GS2970 Datasheet, PDF (69/145 Pages) Semtech Corporation – 3Gb/s, HD, SD SDI Receiver Complete with SMPTE Audio and Video Processing

When operating in SD mode, only the YCS_ERR bit is set HIGH when checksum errors
are detected.
4.17.3.1 Programmable Ancillary Data Checksum Calculation
As described above, the GS2970 calculates and compares checksum values for all
ancillary data types by default. It is possible to program which ancillary data types are
checked as described in Section 4.17.1.
When so programmed, the GS2970 only checks ancillary data checksums for the
specified data types, ignoring all other ancillary data.
The YCS_ERR and/or CCS_ERR bits in the VIDEO_ERROR_STAT_X register are only set
HIGH if an error condition is detected for the programmed ancillary data types.
4.17.4 Video Standard Error
If a mismatch between the received SMPTE 352M packets and the calculated video
standard occurs, the GS2970 indicates a video standard error by setting the
VD_STD_ERR bit of the VIDEO_ERROR_STAT_X register HIGH.
The device detects the SMPTE 352M Packet version as defined in the SMPTE 352M
standard. If the incoming packet is Version Zero, then no comparison is made with the
internally generated payload information and the VD_STD_ERR bit is not set HIGH.
NOTE 1: If the received SMPTE 352M packet indicates 25, 30 or 29.97PsF formats, the
device only indicates an error when the video format is actually progressive. The device
detects 24 and 23.98PsF video standards and perform error checking at these rates.
NOTE 2: The VD_STD_ERR bit should be ignored in all 3G modes.
NOTE 3: VD_STD_ERR_DS1 is set incorrectly for a 1920x1080/PsF/24 payload ID. To
resolve this issue, choose one of the two methods.
• Set the VD_STD_ERR_DS1 mask bit high in the ERROR_MASK_1 register to avoid
having incorrect assertion of the DATA_ERROR pin.
• Monitor the received SMPTE ST0352 packet in the VIDEO_FORMAT_352_A_1 and
VIDEO_FORMAT_352_B_1 registers and compare that to the video format
identified in the VD_STD_DS1 bits in the DATA_FORMAT_DS1 register. Then, make
the determination of whether or not there is a mismatch on their own.
4.18 Signal Processing
In addition to error detection and indication, the GS2970 can also correct errors,
inserting corrected code words, checksums and CRC values into the data stream.
The following processing can be performed by the GS2970:
1. TRS error correction and insertion.
2. HD line based CRC correction and insertion.
3. EDH CRC error correction and insertion.
4. HD line number error correction and insertion.
5. Illegal code re-mapping.
GS2970 3Gb/s, HD, SD SDI Receiver Complete with
SMPTE Audio and Video Processing
Data Sheet
47478 - 4
September 2012
69 of 145