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• How to deal ffplay being too slow playing iPhone's videos ?

  8 janvier 2020, par Mikhail T.

  Trying to play a 3840x2160 video recorded by an iPhone 7 (@30fps), I get frequent pauses — in the video, music keeps playing.

  



  This happens both in firefox and when ffplay is invoked to play the file directly — from command-line. The CPU is a dual E6700 @3.20GHz — not super fast, but it should be able to play smoothly, shouldn't it ? Video is Intel's "series 4" integrated chipset — again, not a speed-daemon, but it should be adequate... Support for Intel's VA API is included.

  



  I build ffmpeg-4.1 from source using FreeBSD port. As you can see, the port has a maddening amount of options — including several different ones for the 264-codec.

  



  Any suggestions for improving the decoding speed to the point, where it is watchable by a human ? Thank you !

  


• How to start and stop saving video frames according to a trigger with OpenCV VideoWriter

  11 août 2021, par Jacob nighFor

  I am building an app that records frames from IP camera through RTSP.

  



  My engine is in charge to save a video in mp4 with Opencv VideoWriter working well.
What I am looking for is to create a startRecord and a stopRecord class method that will respectively start and stop recording according to a trigger (it could be an argument that I pass to the thread).
Is anyone know what the best way to do that kind of stuff ?

  



  Here is my class :

  



  from threading import Thread
import cv2
import time
import multiprocessing
import threading
class RTSPVideoWriterObject(object):
    def __init__(self, src=0):
        # Create a VideoCapture object
        self.capture = cv2.VideoCapture(src)

        # Start the thread to read frames from the video stream
        self.thread = Thread(target=self.update, args=())
        self.thread.daemon = True
        self.thread.start()

    def update(self):
        # Read the next frame from the stream in a different thread
        while True:
            if self.capture.isOpened():
                (self.status, self.frame) = self.capture.read()

    def endRecord(self):
        self.capture.release()
        self.output_video.release()
        exit(1)

    def startRecord(self,endRec):

        self.frame_width = int(self.capture.get(3))
        self.frame_height = int(self.capture.get(4))
        self.codec = cv2.VideoWriter_fourcc(*'mp4v')
        self.output_video = cv2.VideoWriter('fileOutput.mp4', self.codec, 30, (self.frame_width, self.frame_height))
        while True:          
            try:
                self.output_video.write(self.frame)
                if endRec:
                    self.endRecord()
            except AttributeError:
                pass




if __name__ == '__main__':

    rtsp_stream_link = 'rtsp://foo:192.5545....'
    video_stream_widget = RTSPVideoWriterObject(rtsp_stream_link)

    stop_threads = False
    t1 = threading.Thread(target = video_stream_widget.startRecord, args =[stop_threads]) 
    t1.start() 
    time.sleep(15)
    stop_threads = True



  



  As you can see in the main I reading frames and store them in a separate thread. Then I am starting to record (record method is with an infinite loop so blocking) and then after 15 sec, I am trying to pass a 'stop_record' argument to stop recording properly.

  



  A part of the code comes from Storing RTSP stream as video file with OpenCV VideoWriter

  



  Is someone have an idea ?
I read a lot that OpenCV can be very tricky for multithreading

  



  N.

  


• openCV save frames from RTSP non blocking

  1er janvier 2020, par Jacob nighFor

  I am building an app that records frames from IP camera through RTSP.

  My engine is in charge to save a video in mp4 with Opencv VideoWriter working well.
  What I am looking for is to create a startRecord and a stopRecord class method that will respectively start and stop recording according to a trigger (it could be an argument that I pass to the thread).
  Is anyone know what the best way to do that kind of stuff ?

  Here is my class :

  from threading import Thread
  
  import cv2
  
  import time
  
  import multiprocessing
  
  import threading
  
  class RTSPVideoWriterObject(object):
  
      def __init__(self, src=0):
  
          # Create a VideoCapture object
  
          self.capture = cv2.VideoCapture(src)
  
  
  
          # Start the thread to read frames from the video stream
  
          self.thread = Thread(target=self.update, args=())
  
          self.thread.daemon = True
  
          self.thread.start()
  
  
  
      def update(self):
  
          # Read the next frame from the stream in a different thread
  
          while True:
  
              if self.capture.isOpened():
  
                  (self.status, self.frame) = self.capture.read()
  
  
  
      def endRecord(self):
  
          self.capture.release()
  
          self.output_video.release()
  
          exit(1)
  
  
  
      def startRecord(self,endRec):
  
  
  
          self.frame_width = int(self.capture.get(3))
  
          self.frame_height = int(self.capture.get(4))
  
          self.codec = cv2.VideoWriter_fourcc(*'mp4v')
  
          self.output_video = cv2.VideoWriter('fileOutput.mp4', self.codec, 30, (self.frame_width, self.frame_height))
  
          while True:          
  
              try:
  
                  self.output_video.write(self.frame)
  
                  if endRec:
  
                      self.endRecord()
  
              except AttributeError:
  
                  pass
  
  
  
  
  
  
  
  
  
  if __name__ == '__main__':
  
  
  
      rtsp_stream_link = 'rtsp://foo:192.5545....'
  
      video_stream_widget = RTSPVideoWriterObject(rtsp_stream_link)
  
  
  
      stop_threads = False
  
      t1 = threading.Thread(target = video_stream_widget.startRecord, args =[stop_threads]) 
  
      t1.start() 
  
      time.sleep(15)
  
      stop_threads = True

  As you can see in the main I reading frames and store them in a separate thread. Then I am starting to record (record method is with an infinite loop so blocking) and then after 15 sec, I am trying to pass a ’stop_record’ argument to stop recording properly.

  A part of the code comes from Storing RTSP stream as video file with OpenCV VideoWriter

  Is someone have an idea ?
  I read a lot that OpenCV can be very tricky for multithreading

  N.