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• Streaming Encoded MPEG-4 live video from a web camera using RTP in C++

  20 juin 2022, par Maad A.Galil

  I have been working on building a video streamer from a webcam using RTP protocol in C++ language in Linux. I was able to use opencv to take frames from the webcam and send them frame by frame to a client app that shows those frames one by one using the same frame per second parameter.

  


  But that is mostly a MJPEG kind of transfer as the encoding used is JPEG encoding with a specific quality for each frame. However, I would like to use MPEG-4 encoding before transferring the video. After a deep search online I found out that ffmpeg is the best for such purpose. But the samples online mostly work through a command line interface to capture a webcam video and save it as a video file with the given encoding and format.

  


  Is there a possibility to encode the webcam "LIVE", and get byte data while encoding the camera stream ?

  


  I would like to use those byte data to transfer it using RTP for example. And then I would like to decode the received byte data and show the video using opencv imshow function for example.

  


• How can I solve this error, file not found error

  11 août 2021, par Kapil Kumar

  from pydub import AudioSegment
sound = AudioSegment.from_mp3("F :\work\online internship\M1ML\Language_Recg\Test.mp3")
sound.export("F :\work\online internship\M1ML\Language_Recg\Test.wav", format="wav")

  


  C :\Users\hp\anaconda3\envs\Language_Recg\python.exe "F :/work/online internship/M1ML/Language_Recg/mp3_wav.py"
C :\Users\hp\anaconda3\envs\Language_Recg\lib\site-packages\pydub\utils.py:170 : RuntimeWarning : Couldn't find ffmpeg or avconv - defaulting to ffmpeg, but may not work
warn("Couldn't find ffmpeg or avconv - defaulting to ffmpeg, but may not work", RuntimeWarning)
C :\Users\hp\anaconda3\envs\Language_Recg\lib\site-packages\pydub\utils.py:198 : RuntimeWarning : Couldn't find ffprobe or avprobe - defaulting to ffprobe, but may not work
warn("Couldn't find ffprobe or avprobe - defaulting to ffprobe, but may not work", RuntimeWarning)
Traceback (most recent call last) :
File "F :/work/online internship/M1ML/Language_Recg/mp3_wav.py", line 2, in 
sound = AudioSegment.from_mp3("F :\work\online internship\M1ML\Language_Recg\Test.mp3")
File "C :\Users\hp\anaconda3\envs\Language_Recg\lib\site-packages\pydub\audio_segment.py", line 796, in from_mp3
return cls.from_file(file, 'mp3', parameters=parameters)
File "C :\Users\hp\anaconda3\envs\Language_Recg\lib\site-packages\pydub\audio_segment.py", line 728, in from_file
info = mediainfo_json(orig_file, read_ahead_limit=read_ahead_limit)
File "C :\Users\hp\anaconda3\envs\Language_Recg\lib\site-packages\pydub\utils.py", line 274, in mediainfo_json
res = Popen(command, stdin=stdin_parameter, stdout=PIPE, stderr=PIPE)
File "C :\Users\hp\anaconda3\envs\Language_Recg\lib\subprocess.py", line 858, in init
self._execute_child(args, executable, preexec_fn, close_fds,
File "C :\Users\hp\anaconda3\envs\Language_Recg\lib\subprocess.py", line 1311, in _execute_child
hp, ht, pid, tid = _winapi.CreateProcess(executable, args,
FileNotFoundError : [WinError 2] The system cannot find the file specified

  


  Process finished with exit code 1

  


• 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 ```