使用 QAudioOutput 和 QMediaPlayer (PyQt6) 的淡化效果

Posted 2023-03-25

【中文标题】使用 QAudioOutput 和 QMediaPlayer (PyQt6) 的淡化效果

【英文标题】：Fading effect with QAudioOutput and QMediaPlayer (PyQt6)

【发布时间】：2022-01-09 05:19:53

【问题描述】：

我正在开发一个音乐播放器应用程序，但我遇到了一个我不知道如何解决的问题。我希望音频在启动或取消暂停时以给定的间隔（例如 0.6 秒）淡入，并在暂停时以相同的间隔淡出。我尝试使用 QThread 来保持我的 ui 响应，同时使用 for 循环逐渐降低音量（迭代 10 次，每次降低音量并睡眠一定时间，0.6 / 10 秒）。但它不起作用，按钮仍然不可点击，只有在淡入或淡出后才会更新。如果有人设法解决了这样的问题，请提供帮助，将不胜感激！下面是在pyqt中播放音频的简单代码：

import sys

from PyQt6 import QtWidgets
from PyQt6.QtCore import QUrl
from PyQt6.QtMultimedia import QMediaPlayer, QAudioOutput
from PyQt6.QtWidgets import QWidget, QVBoxLayout, QPushButton, QStyle


class MainWindowUi(QtWidgets.QMainWindow):
    def __init__(self):
        super().__init__()

        self._setup_ui()

        self.setWindowTitle('sound fading')
        self.setGeometry(100, 100, 100, 100)

    def _setup_ui(self):
        self.central_widget = QWidget(self)
        self.central_widget_layout = QVBoxLayout(self.central_widget)
        self.setCentralWidget(self.central_widget)

        self.player = AudioPlayer()
        self.user_action = -1  # 0 - stopped, 1 - playing, 2 - paused
        self.play_button = QPushButton()
        self.play_button.clicked.connect(self.play_pause_button_clicked)

        self.play_icon = self.style().standardIcon(QStyle.StandardPixmap.SP_MediaPlay)
        self.pause_icon = self.style().standardIcon(QStyle.StandardPixmap.SP_MediaPause)
        self.play_button.setIcon(self.play_icon)

        self.central_widget_layout.addWidget(self.play_button)

    def play(self):
        print("Play")
        self.play_button.setIcon(self.pause_icon)
        self.user_action = 1
        self.player.setSource(QUrl("Some audio file path goes here."))
        self.player.play()

    def pause(self):
        print("Pause")
        self.play_button.setIcon(self.play_icon)
        self.user_action = 2
        self.player.pause()

    def unpause(self):
        print("Unpause")
        self.play_button.setIcon(self.pause_icon)
        self.user_action = 1
        self.player.play()

    def play_pause_button_clicked(self):
        if self.user_action <= 0:
            self.play()
        elif self.user_action == 1:
            self.pause()
        elif self.user_action == 2:
            self.unpause()


class AudioPlayer(QMediaPlayer):
    def __init__(self, parent=None):
        super().__init__(parent)
        self.audio_output = QAudioOutput()
        self.setAudioOutput(self.audio_output)
        self.audioOutput().setVolume(0.3)
        self.current_volume = self.audio_output.volume()

    def play(self):
        super().play()

    def pause(self):
        super().pause()


if __name__ == '__main__':
    app = QtWidgets.QApplication(sys.argv)
    mainWindow = MainWindowUi()
    mainWindow.show()

    sys.exit(app.exec())

【问题讨论】：

听起来您正在寻找类似QVariantAnimation 的东西（链接是PySide2——由于某种原因找不到相关的PyQt6 文档。）

是的！非常感谢，我在音频输出音量上使用了 QPropertyAnimation，效果很好！

@N1teShad0w 我建议您使用minimal reproducible example 发布您自己的答案，以展示您是如何解决问题的，因为它可能对其他人也有用。

