如何在 Python VLC MediaPlayer 中使用 QFile

如何解决如何在 Python VLC MediaPlayer 中使用 QFile

我可以使用以下代码从文件中简单地播放 wav 文件：

media = vlc.MediaPlayer('c.wav')
media.audio_set_volume(50)
media.play()

我如何对 qrc 资源文件做同样的事情？我试过这段代码，但似乎不起作用：

mediafile = QFile(':/sounds/c.wav')
media = vlc.Instance().media_player_new()
media.set_media(mediafile)
media.audio_set_volume(50)
media.play()

解决方法

您需要为此使用 vlc.media_new_callbacks，以便您可以包装 QFile 并使用其方法。下面是一个演示脚本，展示了如何实现：

import sys,vlc
from PyQt5.QtCore import QFile,QCoreApplication

@vlc.CallbackDecorators.MediaOpenCb
def open_cb(opaque,data,size):
    data.contents.value = opaque
    size.value = sys.maxsize
    return 0

@vlc.CallbackDecorators.MediaReadCb
def read_cb(opaque,buffer,length):
    data = qfile.read(length)
    for index,char in enumerate(data):
        buffer[index] = char
    return len(data)

@vlc.CallbackDecorators.MediaSeekCb
def seek_cb(opaque,offset):
    qfile.seek(offset)
    return 0

@vlc.CallbackDecorators.MediaCloseCb
def close_cb(opaque):
    qfile.close()

if __name__ == '__main__':

    import time,signal
    signal.signal(signal.SIGINT,signal.SIG_DFL)

    print('Press Ctrl+C to Quit')

    player = vlc.Instance().media_player_new()

    qfile = QFile(sys.argv[1])
    qfile.open(QFile.ReadOnly)

    player.set_media(vlc.Instance().media_new_callbacks(
        open_cb,read_cb,seek_cb,close_cb,None))

    player.play()

    app = QCoreApplication(sys.argv)
    app.exec_()

---

更新：

在更典型的 PyQt 应用程序中让它正常工作有点棘手，因为回调必须是静态函数。这是一个扩展示例，展示了如何完成：

import sys,ctypes,vlc
from PyQt5 import QtCore,QtWidgets

class VLCPlayer(QtCore.QObject):
    def __init__(self,parent=None):
        super().__init__()
        self._player = vlc.Instance().media_player_new()

    @staticmethod
    @vlc.CallbackDecorators.MediaOpenCb
    def _open_cb(voidptr,size):
        data.contents.value = voidptr
        size.value = sys.maxsize
        return 0

    @staticmethod
    @vlc.CallbackDecorators.MediaReadCb
    def _read_cb(voidptr,length):
        stream = ctypes.cast(
            voidptr,ctypes.POINTER(ctypes.py_object)).contents.value
        data = stream.read(length)
        for index,char in enumerate(data):
            buffer[index] = char
        return len(data)

    @staticmethod
    @vlc.CallbackDecorators.MediaSeekCb
    def _seek_cb(voidptr,offset):
        stream = ctypes.cast(
            voidptr,ctypes.POINTER(ctypes.py_object)).contents.value
        stream.seek(offset)
        return 0

    @staticmethod
    @vlc.CallbackDecorators.MediaCloseCb
    def _close_cb(voidptr):
        stream = ctypes.cast(
            voidptr,ctypes.POINTER(ctypes.py_object)).contents.value
        stream.close()

    def play(self):
        self._player.play()

    def stop(self):
        self._player.stop()

    def load(self,path):
        file = QtCore.QFile(path)
        file.open(QtCore.QIODevice.ReadOnly)
        voidptr = ctypes.cast(ctypes.pointer(
            ctypes.py_object(file)),ctypes.c_void_p)
        self._player.set_media(vlc.Instance().media_new_callbacks(
            self._open_cb,self._read_cb,self._seek_cb,self._close_cb,voidptr))


class Window(QtWidgets.QWidget):
    def __init__(self):
        super().__init__()
        self.buttonPlay = QtWidgets.QPushButton('Play')
        self.buttonPlay.clicked.connect(self.handlePlay)
        self.buttonStop = QtWidgets.QPushButton('Stop')
        self.buttonStop.clicked.connect(self.handleStop)
        self.buttonOpen = QtWidgets.QPushButton('Open')
        self.buttonOpen.clicked.connect(self.handleOpen)
        layout = QtWidgets.QHBoxLayout(self)
        layout.addWidget(self.buttonOpen)
        layout.addWidget(self.buttonPlay)
        layout.addWidget(self.buttonStop)
        self.player = VLCPlayer(self)

    def handlePlay(self):
        self.player.play()

    def handleStop(self):
        self.player.stop()

    def handleOpen(self):
        path,ok = QtWidgets.QFileDialog.getOpenFileName(
            self,filter='Audio Files (*.wav)')
        if ok:
            self.player.load(path)

if __name__ == '__main__':

    app = QtWidgets.QApplication(sys.argv)
    window = Window()
    window.setWindowTitle('VLC Player')
    window.setGeometry(600,100,200,80)
    window.show()
    sys.exit(app.exec_())