VRR for video playback (video players, web browsers, etc.)

[psycho]

I finally got a VRR monitor for myself and I'm loving it. I'm a person who would always be fiddling with monitor's refresh rate to match the fps of whatever I was doing (gaming, video playback, etc.) and finally I don't need to do that for games anymore. However, for video playback that is not as straight forward, especially on the web browser and/or streaming side of things. Native video players exist that support VRR, others support automatical refresh rate change based on the video's fps, but no web browser / streaming app that I know of support VRR.

Sadly I am not a developer, but I have prepared argumentation of why web browsers and streaming service apps should consider supporting VRR:

Advantages of VRR for Video Playback

Handling Mismatched Frame Rates:
Many modern monitors have high refresh rates (e.g., 144Hz), which work well for frame rates like 24fps, 48fps, or 72fps but cause issues with non-matching rates like 30fps or 60fps due to uneven frame delivery.
With VRR, the display's refresh rate can dynamically match the frame rate of the content or its multiples (e.g., doubling 24fps to 48fps to avoid flicker and maintain compatibility).

Avoiding Display Judder:
Non-integer frame rate matching often leads to judder, where frames are repeated inconsistently. VRR eliminates the need for such compromises by syncing frame presentation directly to the monitor.

Web Browser and Player Integration:
Web-based video playback (e.g., YouTube) often operates in environments where the refresh rate is fixed at the monitor’s maximum. Enabling VRR would allow browsers to adjust refresh dynamically, offering smooth playback for diverse content. I am watching YouTube videos that are sometimes 24, 25, 30, 50, 60 fps and without VRR I would need a 600 Hz refresh rate to display them all smoothly, with VRR no such high refresh rate would be needed.

Challenges and Workarounds

Low Frame Rate Limitations in VRR:
Many VRR monitors do not support very low frame rates (e.g., 24fps). A good workaround is to use frame rate doubling or tripling, e.g., presenting 24fps video at 48Hz or 72Hz within the VRR range.
Players should implement logic to always match at least a double or triple multiple of the source frame rate.

Audio Sync:
Adjusting the refresh rate dynamically may cause timing mismatches with audio playback. This requires careful synchronization mechanisms in the player. However, this might not be a real issue at all, since video fps is suppsed to be constant.

Web Browser and System Integration:
Browsers and operating systems must expose APIs for VRR control.

Limited Standardization:
Different monitors and GPU drivers handle VRR slightly differently, making a one-size-fits-all solution difficult. Developing a robust VRR implementation would need careful testing across a range of hardware.

Implementation Proposal

Web Browser Support:
Browsers like Chrome, Firefox, and Edge could expose VRR controls to web apps, allowing YouTube and other streaming services to utilize VRR for smoother playback.

System APIs for VRR:
Platforms like Windows, macOS, and Linux should allow finer VRR control for media playback applications, enabling smooth transitions between different refresh rates.

Monitor-Specific Optimizations:
Monitor manufacturers could expand VRR ranges downward (e.g., below 30Hz) or implement features like frame-doubling internally to support smooth playback of low frame rate content.

Potential Projects and Future Work

Custom VRR Video Playback Pipelines:
Developers could create web browser extensions and open-source plugins or patches for existing players like MPV or VLC to experiment with VRR for video playback.

VRR Middleware:
Middleware software could act as a bridge between the player and display, dynamically adjusting refresh rates as needed.

Collaborations with Hardware Vendors:
Teams working on VRR video playback could collaborate with GPU and monitor manufacturers to optimize the technology specifically for media playback scenarios.

Suggestion to set VRR to a double or multiple of the frame rate is particularly compelling, as it ensures smooth playback even on monitors with limited VRR ranges. This approach would make VRR adoption for video playback not only feasible but also highly practical for both desktop applications and streaming platforms.

So, in conclusion... I would love to see the same attention that gaming on VRR has paid to video playback on VRR so we can forget fiddling with monitor's refresh rates for an always smooth video playback, no matter the fps of the video.

[Dalek]

I remember trying 360hz and noticing how jittery youtube videos were and in VLC. So 600hz will be the solution for 30/50/60FPS content to look normal?

If that's the case, it won't be too long until we reach 600hz. Maybe another year or two.

I still find it surprising that this is still an issue in general given how much popular high refresh rates have become in recent years.

[psycho]

As I said before, I am not a developer, but to me it's surprising that on the one hand we have:
- a video player (mpv) which works exactly as I would expect for a VRR aware video player to work. I tested the x86_64-20241205-git-91f1f4f version if anyone is interested
- TestUFO web browser based tests, where everything is super smooth although it's all simulated

and on the other hand:
- no other video players that I can find have VRR support yet (there are a lot that are based on mpv, so I don't count those), the best alternative that they offer is changing the refresh rate based on the fps of the video, which is sub-optimal, since you can sometimes lose the audio stream in that process and to be honest it "feels" worse than when no refresh rate change is needed
- there is no web browser extensions that would add VRR video player functionality

Having mpv is totally enough, don't get me wrong, I just can't help but wonder why there is only one so far.
Having nothing on the web browser side is making me sad... and I hope I'm not too annoying when I address Chief Blur Buster directly to ask his opinion on how hard it would be to code a web browser extension for VRR video playback and maybe even if he would wish to code it.

[Pontan_¤03]

From my experience, VRR doesn’t really add much for normal video playback. Movies and shows are usually fixed frame rates (24, 30, 60), so a decent player and proper refresh rate matching already give smooth playback. I’ve tried VRR on and off in browsers and players, and the difference is basically invisible unless there’s badly encoded content or frame drops.Where VRR can help a bit is with weird web videos or mixed refresh scenarios, but it can also cause brightness flicker on some panels. About www.movavi, I’ve mostly seen it mentioned in driver notes or display settings discussions. In practice, it’s more relevant for gaming than everyday video watching.

[Chief Blur Buster]

From my experience, VRR doesn’t really add much for normal video playback. Movies and shows are usually fixed frame rates (24, 30, 60), so a decent player and proper refresh rate matching already give smooth playback. I’ve tried VRR on and off in browsers and players, and the difference is basically invisible unless there’s badly encoded content or frame drops.

You need a fully VRR-aware movie player.

Most players & web browsers are not VRR aware.

In other words, less than 5% of video player software are VRR aware and can smooth playback.

That being said, it is indeed much more reliable to configure your refresh rate to a number like 120 to be universal for most content.

[William Sokol Erhard]

To be clear, like op said, MPV does fully support VRR.

I think yt-dlp fulfills what you're looking for as far as web video support. Anything on this list can be loaded into MPV via yt-dlp:
https://github.com/yt-dlp/yt-dlp/blob/m ... edsites.md

I built my Vint software on top of MPV and yt-dlp and I have helpful functions to make playing web videos back through this with VRR support in addition to Vint's BFI and ultra high quality interpolation functions. For example, if you copy a video link and right click on the Vint icon, it will automatically open a window with that video in MPV with all of Vint's processing.

I think Dalek's issues with youtube videos on a 360Hz (OLED?) are due to what RTINGS calls "response time stutter": https://www.rtings.com/tv/learn/motion-plan

The only way to address that issue is to watch higher framerate videos or process the video itself with interpolation. BFI can help as well but you're trading choppiness with flicker while at low framerates like 24fps. BFI and other types of strobing work best with a higher than 60fps signal. Vint's interpolation however works great with 24fps or lower content.