【参考方案1】：

所以我让它与 QPropertyAnimation 一起工作！仍在处理关键值和缓动曲线，但确实更接近我想要的结果。

import sys

from PyQt6 import QtWidgets
from PyQt6.QtCore import QUrl, QPropertyAnimation, QEasingCurve
from PyQt6.QtMultimedia import QMediaPlayer, QAudioOutput
from PyQt6.QtWidgets import QWidget, QVBoxLayout, QPushButton, QStyle

from audio_player import AudioPlayer


class MainWindowUi(QtWidgets.QMainWindow):
    def __init__(self):
        super().__init__()

        self._setup_ui()

        self.setWindowTitle('sound fading')
        self.setGeometry(100, 100, 100, 100)

    def _setup_ui(self):
        self.central_widget = QWidget(self)
        self.central_widget_layout = QVBoxLayout(self.central_widget)
        self.setCentralWidget(self.central_widget)

        self.player = AudioPlayer()
        self.user_action = -1  # 0 - stopped, 1 - playing, 2 - paused
        self.play_button = QPushButton()
        self.play_button.clicked.connect(self.play_pause_button_clicked)

        self.play_icon = self.style().standardIcon(QStyle.StandardPixmap.SP_MediaPlay)
        self.pause_icon = self.style().standardIcon(QStyle.StandardPixmap.SP_MediaPause)
        self.play_button.setIcon(self.play_icon)

        self.central_widget_layout.addWidget(self.play_button)

    def play(self):
        print("Play")
        self.play_button.setIcon(self.pause_icon)
        self.user_action = 1
        self.player.setSource(QUrl("some audio file path"))
        self.player.play()

    def pause(self):
        print("Pause")
        self.play_button.setIcon(self.play_icon)
        self.user_action = 2
        self.player.pause()

    def unpause(self):
        print("Unpause")
        self.play_button.setIcon(self.pause_icon)
        self.user_action = 1
        self.player.play()

    def play_pause_button_clicked(self):
        if self.user_action <= 0:
            self.play()
        elif self.user_action == 1:
            self.pause()
        elif self.user_action == 2:
            self.unpause()


class AudioPlayer(QMediaPlayer):
    def __init__(self, parent=None):
        super().__init__(parent)
        self.audio_output = QAudioOutput()
        self.audio_output.volumeChanged.connect(lambda: print(self.audio_output.volume()))
        self.setAudioOutput(self.audio_output)
        self.audioOutput().setVolume(.5)
        self.current_volume = self.audio_output.volume()

        self.fade_in_anim = QPropertyAnimation(self.audio_output, b"volume")
        self.fade_in_anim.setDuration(1400)
        self.fade_in_anim.setStartValue(0.01)
        self.fade_in_anim.setEndValue(self.current_volume)
        self.fade_in_anim.setEasingCurve(QEasingCurve.Type.Linear)
        self.fade_in_anim.setKeyValueAt(0.01, 0.01)

        self.fade_out_anim = QPropertyAnimation(self.audio_output, b"volume")
        self.fade_out_anim.setDuration(600)
        self.fade_out_anim.setStartValue(self.current_volume)
        self.fade_out_anim.setEndValue(0)
        self.fade_out_anim.setEasingCurve(QEasingCurve.Type.Linear)
        self.fade_out_anim.setKeyValueAt(0.01, self.current_volume)
        self.fade_out_anim.finished.connect(super().pause)

    def play(self):
        self.audio_output.setVolume(0.01)
        self.fade_in_anim.setEndValue(self.current_volume)
        super().play()
        self.fade_in_anim.start()

    def pause(self):
        self.current_volume = self.audio_output.volume()
        self.fade_out_anim.setStartValue(self.current_volume)
        self.fade_out_anim.start()


if __name__ == '__main__':
    app = QtWidgets.QApplication(sys.argv)
    mainWindow = MainWindowUi()
    mainWindow.show()

    sys.exit(app.exec())