Open Bug 1461266 Opened 6 years ago Updated 2 years ago

comments framerate is smoother on Chrome than Firefox

Categories

(Core :: Graphics: Canvas2D, defect, P3)

Product:
Core
Component:
Graphics: Canvas2D
Version:
57 Branch
Platform:
Unspecified
macOS
Type:
defect

Tracking

()

People

(Reporter: karlcow, Unassigned)

References

(
URL
)

Details

(Whiteboard: [webcompat]) 

With Firefox Nightly 62.0a1 (2018-05-13) (64-bit)
and Chrome Canary Version 68.0.3429.0 (Build officiel) canary (64 bits)


1. Open http://www.nicovideo.jp/watch/sm31927805
2. Advance Firefox to 5s.
3. Start the video on Chrome Canary
4. When it reaches 5s, start the video on Firefox. (so both videos are mostly synchronized)

Actual:
Comments passing on the screen on Firefox is janky. Very smooth on Chrome.
Can confirm...

This is a 24fps video. On Firefox it's very janky, particularly noticeable on the scrolling text. The judder on the text is pretty bad.

My guess is that this bug should be lodged under the graphics components as the media stack gives all the frames to be displayed to the compositor, and it's up to the compositor to render them properly.

Matt, any suggestions?
Component: Audio/Video → Audio/Video: Playback
Flags: needinfo?(matt.woodrow)
Looks like the comments are drawn using a <canvas>. We're definitely pushing 60fps (easily), so maybe we're snapping text to pixels and making it look jumpy?

I had a quick look in a debugger and it looked like we were trying to support subpixel positioning at least.
Component: Audio/Video: Playback → Canvas: 2D
Flags: needinfo?(matt.woodrow) → needinfo?(lsalzman)
It's definitely not text, as the way this is scrolling the text is by first rendering them into images, and then just drawing those image to the canvas repeatedly, which seems to be where it is getting bottlenecked.
Flags: needinfo?(lsalzman)

Migrating Webcompat whiteboard priorities to project flags. See bug 1547409.

Webcompat Priority: --- → ?

See bug 1547409. Migrating whiteboard priority tags to program flags.

Webcompat Priority: ? → ---

reason of this bug is, in Firefox, HTMLMediaElement.currentTime update rates are near 25fps in Firefox. but in Chrome and Safari, it will updates constantly (>60fps).

currently www.nicovideo.jp including workaround for this and can't reproduce bug now, but embed.nicovideo.jp not using workaround, so you can still see old behaviour in embed.nicovideo.jp.

e.g. https://embed.nicovideo.jp/watch/sm9

Severity: normal → S3
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