Safari 15.1 H264 FullHD video encode/decode fails

• Component: WebRTC
• Status: RESOLVED FIXED

[milen]

Tested on:
macOS: 12.0.1, Mac mini (2018)
Safari: Version 15.1 (17612.2.9.1.20)
WebCam: Logitech C910

Steps to reproduce the issue:
1) Go to https://webrtc.github.io/samples/src/content/peerconnection/constraints/
2) Change the resolution settings to FullHD (1920x1080).
```
    "video": {
        "width": {
            "min": "1851",
            "max": "4096"
        },
        "height": {
            "min": "1053",
            "max": "2160"
        }
    }

```
3) Click the button 'Get Media'
4) Click the button 'Connect'

The result is: Output video is black

-----

Some observations:

1) There is a Safari settings: Developer > Experimental Features > Webrtc H264 LowLatency Encoder. This is enabled by default. If it is turned OFF then the above scenario (H264 with FullHD) works fine.

2) If the resolution is up to HD (1280x720) then the above scenario works fine. Anything above 1280x720 causes black output.

3) If the codec is VP8 or VP9 then there is no problem with FullHD video.

4) The same issue happens also if the video is encoded on desktop Safari 15.1 and decoded on mobile Safari 15.1 (iOS).

5) The issue is not present if the video is encoded on desktop Safari 15.1 and decoded on desktop Chrome 95. H264 with FullHD works fine is this case.

[milen]

It is kinda hard to set exact FullHD settings with the sample above.
Anything above 1280x720 and below 1920x1080 seems to reproduce it.

In my case 
{
    "audio": true,
    "video": {
        "width": {
            "min": "300",
            "max": "1887"
        },
        "height": {
            "min": "200",
            "max": "1015"
        }
    }
}

results in: "Video dimensions: 1887x1015px"

[youenn fablet]

<rdar://80345048>

[youenn fablet]

Created attachment 444500 [details]
Patch

[EWS]

Committed r285928 (244337@main): <https://commits.webkit.org/244337@main>

All reviewed patches have been landed. Closing bug and clearing flags on attachment 444500 [details].

[youenn fablet]

*** Bug 236870 has been marked as a duplicate of this bug. ***