1371999 - Downscaled videos look extremely bad with pronounced aliasing artifacts

Status: RESOLVED WORKSFORME

(Core :: Graphics, defect, P3)

Description

[avada]

Attachment: UHD video downscaled on youtube.

Title says it all. See attachment for a screenshot of a UHD video downscaled on youtube.

Comment 1

[avada]

Well, this remained unacknowledged...

By the way I have an Nvidia GPU, in case downscaling quality is dependent on driver/manufacturer.

I remember from testing with progDVB that with EVR only Intel did downscaling properly, on Nvidia and AMD based platforms downscaled images looked horribly aliased.

Comment 2

[Anthony Jones (:ajones, :kentuckyfriedtakahe, :k17e)]

(In reply to avada from comment #1)
> Well, this remained unacknowledged...

That is because I'm fairly busy. Does this happen by default on YouTube or only when you manually select a resolution higher than what YouTube is selecting for you?

Comment 3

[avada]

(In reply to Anthony Jones (:kentuckyfriedtakahe, :k17e) from comment #2)
> 
> That is because I'm fairly busy. Does this happen by default on YouTube or
> only when you manually select a resolution higher than what YouTube is
> selecting for you?

The latter. But Youtube is not everything. Many resolutions might not always be available.

Comment 4

[Lazy Monkey]

see also this discussion:
https://www.reddit.com/r/firefox/comments/usy9av/firefox_has_aliasing_and_shimmering_in/

Comment 5

[Animesh Bhattacharya [:AnimeshB]]

Attachment: Downscaling comparison between Firefox and Edge/Chrome

Aliasing is noticeable with a 4K video on Firefox when not fullscreen on my 1080p display in YouTube's 720p viewport.

It should be noted that I've found the same issue even if I use Ctrl+O to play a 4K video (zoomed out to 30% to reduce the size of the video), so it's probably not YouTube related, but how Firefox displays videos. Edge and Chrome downscale correctly in when using their Ctrl+O shortcut to open the same video.

I'm using Firefox 100.0.1, on a desktop with an Nvidia RTX 2060, Intel i5 10400F, and Windows 11. I've also replicated this issue on a laptop with an AMD Ryzen 5 4600H, GTX 1650 Ti and Windows 11, also with Firefox 100.0.1. Both were tested with all default settings and no addons. Hope this helps.

Comment 6

[Animesh Bhattacharya [:AnimeshB]]

Attachment: Downscaling comparison using built in video player

The aliasing issue persists even when using Firefox's built in video player to play the same 4K video. This screenshot was taken by using Windows' split screen window function, which made the scaling issues more prominent.

Comment 7

[Kyle Barr]

I wanted to add to this since I actually moved to Firefox for this specific feature, or I guess bug in this case. The lack of scaling made videos look better, at least ones that were 1080p or 1440p on my 1080p display.

Chrome appears to use some sort of bilinear-like filter. While it does reducing aliasing, it actually does it so much that the video ends up looking blurry, even if 4K is selected. I switched from Chrome to Firefox solely because Twitch streams and high res YouTube videos on Chrome looked pretty blurry due to their scaling, especially since the video would not be fullscreen due to chat being open on Twitch. Also, I may be remembering this wrong, but Chrome even applied this filter to a fullscreen video that is 1440p or 4K, and frankly it looked worse than a 1080p video on Firefox.

So I will say: If this bug is fixed so there is some scaling filter for video content, that it at least be one like Bicubic or Lanczos that provide improved sharpening. Or even better: make it an option so the user can select how they want their content scaled.

Comment 8

[Kelsey Gilbert [:jgilbert]]

@sotaro, any ideas on why/where this is happening?

Comment 9

[Kelsey Gilbert [:jgilbert]]

The video looks (too?) aliased in both Firefox and Chrome on my rx6700xt.

about:support:

HardwareStretching both=0 window-only=0 full-screen-only=2 none=0 error=0
OverlaySupport NV12=Scaling YUV2=None BGRA8=Software RGB10A2=None

Comment 10

[Bob Hood [:bhood]]

TexlGyTrail, can you attach your about:support data to this report, please?

Comment 11

[Animesh Bhattacharya [:AnimeshB]]

Attachment: about:support text data from Firefox 101.0.1, from my main desktop PC.

Comment 12

[Animesh Bhattacharya [:AnimeshB]]

Just added my about:support info, clearing needinfo request.

Comment 13

[Sotaro Ikeda [:sotaro]]

(In reply to Kelsey Gilbert [:jgilbert] (previously Jeff) from comment #8)

@sotaro, any ideas on why/where this is happening?

I am going to look into it.

Comment 14

[Sotaro Ikeda [:sotaro]]

https://www.youtube.com/watch?v=Y5D-4JyG2dA

I could reproduce the problem on my Win PC. With local chromium build, I tested when the problem did not happen with chromium.
With the following, the problem did not happen

• video overlay with RGB swap chain.

With the followings, the problem happened even with chromium.

• [1] disabling video overlay and SkiaRenderer::DrawYUVVideoQuad() did video rendering.
• [2] video overlay with YUV swap chain.

When the video played with chromium, video overlay was changed from YUV swap chain to RGB swap chain. Because fps of video was not high in SwapChainPresenter::GetSwapChainFormat().
https://source.chromium.org/chromium/chromium/src/+/main:ui/gl/swap_chain_presenter.cc;l=334

Comment 15

[Sotaro Ikeda [:sotaro]]

With gecko, when yuv swap chain is disabled, the problem did not happen with RGB swap chain video overlay on my Win PC.

It seems that video scaling to RGB swap chain with VideoProcessor has better quality than Video scaling to YUV with VideoProcessor.

Comment 16

[Brandon Karaca]

I noticed this issue on my computer today as well. The video I was watching looked particularly bad in picture in picture. I am able to help provide any info if needed. I am also wondering if there are any updates on when a better video scaler will be added to firefox.

Comment 17

[Sotaro Ikeda [:sotaro]]

Brandon Karaca, can you attach about:support to this bug? Thank you.

On Windows, RGB video overlay does better video scaling. Majority of cases, chromium also uses it for video rendering on Windows.

For now, with Firefox release, video overlay is supported only to hardware decoded video with intel gpu.
Video overlay support with non-Intel GPU of Firefox release was stopped by Bug 1787293 for now.

Then Bug 1798242 is going to check if we could enable video overlay without ZeroCopyNV12Texture with non-intel GPUs.
Bug 1753373 is going to enable video overlay for software decoded video if video overlay is already enabled and video frame data supports it.

Comment 18

[Brandon Karaca]

Attachment: Brandon Karaca - Firefox AboutSupport.txt

I have attached my about:support info.

Comment 19

[Sotaro Ikeda [:sotaro]]

(In reply to Brandon Karaca from comment #18)

I have attached my about:support info.

Thank you! On release channel, video overlay is not enabled yet on NVIDIA gpus. For now, we expects that video overlay usage improves video scaling quality.

Comment 20

[Sotaro Ikeda [:sotaro]]

Video overlay is enabled if possible. Close the bug for now.

Comment 21

[avada]

Attachment: Nightly 125.0a1 (2024-03-02)

I don't see a difference from when the bug was filed.

Comment 22

[avada]

Attachment: about:support data for the image above (125.0a1 (2024-03-02))