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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 ?

• ffmpeg showwaves - Change color of waveform on top of an image

  15 août 2020, par Grant SYNKOP

  I need help with ffmpeg.

  



  I wrote this code :

  



  @echo off  
for %%F in (*.opus *.ogg) do 
(  
  ffmpeg -y -i "%%F" -loop 1 -i "default.jpg" -filter_complex " 
 [0:a]showwaves=s=2560x1440:mode=cline:r=30,colorkey=0x000000:0.01:0.1,format=yuva420p[v];
[1:v][v]overlay[outv]" -map "[outv]" -pix_fmt yuv420p -map 0:a -vcodec libvpx-vp9 -lossless 1 -speed 8 -acodec copy -shortest "%%~nF.webm" 
)


  



  What it does is that for each .opus or .ogg audio file, it'll output a video with a default.jpg background image (which is completely white) and a waveform on top of it, with the audio playing.
Problem is, I would change the color of the waveform to black, but I don't understand how colorkey works even after reading the documentation...

  



  Basically, I want to obtain something like this (but the waveform being in black) : https://www.youtube.com/watch?v=k9arneFijG8

  



  Thanks in advance.