For owners of the SM-G9750 (S10+ CN / HK model), I'm trying to get some verification here on a possible software issue. I'm trying to play a 4K video file locally (specifically a 4K HDR x265 / HEVC MKV @ 30fps video, but I believe this bug may apply to all UHD video playback - I'm not sure as I haven't done enough testing) and it seems to be dropping frames and stuttering throughout. I cannot get it to play smoothly despite trying all of the following:

• Setting the phone to Performance mode.
  
  
• Trying different players - in this case, the default video player, MX Player Pro and VLC.
  
  
• Moving the video player app to Game Launcher and optimizing them for performance.
  
  
• Forced 2D GPU Rendering in Developer Options.
  
  
• Changing display resolution from WQHD to FHD.
  
  
• Moving the video file from SD card to internal storage.
  
  
• Disabling / uninstalling all apps which use Accessibility Services.
  
  
• Clearing cache.
  
  
• Factory reset.
  

None of these worked. ---UNTIL--- I tried using the screen recorder, from the Game Launcher settings, whilst watching the video. Playback was then perfect! No dropped frames, completely smooth, like it should be. The other alternative was to use software decoding but then colours would appear muted and battery life takes a huge hit.

So what's the deal here? Is the CPU or GPU not kicking in / being throttled whenever I launch a video player app? I'm assuming this is the case as the screen recorder seems to boost playback performance once I activate it. I'm on the June update and I'm not sure if this bug was introduced recently (I never tested 4K playback until now).

Owners of this particular model, could you please confirm if you are having this issue? Try watching a 4K video with lots of action and camera panning movements - that's where you can detect dropped frames or stuttering easily. I could provide the file I'm using for reference but it's a clip from a movie and I'm not sure if I'm allowed to share it here.

 

Try this clip for example, it's 4K HDR encoded in H.265 / HEVC, I don't know if that makes a difference:

http://www.mediafire.com/file/m83ftn7n8d8le2s/Plane_Crash_Scene.mp4/file

Stutters in the default video player app for me. One thing to note is that it's smooth in portrait mode, but the moment you rotate into landscape fullscreen, it starts dropping frames. Now, turn on the screen recorder from within game tools and the stutters are mostly eliminated. What gives?

Another way to compare would be with a video player that lets you switch between hardware and software decoding, like MX Player. Watch the clip in HW mode and then switch to SW - it's choppier in HW mode for whatever reason. Using SW is not an option as the colours are not displayed properly and battery drain is much higher.

Regarding the clip - if it's against the rules to post such content, let me know and I'll remove it. There's a whole YouTube channel full of this stuff, I don't want to link to those as the problem I'm encountering is related to local video playback.

 

One last try before I sign off Here's another example if anyone has YouTube Vanced (google vanced.app for those unaware). I'm suggesting Vanced because the original YouTube app doesn't let you view at 4K resolution.

• Firstly, open Vanced and tap the account icon in the upper right. Go to settings, Vanced settings, Video settings and then toggle Resolution Checks to ON. Refresh and restart the app.

• Now open Game Launcher, tap the three dots in the upper right > Add apps and add YouTube Vanced to the list. We're doing this for the screen recording function which I'll mention later.

Once that's done, here's a 4K 60fps clip for you to try. It should be easier to perceive any hiccups with the higher frame rate. And of course, please set the resolution to 2160p (tap the three dots in the upper right) and watch in landscape orientation, since this is what the test is all about:



Panning shots work best. For reference, see the one of the step trail at 2:42 in the video. Does it look like it's stuttering or dropping frames intermittently?

• Now, swipe up from the bottom of the screen to show the navigation bar (you need the navigation bar enabled to use the recording function) and tap on Game Tools, which is the leftmost button. Tap Record.

While the screen is recording, are the stutters now gone? To my eyes, the video is definitely smoother while the recorder is active. Appreciate any feedback from those willing to try (and confirm if I'm insane or not!) - cheers!