SDI with Clocked Video In/Out - How to go from 10 bits to 8 bits color depth???

Altera_Forum · ‎05-10-2014

Hi

I have 4 SDI video interfaces (two in and two out) in my project. I will be using Altera’s SDI II IP core. As you may know that the core de-serializes the input HD-SDI into 20-bit YCB/YCr data (10bits/color).

My project is currently setup as the following which includes Altera’s VIP cores:

SDI Core Rx -> CVI -> DEINTERLACER -> CLIPPER+SCALER -> FR BUFFER -> CVO -> SDI Core Tx

Due to memory bandwidth and resource limitation, I want to reduce the color depth from 10bits to 8bits for the SDI interface when passing the avalon stream through the VIP cores. My question is how do I go about achieving this?

I was thinking of adding simple pass-through block after CVI where I just truncate the 2 LSBs from each color space (e.g. [19:10] -> [15:8]=[19:12], [9:0] ->[7:0]= [9:2]). Then add similar block at output side just before CVO where color spaces are stuffed with two zeros for each color space. Do you think this approach will work?

Any suggestion is much appreciated!

Altera_Forum · ‎10-13-2014

For those with the same questions, here's what I found out: you can directly connect the SDI II rx core databus to 8-bit/color plane CVI block by simply using SDI [19:12] -> CVI [15:8] and SDI [9:2] ->CVI [7:0]. No need to use CSC to convert to 8-bit colour system.