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Re: pg258q 240Hz video playback microstutter problem

Posted: 09 Nov 2017, 13:05
by Chief Blur Buster
knypol wrote:Stutters only in web videos (netflix and youtube). In Home Media Player everything looks ok. Ive just tested Netflix app for PC on windows store which has an option for offline watching. I downloaded movie and still very choppy. Movies even lose synchronisation between picture and sound. Overall it isnt that much of a problem because i can use windows desktop in 120Hz and launching games in 240Hz but..im just curious what is the reason.
I have figured out another cause why 24fps or 60fps sometimes stutter more at 240Hz than 120Hz, despite being evenly divisible.

Many players will round-off more often to adjacent refresh cycles if the refresh-cycle-granularity is small enough.

Decoding fluctuations (e.g. video frame processing jitters by 5ms) will easily round-off properly at 120Hz (8.3ms refresh cycles) or at 60Hz (16.7ms refresh cycles) but may cause microstutters at 240Hz (4.1ms refresh cycles) since the refresh cycle is shorter than the processing/decoding fluctuations.

More powerful CPUs, more powerful GPUs, better players, high-precision clocks, all reduce "fixed-refresh-rounding-off-error" microstutters.

Possible solutions
--> Increase the framebuffer rendering queue to 2 or 3 (e.g. NVInspector). This adds input lag for games, but might cause certain video players (Netflix App) to play smoother.
--> Another solution is get variable refresh rate display, and instead play in VRR mode using a VRR-compatible player such as SMPlayer. This avoids the "fixed-refresh-rounding-off-error" microstutters. This works for downloaded files (.MKV .MP4 etc)