WeAreSyncing/player_widget.py

import locale
import os
import time

# The dev machine has a locally-built libmpv in /usr/local/lib that isn't
# registered with ldconfig. LD_LIBRARY_PATH must be set in the environment
# *before this process starts* (dlopen reads it at exec time) -- see run
# scripts / README for the wrapper that does this.

import mpv
from PyQt6.QtWidgets import QWidget
from PyQt6.QtCore import Qt, pyqtSignal


class PlayerWidget(QWidget):
    """Embeds an mpv render surface in a Qt widget.

    Frame-accurate seeking relies on mpv's hr-seek (decode-and-discard to the
    exact target instead of snapping to the nearest keyframe), which is why
    this exists instead of a QMediaPlayer/HTML5-video-style backend.
    """

    fileDropped = pyqtSignal(str)
    rightClicked = pyqtSignal()

    def __init__(self, parent=None):
        super().__init__(parent)
        self.setAttribute(Qt.WidgetAttribute.WA_DontCreateNativeAncestors)
        self.setAttribute(Qt.WidgetAttribute.WA_NativeWindow)
        self.setAcceptDrops(True)
        self.setContextMenuPolicy(Qt.ContextMenuPolicy.NoContextMenu)

        # QApplication resets LC_NUMERIC to the system locale on construction,
        # which undoes python-mpv's own import-time fix and makes libmpv abort
        # with "Non-C locale detected" -- reset it again right before libmpv
        # actually gets instantiated.
        locale.setlocale(locale.LC_NUMERIC, "C")

        self.mpv = mpv.MPV(
            wid=str(int(self.winId())),
            vo="gpu",
            hr_seek="yes",
            hr_seek_framedrop="no",
            keep_open="yes",
            pause=True,
        )
        self._fps = None

        # mpv owns its own native child window for rendering (that's how
        # wid-embedding works), which receives raw X11 input directly --
        # confirmed by testing that a real mouse click never reaches this
        # QWidget's mousePressEvent at all, even though it looked fine when
        # the handler was called directly in a unit-style test. Mouse
        # buttons have to be bound through mpv's own input system instead.
        self.mpv.on_key_press("MBTN_RIGHT")(lambda: self.rightClicked.emit())

    def load(self, path: str):
        # NOTE: we start the MPV instance with pause=True, so `core-idle`
        # never flips to False and mpv.wait_until_playing() would block
        # forever. Wait for `duration` to populate instead, which happens
        # once the file is loaded regardless of pause state.
        self.mpv.play(path)
        self.mpv.wait_for_property("duration", timeout=10)
        self.mpv.pause = True
        self._fps = self.mpv.container_fps or self.mpv.estimated_vf_fps

    def play(self):
        self.mpv.pause = False

    def pause(self):
        self.mpv.pause = True

    def seek(self, seconds: float):
        before = self.mpv.estimated_frame_number
        self.mpv.seek(seconds, reference="absolute", precision="exact")
        self._wait_for_frame_change(before)

    def step_frame(self, n: int = 1):
        # frame-step is async: the command returns immediately and the
        # actual decode/seek happens on mpv's internal thread. Without
        # waiting for confirmation, rapid-fire commands get coalesced or
        # dropped (observed: some steps silently no-op, others jump 2-3
        # frames at once when driven by a fixed sleep guess).
        #
        # `playback-restart` -- the event mpv's own docs point to for this --
        # turned out to never fire with our vo=gpu Qt-embedded surface (nor
        # with vo=null in an isolated test), even though the underlying
        # decode/seek completes correctly and quickly. So instead we poll
        # `estimated_frame_number` directly until it changes, which was
        # confirmed reliable in isolated testing (see scripts/mpv_bare_test.py).
        cmd = "frame-step" if n >= 0 else "frame-back-step"
        for _ in range(abs(n)):
            before = self.mpv.estimated_frame_number
            self.mpv.command(cmd)
            self._wait_for_frame_change(before)

    def _wait_for_frame_change(self, before, timeout=1.0):
        deadline = time.monotonic() + timeout
        while time.monotonic() < deadline:
            current = self.mpv.estimated_frame_number
            if current is not None and current != before:
                return
            time.sleep(0.005)

    def get_position(self) -> float:
        return self.mpv.time_pos or 0.0

    def get_estimated_frame(self) -> int:
        return self.mpv.estimated_frame_number or 0

    def fps(self) -> float:
        return self._fps or 0.0

    def screenshot(self, path: str):
        # `estimated_frame_number` updates as soon as the demuxer/decoder
        # reports the new position, slightly ahead of the vo=gpu surface
        # actually finishing its render -- give it a couple frames' worth
        # of slack so the screenshot doesn't grab the previous frame.
        time.sleep(0.05)
        self.mpv.screenshot_to_file(path, includes="video")

    def shutdown(self):
        self.mpv.terminate()

    def dragEnterEvent(self, event):
        if event.mimeData().hasUrls() and any(u.isLocalFile() for u in event.mimeData().urls()):
            event.acceptProposedAction()

    def dropEvent(self, event):
        for url in event.mimeData().urls():
            if url.isLocalFile():
                self.fileDropped.emit(url.toLocalFile())
                event.acceptProposedAction()
                return