The seek slider snapped visually backward after a click for the first
~tens to hundreds of ms — long enough to be obvious. Race trace:
user clicks slider at target T
→ _ClickSeekSlider.mousePressEvent fires
→ setValue(T) lands the visual at the click position
→ clicked_position emits → _seek dispatches mpv.seek(T) async
→ mpv processes the seek on its own thread
meanwhile the 100ms _poll timer keeps firing
→ reads mpv.time_pos (still the OLD position, mpv hasn't caught up)
→ calls self._seek_slider.setValue(pos_ms)
→ slider visually snaps backward to the pre-seek position
→ mpv finishes seeking, next poll tick writes the new position
→ slider jumps forward to settle near T
The isSliderDown() guard at the existing setValue site (around line
425) only suppresses writebacks during a *drag* — fast clicks never
trigger isSliderDown, so the guard didn't help here.
Fix: pin the slider to the user's target throughout a 500ms post-seek
window. Mirror the existing _eof_ignore_until pattern (stale-eof
suppression in play_file → _on_eof_reached) — it's the same shape:
"after this dispatch, ignore poll-driven writebacks for N ms because
mpv hasn't caught up yet."
- _seek now records _seek_target_ms and arms _seek_pending_until
- _poll forces _seek_slider.setValue(_seek_target_ms) on every tick
inside the window, instead of mpv's lagging time_pos
- After the window expires, normal mpv-driven writes resume
Pin window is 500ms (vs the eof window's 250ms) because network and
streaming seeks take noticeably longer than local-cache seeks. Inside
the window the slider is forced to the target every tick, so mpv lag
is invisible no matter how long it takes within the window.
First attempt used a smaller 250ms window with a "close enough"
early-release condition (release suppression once mpv reports a
position within 250ms of the target). That still showed minor
track-back because the "close enough" threshold permitted writing
back a position slightly less than the target, producing a small
visible jump. The pin-to-target approach is robust against any
mpv interim position.
The time_label keeps updating to mpv's actual position throughout —
only the slider value is pinned, so the user can still see the
seek progressing in the time text.
Verified manually: clicks at start / middle / end of a video slider
all hold position cleanly. Drag still works (the isSliderDown path
is untouched). Normal playback advances smoothly (the pin window
only affects the post-seek window, not steady-state playback).
pax
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