GS9023 데이터 시트보기 (PDF) - Gennum -> Semtech
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GS9023 Datasheet PDF : 33 Pages
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Video signal before GS9023
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Video signal after GS9023 Insertion of Audio Group 1 ("CASCADE" = HIGH)
Fig. 4
In cases where an audio data packet does not fit inside the
remaining HANC space, the audio packet is discarded. In
this case, the “ADERR” bit of Host Interface Register #7h is
HIGH indicating an audio packet multiplexing error. The
error bit is cleared once accessed by the Host Interface.
By cascading four GS9023 devices, it is possible to
multiplex up to 16 audio channels (according to SMPTE
272) in a component video signal as shown in Figure 18.
NOTE: In the 525/D1 video format, only 15 channels of 24
bit audio can be multiplexed.
Cascade operation is not recommended with a composite
video signal, as there is insufficient HANC space for more
than four channels of audio. Audio packet insertion is not
guaranteed in this case.
The audio data packet structure as described in SMPTE
272M is shown in Figure 5.
The audio data 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 data packets corresponding to an
audio group are selected by programming “A20ID[3:0]” of
Host Interface Register #3h for audio groups 1 to 4 as
follows:
Group 1: Fh (2FFh)
Group 2: Dh (1FDh)
Group 3: Bh (1FBh)
Group 4: 9h (2F9h)
NOTE: The six most significant bits of the DID are internally
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.
DC: Data Count. The data count represents the number of
user data words to follow (maximum of 255 words). The
data count is automatically generated by the GS9023.
CS: Checksum. The checksum consists of nine bits. The
checksum is used to determine the validity of the words
data ID through user data. It is the sum of the nine least
significant bits of the words data ID through user data. The
checksum is automatically generated by the GS9023.
The serial audio data samples, are mapped into three
contiguous ancillary data words (X, X+1, X+2) as shown in
Table 3.
X X+1 X+2 X X+1 X+2 X X+1 X+2
X X+1 X+2 X X+1 X+2 X X+1 X+2
* The ancillary data flag, ADF, is one word in composite systems (ANSI/SMPTE 259M) and three words
in component systems (ANSI/SMPTE 125M).
Fig. 5: Audio Data Packet Structure with 4 Audio Channels, 1 Audio Group
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