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Comment by arghwhat | Hacker News Reader

Do you modeset your monitor to 24Hz when you watch a movie or a video? Do you remember to change between 24 Hz and 29.97 Hz?

The solution to this is higher refresh rate and/or VRR.

VRR would allow you to sync to any needed timing (regardless of VRR range, as multiples of fps are fine), dynamically, with no need to modeset to fixed supported refresh rates.

120Hz not only happens to be a multiple of both 24 and 30, but judder from such low framerate input becomes irrelevant at these rates, with VRR instead serving high-framerate content that is slightly out of phase.

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That's one of the main reasons to use a media center. Kodi will do that. Jellyfin for AndroidTV will do that.

Others like VLC only do motion interpolation, and some work is ongoing for VRR support (notably, AMD GPUs on Linux, but they work with Low Framerate Compensation so it's conside red hacky and with a higher power draw).

Of course, higher refresh rates are better, but it's quite wasteful anyway if you only have a 24 FPS. Moreover, not evvery mode is a multiple of that.

> Low Framerate Compensation so it's considered hacky and with a higher power draw

This is not hacky or has higher power draw - the display has a minimum refresh rate, and sudden large changes in refresh rate can lead to visible flickering.

The GPU and driver is required to handle this. The alternative is much more intelligent display controllers than is currently available anywhere, so the CRTC lives in the display and just receives framebuffer content whenever.

> Of course, higher refresh rates are better, but it's quite wasteful

It is negligible. Your GPU will do nothing most frames, and the panel power consumption comes from backlight.

> Moreover, not every mode is a multiple of that

Slow framerates do not need to be a multiple of high framerates, as the error becomes irrelevant.

VRR is the solution for fine-tuning for perfectionism.

> This is not hacky or has higher power draw - the display has a minimum refresh rate, and sudden large changes in refresh rate can lead to visible flickering.

I get that[1]. It's a shame we can't specify next frame latency as well, it should be fairly predictable for video (or enable triple-buffering on the monitor side).

> It is negligible. Your GPU will do nothing most frames, and the panel power consumption comes from backlight.

I was basing this on a recent patchset with the following quote[2]:

> Enabling this feature also have the potential side effect of causing higher power consumption due to running a mode with lower resolution and base clock frequency with the highest base clock supported on the monitor as per its advertised modes

[1]: https://github.com/swaywm/wlroots/issues/1406#issuecomment-4... [2]: https://www.phoronix.com/scan.php?page=news_item&px=AMDGPU-F...

You don't have to with freesync monitors, they can dynamically lower.

FreeSync is VRR, which was already mentioned. Same goes for G-Sync.

There is always 3:2 pulldown too.

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