PyQt+OpenCV 录制保存、播放视频

要使用 PyQt 结合 OpenCV 进行录制保存和播放视频，可以按照以下步骤进行：

1. 安装 PyQt 和 OpenCV 库：

pip install PyQt5
pip install opencv-python

2. 创建一个 PyQt 窗口，用于显示视频：

import sys
from PyQt5.QtWidgets import QApplication, QWidget, QLabel
from PyQt5.QtGui import QImage, QPixmap

class VideoPlayer(QWidget):
    def __init__(self):
        super().__init__()
        self.label = QLabel(self)
        self.setGeometry(100, 100, 640, 480)
        self.show()

3. 初始化 OpenCV 的摄像头，并将视频帧显示在 PyQt 窗口中：

import cv2

class VideoPlayer(QWidget):
    def __init__(self):
        super().__init__()
        self.label = QLabel(self)
        self.setGeometry(100, 100, 640, 480)
        self.show()

        self.cap = cv2.VideoCapture(0)
        self.timer = QTimer(self)
        self.timer.timeout.connect(self.update_frame)
        self.timer.start(50)

    def update_frame(self):
        ret, frame = self.cap.read()
        if ret:
            image = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
            h, w, ch = image.shape
            bytes_per_line = ch * w
            convert_to_QtFormat = QImage(image.data, w, h, bytes_per_line, QImage.Format_RGB888)
            p = convert_to_QtFormat.scaled(640, 480, Qt.KeepAspectRatio)
            self.label.setPixmap(QPixmap.fromImage(p))

4. 添加录制和保存视频的功能：

class VideoPlayer(QWidget):
    def __init__(self):
        super().__init__()
        self.label = QLabel(self)
        self.setGeometry(100, 100, 640, 480)
        self.show()

        self.cap = cv2.VideoCapture(0)
        self.timer = QTimer(self)
        self.timer.timeout.connect(self.update_frame)
        self.timer.start(50)

        self.recording = False
        self.video_writer = None

    def update_frame(self):
        ret, frame = self.cap.read()
        if ret:
            if self.recording:
                if self.video_writer is None:
                    fourcc = cv2.VideoWriter_fourcc(*'MJPG')
                    self.video_writer = cv2.VideoWriter('output.avi', fourcc, 20.0, (640, 480))
                self.video_writer.write(frame)
            image = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
            h, w, ch = image.shape
            bytes_per_line = ch * w
            convert_to_QtFormat = QImage(image.data, w, h, bytes_per_line, QImage.Format_RGB888)
            p = convert_to_QtFormat.scaled(640, 480, Qt.KeepAspectRatio)
            self.label.setPixmap(QPixmap.fromImage(p))

    def keyPressEvent(self, event):
        if event.key() == Qt.Key_Space:
            self.recording = not self.recording
            if not self.recording and self.video_writer is not None:
                self.video_writer.release()
                self.video_writer = None

5. 添加播放已保存视频的功能：

class VideoPlayer(QWidget):
    def __init__(self):
        super().__init__()
        self.label = QLabel(self)
        self.setGeometry(100, 100, 640, 480)
        self.show()

        self.cap = cv2.VideoCapture(0)
        self.timer = QTimer(self)
        self.timer.timeout.connect(self.update_frame)
        self.timer.start(50)

        self.recording = False
        self.video_writer = None

        self.playing = False
        self.video_capture = None

    def update_frame(self):
        ret, frame = self.cap.read()
        if ret:
            if self.recording:
                if self.video_writer is None:
                    fourcc = cv2.VideoWriter_fourcc(*'MJPG')
                    self.video_writer = cv2.VideoWriter('output.avi', fourcc, 20.0, (640, 480))
                self.video_writer.write(frame)
            image = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
            h, w, ch = image.shape
            bytes_per_line = ch * w
            convert_to_QtFormat = QImage(image.data, w, h, bytes_per_line, QImage.Format_RGB888)
            p = convert_to_QtFormat.scaled(640, 480, Qt.KeepAspectRatio)
            self.label.setPixmap(QPixmap.fromImage(p))

    def keyPressEvent(self, event):
        if event.key() == Qt.Key_Space:
            self.recording = not self.recording
            if not self.recording and self.video_writer is not None:
                self.video_writer.release()
                self.video_writer = None
        elif event.key() == Qt.Key_P:
            self.playing = not self.playing
            if self.playing:
                self.video_capture = cv2.VideoCapture('output.avi')
                self.timer.stop()
                self.timer.timeout.connect(self.update_saved_frame)
                self.timer.start(1000//30)
            else:
                self.timer.stop()
                self.timer.timeout.connect(self.update_frame)
                self.timer.start(50)

    def update_saved_frame(self):
        ret, frame = self.video_capture.read()
        if ret:
            image = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
            h, w, ch = image.shape
            bytes_per_line = ch * w
            convert_to_QtFormat = QImage(image.data, w, h, bytes_per_line, QImage.Format_RGB888)
            p = convert_to_QtFormat.scaled(640, 480, Qt.KeepAspectRatio)
            self.label.setPixmap(QPixmap.fromImage(p))

完整的代码如下：