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• lavr : only save/restore the mixing matrix if mixing is being done

  30 novembre 2012, par Justin Ruggles

  lavr : only save/restore the mixing matrix if mixing is being done

• Save incoming frames from camera to video using ffmpeg

  12 avril 2024, par Liza Yemini

  I'm trying to record frames that I read from an industrial camera (such as - https://en.ids-imaging.com/store/u3-3680xle.html) in my C# code as bitmaps.
I want to convert those bitmaps to video on the fly.

  


  My solution until now was -> Sending those bitmaps to a virtual camera (e2e soft vcam) and then record the camera with ffmpeg - using this command :

  


  -f dshow -i video=VCam -r 18 -vcodec libx264 Video.mp4


  


  This is not working so well, because there are drop frames and the video is not smooth.

  


  There is another way to use ffmpeg for converting those images to video on the flight ?

  


  Thank you !

  


• Video streaming FFMPEG - VLC video starts black

  7 novembre 2020, par xKedar

  I am trying to stream my webcam when an event occurs to another machine.
Giving the fact that FFMPEG needs around 2 seconds since I call it to when it starts streaming I'm running it in background sending everything to a local socket that consumes it until the event happens and then I reverse the data to the other machine

  


  Here I capture the camera

  


  class ffmpegThread (Thread):
    def __init__(self):
        Thread.__init__(self)
     
    def run(self):
        cam, mic = detect_devices()
        command = 'ffmpeg -f dshow -i video='+cam+':audio='+mic+' -profile:v high -pix_fmt yuvj420p -level:v 4.1 -preset ultrafast -tune zerolatency -vcodec libx264 -r 14 -b:v 512k -s 240x160 -acodec aac -ac 2 -ab 32k -ar 44100 -f mpegts -flush_packets 0 udp://127.0.0.1:'+str(config.ffmpeg_port)+'?pkt_size=1316'
        p = Popen(command , stderr=PIPE)
        for line in iter(p.stderr.readline,''):
           if config.end: break
        p.terminate()
        return 0


  


  This is where I receive and forward the video

  


  
class sendVideoThread (Thread):
    def __init__(self, UDPsenderSocket):
        Thread.__init__(self)
        self.UDPsenderSocket = UDPsenderSocket
 
    def run(self):
        sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
        sock.bind(("127.0.0.1", config.ffmpeg_port))
        bufferSize  = 1348
        firstData = sock.recvfrom(bufferSize)
        while True:
            data = sock.recvfrom(bufferSize)
            if config.event == True:
                startTime = time.time()
                self.UDPsenderSocket.sendto(firstData[0], config.address)
                while time.time() - startTime < 14:
                    self.UDPsenderSocket.sendto(data[0], config.address) 
                    data = sock.recvfrom(bufferSize)                    
                config.event= False
            if config.end: sys.exit()



  


  And those are the vlc options on the other machine(not the whole code)

  


      def play(self):
        self.player = vlc.Instance(["--file-caching=0 --network-caching=0"]).media_player_new()
        self.player.set_mrl('udp://@0.0.0.0:'+str(config.vlcPlayer_port))
        self.player.set_hwnd(self.frame.winfo_id())
        self.player.audio_set_mute(False)
        self.player.play()



  


  The video reaches the other machine but it starts black with audio-only for some seconds then it starts working fine. I guess that by sending the video from a random moment(frame) when the event happens it may happen that vlc will miss some information about the video and needs the next frame with information to come in order to show the video, I was looking to something in order to have more frames with that info but I was not able to find it.