GS2970 Datasheet, PDF (64/145 Pages) Semtech Corporation – 3Gb/s, HD, SD SDI Receiver Complete with SMPTE Audio and Video Processing

4.16.3 EDH CRC Error Detection
The GS2970 also calculates Full Field (FF) and Active Picture (AP) CRC's according to
SMPTE RP165 in support of Error Detection and Handling packets in SD signals.
These calculated CRC values are compared with the received CRC values.
Error flags for AP and FF CRC errors are provided and each error flag is a logical OR of
field 1 and field 2 error conditions.
The AP_CRC_ERR bit in the VIDEO_ERROR_STAT_X register is set HIGH when an Active
Picture CRC mismatch has been detected in field 1 or 2.
The FF_CRC_ERR bit in the VIDEO_ERROR_STAT_X register is set HIGH when a Full
Field CRC mismatch has been detected in field 1 or 2.
EDH CRC errors are only indicated when the device is operating in SD mode and when
the device has correctly received EDH packets.
4.16.4 HD & 3G Line Number Error Detection
If a mismatch in the calculated and received line numbers is detected, the LNUM_ERR
bit in the VIDEO_ERROR_STAT_X register is set HIGH.
4.17 Ancillary Data Detection & Indication
The GS2970 detects ancillary data in both the vertical and horizontal ancillary data
spaces. Status signal outputs Y/1ANC and C/2ANC are provided to indicate the position
of ancillary data in the output data streams. These signals may be selected for output on
the multi-function I/O port pins (STAT[5:0]).
The GS2970 indicates the presence of all types of ancillary data by detecting the 000h,
3FFh, 3FFh (00h, FFh, FFh for 8-bit video) ancillary data preamble.
NOTE: Both 8 and 10-bit ancillary data preambles are detected by the device.
By default (at power up or after system reset) the GS2970 indicates all types of ancillary
data. Up to 5 types of ancillary data can be specifically programmed for recognition.
For HD video signals, ancillary data may be placed in both the Y and Cb/Cr video data
streams separately. For SD video signals, the ancillary data is multiplexed and combined
into the YCbCr data space.
For 3G signals, ancillary data may be placed in either or both of the virtual interface data
streams. Both data streams are examined for ancillary data.
For a 3G data stream formatted as per Level A mapping:
• The ancillary data is placed in Data Stream 1 first, with overflow into Data Stream 2
• SMPTE 352M packets are duplicated in both data streams
For a 3G data stream formatted as per Level B mapping:
• Each multiplexed data stream forming the 3G signal contains ancillary data
embedded according to SMPTE 291M
• Each multiplexed data stream forming the 3G signal contains SMPTE 352M packets
embedded according to SMPTE 425M
GS2970 3Gb/s, HD, SD SDI Receiver Complete with
SMPTE Audio and Video Processing
Data Sheet
47478 - 4
September 2012
64 of 145