GS1582 Datasheet, PDF (41/115 Pages) Gennum Corporation – Multi-Rate Serializer with Cable Driver, Audio Multiplexer and ClockCleaner™

Since the audio core multiplexes audio packets on to lines where the ancillary data
packet containing EDH checkwords and status flags is to be placed (lines 9 and 272 in
525, and lines 5 and 318 in 625), if there is insufficient horizontal ancillary data space
available after audio multiplexing, the EDH block will overwrite audio packets. This
problem may occur in both 525 and 625 when 16 channels (4 audio groups) of 24-bit
audio are embedded.
NOTE 1: The audio sample distribution used by the SD audio core for both 525 and 625
will increase the available space in the horizontal ancillary data space.
NOTE 2: Due to the large size of the horizontal ancillary data space in 720p/24, 720p/25
and 720p/30 video standards, the maximum number of ancillary data words the audio
core can process is limited to 1024 when configured to these standards.
Table 4-4 lists the data ID's and packet lengths for arbitrary, EDH, SDTI header and
SMPTE 352M packets.
When the presence of a SMPTE 352M packet is detected, the audio core extracts and
stores the packet for re-insertion. Audio data packets will always be placed after the
SMPTE 352M packet.
Table 4-4: Non-audio Ancillary Data Packet DIDs
Ancillary Data Packet
Arbitrary (SMPTE 291M)
EDH (RP 165)
Payload Identifier (SMPTE 352M)
SDTI Header (SMPTE 305M)
DID
User
1F4h
241h
140h
SDID
User
–
101h
101h
Packet Length (Words)
262 max
23
11
53
NOTE: When serializing SDTI signals, it is recommended that the user ensure there are
no SMPTE 352M packets present in the input video data.
4.7.6 Audio Packet Multiplexing
The SD core places audio data packets contiguously after the EAV. Any Extended Audio
Data Packets are placed immediately following the Audio Data Packet of the same audio
group.
The HD core places audio data packets contiguously after the two line CRC words.
In cases where the SMPTE 352M packet or SDTI header are present after the EAV or CRC,
the audio data will be placed contiguously from the 352M or SDTI header packets. On
lines where the 352M or SDTI header packets are present, there may be insufficient
HANC space for embedding 4 audio groups. If there is insufficient HANC space
available, the 352M or SDTI header packets are always re-inserted and the remaining
audio group packet to be inserted is discarded.
GS1582 Multi-Rate Serializer with Cable Driver, Audio
Multiplexer and ClockCleaner^TM
Data Sheet
40117 - 4
December 2011
41 of 115