Some time ago I started a thread about VLC player alternatives. Because of stuttering problems. I finally installed a new one today from the ones you suggested, Pot Player. Unfortunately it suffered from the same issue, so obviously the problem lies somewhere else.

Started last year. Back then it would be a single stutter every 5-10 seconds. Nothing major. Since then it's gotten worse. The videos basically suffer from mild to sever stuttering. At times as if completely in slow motion.
Back when it started I noticed that switching off Corsair Utility Engine (CUE), my keyboard's control panel, fixes it. Nowdays, if switching off CUE has any effect, it's negligible.

Symptoms:
_ Not sure what triggers it. I have the PC on all time, even at night.
_ If it starts happening it will continue, until the machine is restarted.
_ Restarting often fixes it but sometimes doesn't. I think shutting it down completely, then starting it again is more effective than restarting, but I'm not sure.
_ Happens with many different files, file formats and codecs.
_ Never happens with Windows Media Player. Happens with VLC media player and Pot player.

Due to its random nature, it's a bit difficult to diagnose...

Any suggestions on what could be causing this? Or how do I go about diagnosing it?

Thanks.

Well, know its totally unpopular nowadays, but just shut the machine down when your not using it. This allows for cleaning. Run a malware and virus scan regularly. Install everything outside windows folders. Manually clean all folders like user areas, temp, program data. Keep minimal things installed. Etc.

Windows can do some strange things at times,me I'd start to clean it up a bit and see if it remains.Sometimes the simplistic programs are the best.

Question ZFR. What kind of videos?

Hear me out and I'll explain. A number of videos are encoded with the new h264 codec, nothing wrong with that. However there's something like 80 features used in the codec. When the Mpeg4 standard was out which included all of those as part of the standard, some people said it would be too hard to do, and instead picked out certain pieces they thought was more useful. This is where the DivX, Project Mayo and other MP4 encoders came from, that they were using a select number of a larger inclusive codec.

Now the AVC (Advanced Video Codec) has some certain features which can be very CPU intensive. This includes like looking back something like 16 frames of memory. Now if you have less than say 2 Gigs of free memory, this means that it might discard previous images, then have to re-decode older images in order to decode a current image, because it's using that particular feature.

x264 and other codecs have an option of a zero-decode cost where those things are disabled, but that is only for what you're encoding, not for what's already encoded. If you download or get a MP4 video that has some of the advanced features enabled that require intense CPU work, you will get stuttering, or video de-syncing with audio, or other issues.

So. For a video in particular, can you get the meta data of how it was encoded? Perhaps that will tell you more, and whether it will work at all for you or not. Because I know some video cards can decode MP4, and when they do it's far faster and simpler than when I had to fight with and get new video cards and recode the video in order to watch clips where my computer couldn't keep up.


edit: And thinking about it since it seems to happen elsewhere randomly with other files/codecs, I'd suggest opening Task Manager and setting the priority of the video player to above Normal, or higher. That might take away the problems until the player is closed.

Other than shutting down when not using, check on everything else. I've tested with dozens of different ones. And as I said, if Windows Media Player can run them, they don't stutter, while they do stutter on VLC/Pot.
When it does stutter, it stutters on all videos.

I have 32 GB RAM. Intel i7 4790 4.00GHz processor. It really shouldn't have problems playing those videos.
EDIT: 32, not 16 GB RAM.

Those specs you probably shouldn't have any issues except like 2k/4k video

Hmmm... Aside from giving the player priority, and maybe disabling Aero or other eyecandy, not sure what else to recommend.

Although i'm suddenly reminded. One streamer has a lot of frame drops and performance penalty when his Windows 10 updater is in the background downloading, or seeding the uploads to other computers. So... check on that too.

Some combinations of GPU drivers and player software work better with Aero off, but nowadays most work better with Aero on. While you can try switching Aero off it's generally better to leave it on.

As rtcvb32 already said make sure there is nothing running in the background.

If you have made certain that no other software is using the CPU, GPU or hard drive there might be a problem with either the CPU or the GPU or a defective fan that causes one of them to overheat when it is excessively used. If one of the players uses hardware decoding on the GPU and the other player doesn't that would explain why two players show different behaviour.

Try to find the setting for hardware decoding in the player and try changing it. Set it to hardware if it was on software or the other way round and see if that changes anything.

For further diagnosis get MSI Afterburner. That's an awesome piece of software that let's you monitor CPU and GPU usage and temperature in real time. When the video stuttering happens next time check if usage or temperature are unusually high.

Try switching from the default video output to specifying it yourself. Choose either DirectX or OpenGL and then restart the player after saving settings. If it still stutters, try the opposite output and restart again.

You may want to explore changing the size of certain buffers in advanced settings also, but only after searching the web for information on how to set them correctly as randomly changing things on a whim can result in more problems than solutions.

The trick of changing the output to OpenGL or whatever can work around other problems that crop up also such as spurious green lines on the bottom or side of a given video.

Thanks for the replies all. Sorry for not responding, but since this happens randomly, I can't test it any time I want, especially when busy with work.

Well, it's happening now, and I have some free time, so I'll take a look at what you posted.

One thing found out so far; the problem is definitely with the video and not audio. If I disable the video channel, the audio itself plays smoothly, while if I disable the audio channel, the video still stutters (though it's a bit difficult to tell, as it's the sound stuttering that makes it obvious).

Hmmm. Out of curiosity, do you have multiple monitors set up? And if so, are they to the same video card or different video cards? (I'll assume no, but still curious to know)

Another thought coming to mind is there's an option for post-processing in VLC which you can disable, basically it's cleanup after mp4 after decoding to make it look nicer, however that doesn't really sound like the problem you're having.

Next:


No changes in CPU/GPU temperatures when running. CPUs are around 38-40C while GPU is 42-44C. Both when a stuttering video is running and idle.

Enabling/Disabling hardware accelerated video output in VLC has no effect.
No.

OK, some progress:

Heavy stuttering when using:
_Direct3D
_DirectX (DirectDraw)

Very light stuttering (but still noticeable, like 1 stutter every few secs) when using:
_OpenGL
_Direct2D

No stutter when using:
_Windows GDI
but... when I open some high resolution videos using Windows GDI I get some colour artefacts on screen. I imagine this is what Windows Media player uses, since it has no stutter on most files, and doesn't open the high resolution videos that produce artefacts when running on VLC.

So... any advice on how to proceed from here?

EDIT:
Not sure I mentioned this before, but using Windows 7, GeForce GTX 970 graphics card.
DirectX diagnostic tool shows no problems.

For a second I thought this thread was about the Nintendo Switch.