PVD123 wrote: ↑Wed May 19, 2021 16:48
I'm looking to put together a system that can ingest (4) 1080p video feeds via HDSDI and output (1) 4k 12G SDI and (3) 1080p on HDSDI. Latency on that video input is a big deal. It will be live in the venue, so delayed video will get ugly fast. I would like to stay in the pro video world, so HDMI and Display port are not super attractive. Thanks in advance for your input!
Have studied this problem in another context, unrelated to Resolume. Minimizing latency in IMAG is not difficult. It does require effort to measure the glass-to-SDI output latency in your video cameras. Many years ago, the “industrial” grade of cameras from the likes of Sony, Panasonic, etc. had 3-4 frames of latency! And, cinema cameras like the RED ONE had up to 5-6 frames of latency! It was bonkers! To get 1-frame of latency, for IMAG applications, from Sony or Panasonic required spending big bucks on their higher-end “broadcast” grade cameras, rather than the mid-grade “industrial” cameras. Blackmagic upset the business strategy of the big two with the URSA Broadcast camera, which does feature a 1080i59.94 output with 1-frame of latency. 1080i sounded bad until I realized that broadcast vision mixers are optimized for the lowest delay with 1080i, as are many, many projectors. So, the combination of a 1080i output from a camera, into something like an Analog Way Ascender 16 (or whatever), 1080i, into Barco projectors, 1080i, has basically <2 frame delay. Assuming all the cameras are genlocked. It’s <2 frames. End to end. Incredible.
To achieve that in software is hard. Here is why. A typical SDI input board on a computer is going to have 60ms (i.e. - nearly four frames) of input delay. Then, if you want to use SDI out, you’re going to add even more delay. I don’t remember the exact numbers for that. I think usually about another 60ms (i.e. - nearly four frames). So, it’s hard.
And, that’s on top of your cameras! And, in addition to your projectors or video wall processors!
For lowest delay, this requires using genlocked low-latency cameras and a zero-latency vision mixer.