The Video Source Block contains Test Pattern Generator (TPG), Interlacer IP, and CVO IP. This video source block is used to generate difference type of video formats, which include PAL (SD-SDI), 720p60 (HD-SDI) and 1080p60 (3G-SDI).
The CVO IP is configuring to three difference video models by using the “video_format.tcl”. The CVO IP will detect the incoming video format and switch the video model accordingly.
Model 1: 720p60
Model 2: 1080p60
Model 3: PAL
The CVO’s vid_clk is connected to SDI’s “tx_clkout” when transmit 3G-SDI, for other video formats, the CVO’s vid_clk is connected to “tx_dataout_valid”.
Please take note that the “vid_clk” is not glitch-free in this design, and above connection of "vid_clk" is not recommended for the production.
The “vid_std” signal is an output signal of the CVO, it output the value (e.g SD-SDI = 0, HD-SDI = 1 and 3G-SDI =3) that you configure at Model Standard Register of CVO (address 12), and this signal can be connected to SDI IP (tx_std signal).