ancillary Data Flag. The ancillary data flag marks the
beginning of an ancillary packet and is automatically
generated by the GS9023.
DID: Data ID. Audio control packets corresponding to an
audio group are selected by programming “ACID[3:0]” of
Host Interface Register #4h for audio groups 1 to 4 as
follows:
Group 1: Fh (1EFh)
Group 2: Eh (2EEh)
Group 3: Dh (2EDh)
Group 4: Ch (1ECh)
NOTE: The six most significant bits of the DID are
automatically generated by the GS9023.
DBN: Data Block Number. The data block number is used
when data blocks within a common data ID are to be linked
or to distinguish consecutive data blocks within a common
data ID. The data block number continuously increments
from 1 to 255 and is generated automatically by the
GS9023.
GENNUM CORPORATION
* The ancillary data flag, ADF, is one word in composite systems (ANSI/SMPTE 259M) and three words
in component systems (ANSI/SMPTE 125M).
Fig. 8: Audio Control Packet Structure
14
TABLE 6: Multiplexing Positions for Audio Control Packets
DC: Data Count. The data count represents the number of
data words to follow. The data count has a fixed value of
212h and is automatically generated by the GS9023.
AF1-2: Audio frame number for channels 1 and 2.
AF3-4: Audio frame number for channels 3 and 4.
For an audio sampling frequency of 48kHz, the audio frame
numbers are sequenced from one to five for 525 line video
standards and fixed at one for 625 line video standards.
The audio frame numbers, AF1-2 and AF3-4, are
automatically generated by the GS9023 and set to the
same value. The sequence count is started at one at the
first frame after ‘lock’ is achieved.
RATE: Sampling frequency. The GS9023 operates at a fixed
sampling frequency of 48kHz. The audio control packet
RATE word structure is shown in Table 7.
TABLE 7: Audio Control Packet Rate Word Structure
STANDARD
525/4:4:4:4
625/4:4:4:4
625/4:2:2P
525/16:9
625/16:9
525/D2
525/D1
625/D2
625/D1
VIDEO
BIT
b9
b8
b7
MULTIPLEXING
12/275
12/275
12/275
12/275
15/641
LINES
8/321
8/321
8/321
8/321
not used (fixed to 0)
y2 (MSB, fixed to 0)
RATE WORD
HORIZONTAL
not b8
STARTING
POSITION
1444
1924
2884
1444
2277
2884
1444
795
972
HORIZONTAL
POSITION
ENDING
522 - 45 - 05
1711
2283
3427
1035
1723
2299
3451
1723
849