Fix black video preview in burn-in / visual sync windows (#12205)#12235
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Windows that open a video right from their Loaded event (the burn-in and visual sync previews) issued mpv's "loadfile" before the rendering surface had lazily initialized the mpv core (mpv_initialize runs on the OpenGL control's first render pass). The command failed with MPV_ERROR_UNINITIALIZED and was never retried, leaving the preview black - along with all follow-up calls (pause, SetAudioTrack: "core not initialized"). The main window was unaffected only because its player idles until the user opens a file, long after the surface initialized. Track core initialization in LibMpvDynamicPlayer (set after mpv_initialize succeeds in all four init paths: OpenGL, Metal, software, native wid) and make LoadFile/LoadAudio wait (bounded, 5s) for it before sending commands. The wait is async on the UI thread, so the first render pass - which performs the initialization - is not blocked. Fixes #12205 Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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Problem
The video preview in the burn-in and visual sync windows stayed black until the window was resized/maximized (#12205). The main window's player was unaffected.
Root cause
Those windows open the video right from their
Loadedevent, but the mpv core is initialized lazily by the rendering surface — e.g. the OpenGL control callsInitializeWithOpenGL(→mpv_initialize) on its first render pass, which hasn't happened yet at that point. Theloadfilecommand therefore failed withMPV_ERROR_UNINITIALIZED(-3) and was never retried; all follow-up calls failed the same way (pause,SetAudioTrack: "core not initialized" in error-log.txt). Traced by logging theloadfileresult:The main window only works because its player idles until the user opens a file, long after the surface initialized.
Fix
In
LibMpvDynamicPlayer:_coreInitializedflag, set aftermpv_initializesucceeds in all four init paths (OpenGL, Metal, software rendering, native widInitialize()).LoadFile/LoadAudionow awaitWaitForCoreInitializedAsync()(25 ms polls, 5 s cap) before issuingloadfile. The wait is async on the UI thread, so the first render pass — which performs the initialization — is not blocked; the load fires right after init completes.If the surface never initializes (e.g. mpv missing), the bounded wait falls through and the command fails/logs exactly as before.
Testing
Fixes #12205
🤖 Generated with Claude Code