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• How to control webcam's exposure time (using V4L2) based on the certain pixel's value ?

  16 avril 2022, par Garid

  I'd like to control the exposure time such that certain average value of certain window (e.g. 10x10+230+70) always fall between 100 to 220.

  


  /p.s. Camera is monochrome/

  


  Something like following :

  


  loop
    if average value > 220:
        v4l2: lower the exposure
    else if average value > 100:
        v4l2: higher the exposure
    else if 100 < average value < 220:
        break the loop


  


  I can do this with Python with OpenCV. I'm looking for another solutions

  


  Is there any solutions with ffmpeg, or imagemagick ?

  


• Anomalie #4836 : Graphiques et interface arabe

  28 juin 2021, par George Kandalaft

  Ou plutot est-il possible d’avoir les mois en arabe dans l’ineterface arabe ?

• ffmpeg real-time buffer too full or near too full frame dropped, I even tried increasing rtbufsize. What could be going wrong ?

  21 mai 2024, par Ali Azlan

  We have a software where we capture the stream from the camera connected to the laptop or device using ffmpeg python,

  


                   ffmpeg
                .input(video, s='640x480', **self.args) //tried with rtbufsize=1000M (enough I suupose/ also sometimes the error does not occur even on default rtbufsize which is around 3MB)
                .output('pipe:', format='rawvideo', pix_fmt='rgb24')
                .overwrite_output()
                .run_async(pipe_stdout=True) 


  


  majority of the times when I start the software like the software is still initiating we receive the following error, I have also received this error when the software has initiated fully and completely and it is running from a long time like after 12hrs or more.

  


  


  Error : [dshow @ 000002248916e240] real-time buffer [Integrated
Camera] [video input] too full or near too full (80% of size : 3041280
[rtbufsize parameter]) ! frame dropped !
Last message repeated 1 times [dshow @ 000002248916e240] real-time buffer [Integrated Camera] [video input] too full or near too full
(101% of size : 3041280 [rtbufsize parameter]) ! frame dropped !

  


  


  What are the things we possibly might be doing wrong ?

  


  Edit 1 :

  


  below is the code to consume the frame captured in the video using ffmpeg

  


      def frame_reader(self):
    while True:
        in_bytes = self.process.stdout.read(self.width * self.height * 3)
        if not in_bytes:
            break
        try:
            in_frame = (
                np
                    .frombuffer(in_bytes, np.uint8)
                    .reshape([self.height, self.width, 3])
            )
            frame = cv2.resize(in_frame, (640, 480))
            frame = cv2.cvtColor(frame, cv2.COLOR_RGB2BGR)
        except Exception as e:
            logger.error(e, exc_info=True)
            in_frame = (
                np
                    .frombuffer(in_bytes, np.uint8)
            )

        if not self.q.empty():
            try:
                self.q.get_nowait()
            except queue.Empty:
                pass
        self.q.put(frame)