问题
I am creating a program to play videos and then process them. I am able to play the videos with QMediaPlayer. How do I access specific frames as images or something similar. My end goal would be to format the video into a 4-d tensor of size [Num of frames, width_of_video, height_of_video, channels].
Here is the code that loads my video.:
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()
回答1:
Here is a working example that I converted to Python from the C++ version available in this question: How to save a frame using QMediaPlayer?
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_())
来源：https://stackoverflow.com/questions/52359924/pyqt5-access-frames-with-qmediaplayer