GS9092ACNE3 datasheet(43/63 Pages) GENNUM

43 / 63 page

GS9092A GenLINX® III 270Mb/s Serializer for SDI and

DVB-ASI

Data Sheet

34715 - 4

May 2010

43 of 63

EDH error flags (EDH, EDA, IDH, IDA, and UES) for ancillary data, full field, and active

picture will also be inserted. These flags must be programmed into the EDH_FLAG

registers of the device by the application layer (Table 3-8).

NOTE 1: It is the responsibility of the user to ensure that the EDH flag registers are

updated once per field.

The prepared EDH packet will be inserted at the appropriate line of the video stream

according to RP 165. The start pixel position of the inserted packet will be based on the

SAV position of that line such that the last byte of the EDH packet (the checksum) will be

placed in the sample immediately preceding the start of the SAV TRS word.

NOTE 2: It is also the responsibility of the user to ensure that there is sufficient space in

the horizontal blanking interval for the EDH packet to be inserted.

CRC Update of Existing Packets

When the EDH_CRC_UPDATE bit is set HIGH, the GS9092A will not generate any new

EDH packets, but will instead update the CRC bytes of the existing EDH packets within

the input video data stream. Incoming EDH flags are preserved and can be read from the

EDH_FLAG register, which becomes read-only (Table 3-8).

When EDH packets are detected, the EDH_FLAG register is updated on each field. These

registers will be cleared LOW if no EDH packet is detected during blanking at the end of

the vertical blanking period (falling edge of V).

The validity or ‘V’ bits of the incoming EDH packet will also be set to ‘1’ to denote that the

CRC calculations are valid. The EDH packet checksum word is also re-calculated and

re-inserted.

When incoming EDH packets are updated, the location of the packets within the video

stream remains unchanged. EDH packets that are to be updated can be present

anywhere within the horizontal blanking region of the vertical blanking period.

GS9092ACNE3 Datasheet(PDF) 43 Page - Gennum Corporation