fix(mpv): avoid render stalls from video timing offset (#6)

mpvqt renders without disabling MPV_RENDER_PARAM_BLOCK_FOR_TARGET_TIME, so each new video frame blocks the Qt Quick render thread for up to video-timing-offset (50 ms). Animations over a playing video (playlist slide-in) stuttered; paused video was smooth. Set video-timing-offset=0.

Measured offscreen while toggling the playlist during playback: worst frame 35–39 ms before, 17–21 ms after.

Reviewed-on: #6
Co-authored-by: Tri Vo Khac <git@trivk.dev>

src/mpv/mpvitem.cpp

@@ -33,6 +33,10 @@ MpvItem::MpvItem(QQuickItem *parent)
     // Leave the player on the last frame at end of file instead of unloading it.
     setPropertyAsync(QStringLiteral("keep-open"), QStringLiteral("yes"));
     setPropertyAsync(QStringLiteral("hwdec"), QStringLiteral("auto-safe"));
+    // mpvqt renders with the default blocking timing, so each new video frame stalls
+    // the Qt Quick render thread for up to this offset (50 ms) and animations drawn
+    // over a playing video stutter. Hand frames over at their display time instead.
+    setPropertyAsync(QStringLiteral("video-timing-offset"), 0);
     // Also pick up "movie.en.srt" style files next to "movie.mkv".
     setPropertyAsync(QStringLiteral("sub-auto"), QStringLiteral("fuzzy"));