Bug 276717 – A crash with multiple video tags that contains webm source

• Component: Media
• Status: RESOLVED FIXED

[Dmitry Vakhnenko]

Created attachment 471904 [details]
Crush demo

For some reason a tab with multiple <video> tags crashes if it has a <source> in webm format.

We consistently catch this error on iPhone 12 only. On other devices we have not been able to catch this bug.

I have prepared a minimal example html file on which we catch this behavior.

[Dmitry Vakhnenko]

Hmm, on 13 iphone it crashes too

iOS 17.5.1

[Alexey Proskuryakov]

Thank you for the report! Perhaps it is just running out of memory? When opening on a Mac, I see the videos resize to become pretty huge.

Could you please see if there is a crash log stored? I don't have the configuration to quickly try it myself.

[Radar WebKit Bug Importer]

<rdar://problem/132405520>

[Jean-Yves Avenard [:jya]]

In this page we have videos with posters and have preload="metadata".

The webm player doesn't respect the preload="metadata" and so will download all the videos immediately.
They aren't particularly big here, 11.27MB, 74MB, 23MB, 5.6MB, 5.7MB and 11.8MB 

I haven't been able to reproduce on an iPhone running 21F90 (17.5.1) it takes forever to load but it doesn't crash.

Dmitry, can you make it crash with the test file attached on an iPhone 12 or 13? is is the attached example just to show what your page typically looks like and there could be much more videos present ?

A workaround for now would be to change 

```
					<video
						preload="metadata"
						class="videoPlayer"
						poster="https://optim.tildacdn.net/tild3162-3030-4635-b934-393766343537/-/format/webp/mike.png"
					>
						<source
							src="https://practicum-content.s3.us-west-1.amazonaws.com/usa-main/guidance/Tutors/2022_11_03_Videos%20of%20guidance%20team_Mike%20Lee.webm"
							type="video/webm"
						/>
						<source
							src="https://practicum-content.s3.us-west-1.amazonaws.com/us-videos/2022_11_03_Videos%20of%20guidance%20team_Mike%20Lee.mp4"
							type="video/mp4"
						/>
					</video>
```

into:
					<video
						preload="metadata"
						class="videoPlayer"
						poster="https://optim.tildacdn.net/tild3162-3030-4635-b934-393766343537/-/format/webp/mike.png"
					>
						<source
							src="https://practicum-content.s3.us-west-1.amazonaws.com/us-videos/2022_11_03_Videos%20of%20guidance%20team_Mike%20Lee.mp4"
							type="video/mp4"
						/>
						<source
							src="https://practicum-content.s3.us-west-1.amazonaws.com/usa-main/guidance/Tutors/2022_11_03_Videos%20of%20guidance%20team_Mike%20Lee.webm"
							type="video/webm"
						/>
					</video>
```

place the mp4 file first in your list instead of the webm. It will reduce much the networking usage.

[Jean-Yves Avenard [:jya]]

Pull request: https://github.com/WebKit/WebKit/pull/31396

[EWS]

Committed 281554@main (75467caf79bb): <https://commits.webkit.org/281554@main>

Reviewed commits have been landed. Closing PR #31396 and removing active labels.