@dusxFurther observations...Smooth video output gets a little bit better if I decrease the service task rate to 1x. (What would be an actual reason to have it above 1x? I haven't found any documentation that further describes this.)Now that I have reasonably glitch-free SDI output, differences between (low-load, realtime-capable) GLSL shader generated content, and pre-rendered movie files become more apparent. The GLSL stuff outputs fine most of the time, in fact I'd say it's now better than the computer monitor outputs (no tearing, mostly no frame doubling or frame skipping). Pre-rendered files (say, Prores422) tend to have more difficulties. Playing movie files, here's what I see at different frame rate combinations. All based on Prores422 1920x1080 files, with the movie player using the AV Foundation playback engine:- low frame rates (24/30): irregular SDI frame skips are extremely rare. However, every now and again the movie player seems to get caught in a situation where the playback judders pretty regularly. When that happens, it usually starts when the movie begins playing and often only clears once the clip ends and goes to repeat. Pausing and unpausing, or stopping and restarting the clip, mostly clears the problem. That goes the other way too: If playback is fine at any given moment, and I pause/unpause the video a number of times, I'm very likely to reproduce the problem without waiting for the clip to repeat. Turning SDI output off and on for this particular issue doesn't clear the glitches, it very probably lies more closely with the movie player. The issue is FAR more frequent on 1080p24 movies, and more visible, than 1080p30.- 1080p60 file with Isadora operating in 30fps: irregular SDI frame skips happen a little more often, maybe on average roughly every 30 seconds or so.- 1080p60 with Isadora operating in 60fps: irregular SDI frame skips happen quite frequently, at least once every 10 seconds.That's about as far as I can trace the choppiness for now. Based on the findings so far, currently my strategy would be to run everything as 30fps (not 24, not 60), hoping I don't have to integrate pre-existing fast-motion content that's already 24 or 25fps.Guess I should still test 25fps operation.