GS2971A Datasheet, PDF (71/152 Pages) Gennum Corporation – Integrated audio clock generator

If both DID and SDID values are non-zero, then the received ancillary data type must
match both the DID and SDID before Y/1ANC and/or C/2ANC is set HIGH.
NOTE 1: For 3G Level B data, the ANC_TYPE_DS1 registers are valid for Data Stream 1,
and a second set of five ANC_TYPE registers (ANC_TYPE_DS2) is provided for detection
of specific ancillary data in Data Stream 2.
NOTE 2: SMPTE 352M Payload Identifier packets and Error Detection and Handling
(EDH) Packets are always detected by the GS2971A, irrespective of the settings of the
ANC_TYPE registers.
4.17.2 SMPTE 352M Payload Identifier
The GS2971A automatically extracts the SMPTE 352M payload identifier present in the
input data stream for SD, HD, and 3G Level A signals. The four word payload identifier
packets are written to VIDEO_FORMAT_X_DS1 and VIDEO_FORMAT_X_DS2 bits
accessible through the host interface.
The device also indicates the version of the payload packet in the VERSION_352M bit of
the DATA_FORMAT_DSX register. When the SMPTE 352M packet is formatted as a
“version 1” packet, the VERSION_352M bit is set HIGH, when the packet is formatted as
a “version 2” packet, this bit is set LOW.
The VIDEO_FORMAT_352_A_X and VIDEO_FORMAT_352_B_X registers are only
updated if there are no checksum errors in the received SMPTE 352M packets.
By default (at power up or after system reset), the VIDEO_FORMAT_X_DS1 and
VIDEO_FORMAT_X_DS2 bits are set to 0, indicating an undefined format.
NOTE 1: When 3G Level B data is detected by the device, the user needs to extract the
SMPTE 352M Payload Identifier packets by using the ANC packet extraction block - they
are not detected and extracted automatically. In this case:
• The VD_STD_ERR bit is not valid
• 352M extraction is only done on one data stream or the other, not both
simultaneously (Link A or Link B selected via the host interface)
• Previously embedded 352M packets can be deleted on one data stream only (using
the ANC_DATA_DELETE bit, see Section 4.18.8), but these packets are replaced with
10-bit Y/C blanking values only
• It is necessary to manually extract the SMPTE 352M data by programming the DID,
SDID and line number information into the ANC data extraction block
NOTE 2: SMPTE 352M packet regeneration is enabled by default for 3G Level B inputs,
and should be disabled through the host interface if Level B to Level A conversion is not
enabled.
4.17.2.1 SMPTE 352M Payload Identifier Usage
The SMPTE 352M Payload Identifier is used to confirm the video format identified by the
Automatic Video Standards Detection block (see Section 4.17.4)
GS2971A 3Gb/s, HD, SD SDI Receiver
Data Sheet
54311 - 2
September 2012
71 of 152