Hi WebKit team, I’m curious about the original rationale behind the restriction that prevents concurrent playback of multiple <video> elements. Was it primarily introduced to save battery life?
In practice, this behavior appears to have unintended side effects. There’s a reproducible issue where playback can be started with the video muted and then immediately unmuted, effectively bypassing the restriction. However, this often results in videos being randomly paused later—sometimes very frequently—leading to a “play/pause ping-pong” between Safari/WebKit and JavaScript restarting playback. This erratic behavior may actually *increase* battery consumption, despite appearing to work smoothly from the user’s perspective. Even if this workaround is eventually blocked, developers who rely on concurrent playback (e.g., outside of WebRTC contexts) will turn to more complex solutions, such as decoding video and audio using WebCodecs or/and WebAssembly, and rendering via <canvas> and AudioContext. While technically feasible, these approaches are likely to be significantly less power-efficient than simply allowing multiple <video> elements to play concurrently. Another similarly inefficient workaround would be to synthesize a MediaStream using the VideoTrackGenerator API and AudioContext.createMediaStreamDestination(). Lastly, another issue is that creating a MediaElementSource from a <video> element and routing its audio through a shared AudioContext also does not disable the playback restriction—whereas it *is* disabled when the <video> element itself is muted. This feels inconsistent and may point to a separate bug. Could you please clarify the motivation behind this restriction, and whether there are any plans to revisit or improve its behavior? Thank you!
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