Using the Plex player with Roku sometimes shows flicker/stuttering/jitter (low frame rate)
I like to download Vimeo files from a subscription source to my Windows 8.1 computer, then play them from my Roku, which is connected to a non-smart Samsung TV. The videos show a man lecturing.
Usually the videos play nicely, with a high frame rate and good resolution. Sometimes (at random times, usually in the morning) there is a low frame rate, which makes the video seem to jitter when displaying a person moving an arm or a head. The jitter is very even, so it looks like it is skipping every other frame. It looks like very slow animation. I'm no expert in the proper terms to use.
If I stop the video using the Roku and restart the video playback, the jitter is still there. If I stop the video and navigate to an onscreen button consiting of three vertical lines and click it, I get a Settings screen. Under Playback > Quality it says 1.5 Mbps 576p ((Original). If I change this to 1.5 Mbps 480p and continue playing the video, The jitter is gone, but the picture looks fuzzy, like it is out of focus.
When I use Plex Player on my computer, the frame rate is quite low, but I don't see separate frames when people move their arms.
If I play the same video on Microsoft Media Player, motion of an arm is blurred. If I play it with SMPlayer, it looks great, with no problems.
When I download videos, I am given the choice of resolution. I use the Video Download Helper Firefox addon and usually choose 960x540 (sometimes 640x360 if 960 is not available). This keeps my disk files a reasonable size.
Am I doing something wrong, or is there some setup that I am not doing right? I could not find this problem online or in the Plex help system.
Windows 8.1 (home)
Roku Streaming Stick (latest update)