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• OpenCV Threading Capture Loses Connection to IP Camera

  27 janvier 2021, par David López Díaz

  I have a surveillance program that opens 16 threads to check on to 16 different cameras with live video, but when after some time (20/30 seconds) cameras starts to lose frames and I need to reconnect them.

  


  The thing is that if I only open 10 streams at once it might lose a frame from time to time, but if I open 16 streams it begins to fail every 20 seconds or so.

  


  I've checked system params, and CPU doesnt go more than 50% and RAM is on 4GB, so this doesnt look like the problem.
Also I've checked the network and it's fine, no delay and no packet loss.

  


  Sometime I get error while decoding MB 8 7, bytestream -5

  


  This is the thread I use to get the streams.

  


      """
    Class that continuously gets frames from a VideoCapture object
    with a dedicated thread.
    """
    def __init__(self, idcam,ipcamara, user, passwd,resolucionh,resolucionw):
        self.id = idcam
        self.ip = ipcamara
        self.user = user
        self.passwd = passwd
        self.Q =[]
        self.scale_percent = 50
        self.i = 0

    def start(self):
        self.conectar()
        Thread(target=self.get, args=()).start()
        return self

    def get(self):

        while True:
            if(self.stream.isOpened() and self.online):
                (status, preFrame) = self.stream.read()
                if(status):
                    self.frame = (preFrame)
                else:
                    self.stream.release()
                    self.online = False
            else:
                graba_log('Camara '+str(self.id),'Desconexion')
                self.conectar()
                time.sleep(1)

    def conectar(self):
        print('Iniciando conexion con camara '+str(self.id))
        self.stream = cv2.VideoCapture("rtsp://"+self.user+":"+self.passwd+"@"+self.ip)
        self.online = True
    def recuperarFrame(self):
        return self.frame ```


  


• What is video timescale, timebase, or timestamp in ffmpeg ? [on hold]

  11 avril 2017, par Please Help

  There does not seem to be any explanation online as to what these are. People talk about them a lot. I just want to know what they are and why they are significant. Using -video_track_timescale, how would I determine a number for it ? Is it random ? Should it be 0 ?

• How to make video loop properly ?

  28 mai 2019, par woopwoop399

  I want to play this video in a loop https://www.nicovideo.jp/watch/sm16617386 . I want to play an mp4 file in such a way, that whenever it gets to some point in the video (let’s say, 30.3 seconds), it will loop back (to for example 5.85 seconds).

  I tried to add this code in ffplay.c , it didn’t work well enough, I can hear the transition. I guess seeking isn’t fast enough, or audio needs to be looped in an independant way somehow.

  static void video_refresh(void *opaque, double *remaining_time)
  
  {
  
     (original code here...)
  
      time = get_master_clock(is);
  
      if (isnan(time))
  
          time = (double)is->seek_pos / AV_TIME_BASE;
  
      if (time > jump_when) {
  
          stream_seek(is, (int64_t)(6.0 * AV_TIME_BASE), (int64_t)(0.0 * AV_TIME_BASE), 0);
  
      }
  
  }

  My current plan is to just dig into ffmpeg, understand how video and audio decoders work, and savestate/loadstate the decoders.