Can't extract last 2 frame

[timothyhalim]

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Description

Hi @cainmagi

When I try to extract last 2 frames of a video it return None

Here is the code used :

from PySide2.QtWidgets import QWidget, QLabel, QVBoxLayout, QApplication, QSlider
from PySide2.QtGui import QImage, QPixmap
from PySide2.QtCore import Qt

import mpegCoder
mpegCoder.setGlobal(dumpLevel=0)

class Player(QWidget):
    def __init__(self, parent=None):
        super(Player, self).__init__(parent)
        self._layout = QVBoxLayout(self)
        self.image = QLabel()
        self.slider = QSlider(Qt.Horizontal)
        self.slider.valueChanged.connect(self.extract_frame)
        self._layout.addWidget(self.image)
        self._layout.addWidget(self.slider)
        self.frames = []
        self.open_file()
        
    def close(self):
        self.decoder.clear()
        return super(Player, self).close()
        
    def open_file(self):
        self.decoder = mpegCoder.MpegDecoder()
        self.decoder.setParameter(nthread=4)
        opened = self.decoder.FFmpegSetup(r"30.mp4")
        
        if opened:
            duration = self.decoder.getParameter("duration")
            fps = self.decoder.getParameter("avgFrameRate")
            frameCount = duration*fps
            print("Video frame count is", frameCount)
            self.slider.setRange(0, frameCount-1) # -1 since start from 0
        
        self.extract_frame(0)
    
    def extract_frame(self, frame):
        print(frame)
        p = self.decoder.ExtractFrame(frame, 1)
        
        data = p[0].data
        height = p[0].shape[0]
        width = p[0].shape[1]
        channel = p[0].shape[2]
        pixmap = QPixmap.fromImage(QImage(data, width, height, channel*width, QImage.Format_RGB888))
        self.image.setPixmap(pixmap)
        
        
if __name__ == "__main__":
    import sys
    app = QApplication(sys.argv)
    p = Player()
    p.show()
    app.exec_()

You can change the frame by changing the slider

Here is the video used, 10sec/300frame video @30fps
the time code should be from 00:00 to 09:29
beeping every 1 sec/ 30 frame

30.mp4

Not really sure if this is a bug or if I'm doing something wrong

To Reproduce

1. Run the code
2. Change the slider
3. Error occur when extracting last 2 frame

Traceback

No response

Behaviors

1. The expected behaviors: able to extract every frame of the video
2. The actual behaviors: unable to extract last 2 frame of the video

Screenshots

No response

OS

Windows 10

Python version

3.9

numpy version

1.23.1

mpegCoder version

3.2.4

Additional context

No response

[cainmagi]

I am quite sure that this is a bug. When mpegCoder returns a None, it means the video has reached the last frame. In my expectation, it should read the 00:00:09:29 picture, and return a None after that. However, actually it reaches the None output after the 00:00:09:27 picture. It means that there are several frames that are not read. Currently, I have no idea why this bug happens, so I could not provide you with a solution instantly. Please give me a few weeks to tackle this problem. Recently I do not have plenty of time on this project but I think this issue may take me a long while to solve.

[timothyhalim]

ok thanks! @cainmagi