Hi Johnson,
As I understand it, you have some inquiries related to using 12G SDI with CVI II. For your information, you may try to refer to the following A10 example design with 12G SDI and CVI II to see if it is helpful:
https://fpgacloud.intel.com/devstore/platform/19.2.0/Pro/intel-arria-10-gx-device-multi-rate-sdi-ii-pass-through-using-video-image-processing-pipeline-reference-design/
This design is created for A10 device but there should be no problem to port over to C10GX device.
Please let me know if there is any concern. Thank you.
Best regards,
Chee Pin