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• Video Overlay not returning to black once video stopped

  24 septembre 2020, par Matt Nelson

  I am combining multiple videos from a webrtc call and aligning the "user-terminal" videos to the left, and the "user-visitor" videos to the right. As the visitor feed can start and strop, they have multiple videos so I'm offsetting them by the timestamp.

  


  This is working, however crazy it looks !

  


  The one last issue I have is that when the first visitor video stop on the right, it shows the last frame of that video until the next video starts on the left. Can I have it return o the black background ?

  


  Here is the command passed to ffmpeg :

  


  ffmpeg -y 
-i /recordings/process/5f6c9c3/videoroom-5f6c9c3-user-terminal-1600953586531366-audio.mjr.opus 
-i /recordings/process/5f6c9c3/videoroom-5f6c9c3-user-visitor-1600953592694430-audio.mjr.opus 
-i /recordings/process/5f6c9c3/videoroom-5f6c9c3-user-visitor-1600953609873223-audio.mjr.opus 
-i /recordings/process/5f6c9c3/videoroom-5f6c9c3-user-visitor-1600953628668227-audio.mjr.opus 
-i /recordings/process/5f6c9c3/videoroom-5f6c9c3-user-visitor-1600953663905342-audio.mjr.opus 
-i /recordings/process/5f6c9c3/videoroom-5f6c9c3-user-MasterTerminal-52350116-1600953681107272-audio.mjr.opus 
-i /recordings/process/5f6c9c3/videoroom-5f6c9c3-user-visitor-1600953697832165-audio.mjr.opus 
-i /recordings/process/5f6c9c3/videoroom-5f6c9c3-user-MasterTerminal-52350116-1600953723320364-audio.mjr.opus 
-i /recordings/process/5f6c9c3/videoroom-5f6c9c3-user-visitor-1600953725307043-audio.mjr.opus 
-filter_complex [1:a]adelay=6163|6163[1adelay];[2:a]adelay=23341|23341[2adelay];[3:a]adelay=42136|42136[3adelay];[4:a]adelay=77373|77373[4adelay];[5:a]adelay=94575|94575[5adelay];[6:a]adelay=111300|111300[6adelay];[7:a]adelay=136788|136788[7adelay];[8:a]adelay=138775|138775[8adelay];[0:a][1adelay][2adelay][3adelay][4adelay][5adelay][6adelay][7adelay][8adelay]amix=inputs=9:duration=longest[a] 
-map [a] -ac -2 /recordings/process/5f6c9c3/5f6c9c3.mp3


  


• Using FFMPEG, how do we add subtitles in the black bar area or under the video ?

  26 septembre 2020, par DunceDancer

  I followed these steps :

  


  


  1. Added the black bars

     


     -vf "scale=1920:1080:force_original_aspect_ratio=decrease,pad=1920:1080 :(ow-iw)/2 :(oh-ih)/2,setsar=1" Source :How to add black borders to video

     


  


  2. Added the subtitles ("burned" it into the video)

     


     ffmpeg -i "imput.mp4" -lavfi "subtitles=subtitles.srt:force_style='Alignment=0,OutlineColour=&H100000000,BorderStyle=3,Outline=1,Shadow=0,Fontsize=18,MarginL=5,MarginV=25'" -crf 1 -c:a copy "output.mp4" Source : ffmpeg subtitles alignment and position

     


  


  


  Now I am stuck as to how to place the subtitles under the video or in the black screen.

  


  Edit : Screenshot added to clarify

  


  Screenshot of the Problem

  


• 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.