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• Delay/Lag in OpenCV VideoCapture

  18 mars 2021, par user244791

  I'm trying to read an rtsp stream from an ip camera using opencv's VideoCapture Class on Ubuntu 20.04 with opencv 4.5. There is a lag in the video on ubuntu but none when I run the same code on a windows 10 machine.

  


  cap.set(cv2.CAP_PROP_BUFFERSIZE, size) returns false and the cameras default buffer size does not change.

  


  cap = cv2.VideoCapture("rtsp://admin:@dmin123@192.168.1.64")
while (cap.isOpened()):
    ret, frame = cap.read()
    cv2.imshow("Live", frame)
    if cv2.waitKey(1) & 0xFF == ord('q'): #press q to quit
        break
cap.release()


  


  The stream works well when I play it using ffplay with the following parameters :

  


  '''ffplay -fflags nobuffer -flags low_delay -tune zerolatency -framedrop -rtsp_transport tcp "rtsp ://192.168.1.64"'''

  


  Need help on how to reduce/handle the lag in my code.

  


• Executing a batch file on a remote server

  2 février 2018, par Mitchell Day

  I have an IIS server with Php and have been trying to execute scripts using exec() and system() with no luck. When i go to the machine and run it by double clicking it, or by opening command and running the batch file, 4 windows pop open with ffmpeg streams going and dump to folder.

  With exec("cmd.exe 'c:\inetpub\wwwroot\estf\batch\srRecord.bat'");
  I am getting some of the batch file process working (creates new folder and dumps to file, but i can’t see the cmd gui anywhere. And my stop.bat won’t taskkill the ffmpeg process.

  Is there a way to bring up the cmd GUI on the external device, also a way to run the exec() command and pass on so that other devices or batch files can kill these tasks (i am thinking that because the php is still running it, nothing else has rights to stop it.

  Regards,

  Mitchell

• ffmpeg : advice on params to speed up converting to mp4 ?

  2 août 2022, par DapperDanh

  I am trying to minimize the time it takes to convert an input video file of various extensions to a mp4 file.

  


  Right now, I am simply using this :

  


  ffmpeg -y -i {inputFileName} convertOutput.mp4


  


  I have followed some advice on various forums, but nothing I change seems to impact the overall timing. Adding present flags does not seem to help me on my machine.

  


  For ex, all 3 of the following take roughly 10 seconds.

  


  ffmpeg -y -i "C:\_eraseme\ffmpeg\Wildlife.wmv" "C:\_eraseme\ffmpeg\Wildlife.mp4" 

ffmpeg -y -i "C:\_eraseme\ffmpeg\Wildlife.wmv" "C:\_eraseme\ffmpeg\Wildlife.mp4" -deadline realtime -cpu-used -16

ffmpeg -y -i "C:\_eraseme\ffmpeg\Wildlife.wmv" "C:\_eraseme\ffmpeg\Wildlife.mp4" -preset ultrafast


  


  I am hoping that maybe the fact I am always converting to mp4 there are some additional parameters that might make an impact ?

  


  Any suggestions or links one could recommend ?
Thanks,
Dan