PyQt5 Access Frames with QmediaPlayer

Question

>我正在创建一个程序来播放视频，然后处理它们。我能够用QMediaPlayer播放视频。如何以图像或类似内容的形式访问特定帧。我的最终目标是将视频格式化为大小为 [帧数、width_of_video、height_of_video、通道数] 的 4-D 张量。

这是加载我的视频的代码。

self.clear_layout(self.vlayout)
videoItem = QVideoWidget()
self.mediaPlayer = QMediaPlayer(None, QMediaPlayer.VideoSurface)
self.mediaPlayer.durationChanged.connect(self.update_duration)     
self.mediaPlayer.positionChanged.connect(self.update_slider_position)
self.vlayout.addWidget(videoItem)
self.mediaPlayer.setVideoOutput(videoItem)
local = QUrl.fromLocalFile(self.video_paths)
media = QMediaContent(local)
self.mediaPlayer.setMedia(media)
self.play_video()

Answer 1

这是我从此问题中可用的C++版本转换为 Python 的一个工作示例： 如何使用QMediaPlayer保存帧？

import sys
import uuid
import PyQt5
from PyQt5 import QtCore, QtWidgets
from PyQt5.QtCore import Qt, QObject, QUrl, QRect, pyqtSignal, QPoint
from PyQt5.QtGui import QPainter, QImage
from PyQt5.QtWidgets import QWidget, QApplication, QMainWindow, QGridLayout, QToolBar, QAction
from PyQt5.QtMultimedia import QMediaPlayer, QMediaContent, QAbstractVideoBuffer, 
QVideoFrame, QVideoSurfaceFormat, QAbstractVideoSurface
from PyQt5.QtMultimediaWidgets import QVideoWidget

class VideoFrameGrabber(QAbstractVideoSurface):
frameAvailable = pyqtSignal(QImage)
def __init__(self, widget: QWidget, parent: QObject):
super().__init__(parent)
self.widget = widget
def supportedPixelFormats(self, handleType):
return [QVideoFrame.Format_ARGB32, QVideoFrame.Format_ARGB32_Premultiplied,
QVideoFrame.Format_RGB32, QVideoFrame.Format_RGB24, QVideoFrame.Format_RGB565,
QVideoFrame.Format_RGB555, QVideoFrame.Format_ARGB8565_Premultiplied,
QVideoFrame.Format_BGRA32, QVideoFrame.Format_BGRA32_Premultiplied, QVideoFrame.Format_BGR32,
QVideoFrame.Format_BGR24, QVideoFrame.Format_BGR565, QVideoFrame.Format_BGR555,
QVideoFrame.Format_BGRA5658_Premultiplied, QVideoFrame.Format_AYUV444,
QVideoFrame.Format_AYUV444_Premultiplied, QVideoFrame.Format_YUV444,
QVideoFrame.Format_YUV420P, QVideoFrame.Format_YV12, QVideoFrame.Format_UYVY,
QVideoFrame.Format_YUYV, QVideoFrame.Format_NV12, QVideoFrame.Format_NV21,
QVideoFrame.Format_IMC1, QVideoFrame.Format_IMC2, QVideoFrame.Format_IMC3,
QVideoFrame.Format_IMC4, QVideoFrame.Format_Y8, QVideoFrame.Format_Y16,
QVideoFrame.Format_Jpeg, QVideoFrame.Format_CameraRaw, QVideoFrame.Format_AdobeDng]
def isFormatSupported(self, format):
imageFormat = QVideoFrame.imageFormatFromPixelFormat(format.pixelFormat())
size = format.frameSize()
return imageFormat != QImage.Format_Invalid and not size.isEmpty() and 
format.handleType() == QAbstractVideoBuffer.NoHandle
def start(self, format: QVideoSurfaceFormat):
imageFormat = QVideoFrame.imageFormatFromPixelFormat(format.pixelFormat())
size = format.frameSize()
if imageFormat != QImage.Format_Invalid and not size.isEmpty():
self.imageFormat = imageFormat
self.imageSize = size
self.sourceRect = format.viewport()
super().start(format)
self.widget.updateGeometry()
self.updateVideoRect()
return True
else:
return False
def stop(self):
self.currentFrame = QVideoFrame()
self.targetRect = QRect()
super().stop()
self.widget.update()
def present(self, frame):
if frame.isValid():
cloneFrame = QVideoFrame(frame)
cloneFrame.map(QAbstractVideoBuffer.ReadOnly)
image = QImage(cloneFrame.bits(), cloneFrame.width(), cloneFrame.height(),
QVideoFrame.imageFormatFromPixelFormat(cloneFrame.pixelFormat()))
self.frameAvailable.emit(image)  # this is very important
cloneFrame.unmap()
if self.surfaceFormat().pixelFormat() != frame.pixelFormat() or 
self.surfaceFormat().frameSize() != frame.size():
self.setError(QAbstractVideoSurface.IncorrectFormatError)
self.stop()
return False
else:
self.currentFrame = frame
self.widget.repaint(self.targetRect)
return True
def updateVideoRect(self):
size = self.surfaceFormat().sizeHint()
size.scale(self.widget.size().boundedTo(size), Qt.KeepAspectRatio)
self.targetRect = QRect(QPoint(0, 0), size)
self.targetRect.moveCenter(self.widget.rect().center())
def paint(self, painter):
if self.currentFrame.map(QAbstractVideoBuffer.ReadOnly):
oldTransform = self.painter.transform()
if self.surfaceFormat().scanLineDirection() == QVideoSurfaceFormat.BottomToTop:
self.painter.scale(1, -1)
self.painter.translate(0, -self.widget.height())
image = QImage(self.currentFrame.bits(), self.currentFrame.width(), self.currentFrame.height(),
self.currentFrame.bytesPerLine(), self.imageFormat)
self.painter.drawImage(self.targetRect, image, self.sourceRect)
self.painter.setTransform(oldTransform)
self.currentFrame.unmap()

