Bug 301485 – Video playback fails on PWA after reopening stuck on first frame

• Status: RESOLVED
• Resolution: DUPLICATE
• Component: New Bugs

Title
iOS: Videos in Home-Screen web apps (PWAs) show poster/first frame but don’t advance; play() resolves, frames don’t decode

Summary
When websites are added to the Home Screen and launched as standalone web apps, HTML5 video often gets stuck on the poster/first frame. HTMLMediaElement.play() resolves and media events fire (loadeddata → canplay → playing), but playback does not advance. This occurs across multiple, unrelated sites, including **YouTube** installed to the Home Screen and custom apps (e.g., Cloudinary MP4/HLS), indicating a system-wide iOS/WebKit issue in PWA context.


Steps to Reproduce
1) In Safari, open https://youtube.com.
2) Share → Add to Home Screen.
3) Launch the YouTube icon (standalone PWA).
4) Start any video (autoplay or manual play).
5) Observe: Events fire; but the poster/first frame remains and the picture does not update.

Expected
Video frames decode and advance; poster is replaced by video frames.

Actual
- play() promise resolves; loadeddata/canplay/playing fire.
- currentTime remains 0.
- No new frames decode: getVideoPlaybackQuality().totalVideoFrames stays constant (delta = 0).

Diagnostics (from Web Inspector on device)
- Event log shows playing without visual motion.
- Playback quality sampled at 500 ms intervals shows delta = 0 while paused = false.

Workarounds Tried
- Remove poster + tiny seek (currentTime += 0.01) after loadeddata → does not work.

Impact
Affects video playback across any Home-Screen web app, including major sites (YouTube) and enterprise PWAs; severe impact on media use-cases.

[Sam Sneddon [:gsnedders]]

*** This bug has been marked as a duplicate of bug 301484 ***