I think I've pretty much narrowed the problem down to all files in the MXF wrapper. Doesn't matter if HD or 4K, if it's MXF, it stutters badly at startup. HD files continue to drop frames throughout playback, whereas the 4K stuff seems not to drop additional frames after the initial startup lag is cleared. I've tried upping the priority all the way to Realtime, but no improvement. Tried limiting Premiere to 4 physical cores (processor affinity) and it seemed to do slightly better on frames dropped. Below 4 cores, it starts to have difficulty maintaining frame rate. I've played with the sound card ASIO settings, increasing and decreasing the buffer. Right now it's at 6mS. I had a real double eye-opener in the past two days though; one was VLC Media player, when set up to use more than 1 thread, runs circles around Premiere in terms of ability to effortlessly play the MXF wrapped 4K footage. Even the 59.94FPS long-GOP FS7 footage I tested with, smooth and only 6% CPU usage. With 24FPS, CPU use is 2%. In Premiere, it's 16% and dropping frames now and then. 36 frames dropped over 18 minutes play of 4K material. The other eye-opener was DaVinci Resolve 12 beta. Holy smokes! It plays 4K footage like it's DV, and even four camera angles in multicamera plays at nearly full frame rate and at full resolution. The only thing that Resolve does poorly is render. It renders at about 2FPS. It's always something! Premiere renders at about 80FPS on this system. Scrubbing the timeline is smooth, too. It's just the play that's screwed up. It's as if the timebase that Premiere is using for steady play rate is losing communication with the API. But again, this only happens with MXF wrapped files. I need to try that benchmark again, after killing the Quicktime service. I'll report results when I can. Thanks for the advise on solving that unknown error with the benchmark.
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