class App(QApplication):
def __init__(self, sys_argv):
super().__init__(sys_argv)
# Show main window
self.view = QMainWindow()
self.centralWidget = QWidget(self.view)
self.gridLayout = QGridLayout(self.centralWidget)
self.gridLayout.setContentsMargins(0, 0, 0, 0)
self.gridLayout.setSpacing(0)
self.video_item = QVideoWidget()
self.gridLayout.addWidget(self.video_item)
self.view.setCentralWidget(self.centralWidget)
self.mediaPlayer = QMediaPlayer(None, QMediaPlayer.VideoSurface)
self.grabber = VideoFrameGrabber(self.video_item, self)
self.mediaPlayer.setVideoOutput(self.grabber)
self.grabber.frameAvailable.connect(self.process_frame)
self.mediaPlayer.durationChanged.connect(self.update_duration)
self.mediaPlayer.positionChanged.connect(self.update_slider_position)
local = QUrl.fromLocalFile('c:/temp/lorem.mp4')
media = QMediaContent(local)
self.mediaPlayer.setMedia(media)
self.mediaPlayer.play()
self.view.show()
def process_frame(self, image):
# Save image here
image.save('c:/temp/{}.jpg'.format(str(uuid.uuid4())))
def update_duration(self):
pass
def update_slider_position(self):
pass

if __name__ == '__main__':
def except_hook(cls, exception, traceback):
sys.__excepthook__(cls, exception, traceback)

if hasattr(QtCore.Qt, 'AA_EnableHighDpiScaling'):
PyQt5.QtWidgets.QApplication.setAttribute(QtCore.Qt.AA_EnableHighDpiScaling, True)
if hasattr(QtCore.Qt, 'AA_UseHighDpiPixmaps'):
PyQt5.QtWidgets.QApplication.setAttribute(QtCore.Qt.AA_UseHighDpiPixmaps, True)
app = App(sys.argv)
app.setAttribute(QtCore.Qt.AA_EnableHighDpiScaling)
sys.excepthook = except_hook
sys.exit(app.exec_())