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• avcodec/mpegvideo_enc : Call ff_h261_encode_init() earlier

  2 octobre 2022, par Andreas Rheinhardt

  avcodec/mpegvideo_enc : Call ff_h261_encode_init() earlier
  It does not require anything that is being set between
  
  the new position where it is called and the old position
  
  where it used to be called ; and nothing that it sets
  
  gets overwritten between these two positions.
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
  

  • [DH] libavcodec/mpegvideo_enc.c

• automatically show blue screen in ffmpeg when live video source disconnects

  13 janvier 2015, par user1913115

  i’m capturing a live source using ffmpeg :

  ffmpeg -i rtsp://192.168.1.143/source -codec copy output.mp4

  which works great. the ip address is an address of an RTSP proxy server which takes in the camera itself as the source. i.e. my setup :

  camera ->> RTSP proxy ->> ffmpeg(output)

  if camera disconnects (accidentally or on purpose) the recording stops (obviously) and only continues when I re-connect the camera.

  Question : is there a way for ffmpeg to ’fill’ the down time with blue screen or green screen of some sort ?
  i know i can ’play’ a still image of a green screen using ffmpeg to record an mp4 out of it :

  ffmpeg -loop 1 -y -re -i green.jpg -r 30 -vcodec libx264 -an -f h264 greenvideo.mp4

  so i could set it up this way :

  ffmpeg(green) ->> ffmpeg(output)

  but I would need to run the command manually. is there a way for ffmpeg(output) to automatically detect the disconnect and use green.jpg as a ’video’ source ? or i can even create a 5-minute green.mp4 video of just green screen.

  put it another way, is it possible for ffmpeg to automatically switch input sources if one goes down ?

• Capture and play MJPEG - Network Video stream over UDP with OpenCV and ffmpeg

  3 mars 2016, par MoNas

  I’m trying to receive and display a udp live mjpeg - network video stream from a network cam.
  I can play the video stream by starting VLC with the Argument --demux=mjpeg and then typing udp://@:1234 in the network stream field. Or with gstreamer by the console line : gst-launch -v udpsrc port=1234 ! jpegdec ! autovideosink. My Cam has the IP Address 192.168.1.2 and it sends the stream to the address 192.168.1.1:1234.

  I’ve tried to capture the stream with OpenCV with :

  cv::VideoCapture cap;
  
  cap.open("udp://@192.168.1.1:1234");

  I tried also :

  cap.open("udp://@:1234")
  
  
  
  cap.open("udp://@localhost:1234")
  
  
  
  cap.open("udp://192.168.1.1:1234")
  
  
  
  cap.open("udp://192.168.1.1:1234/")

  But the function hangs until I press ctrl+C. I have the same problem when I use ffmpeg with : ffmpeg -i udp://@192.168.1.1:1234 -vcodec mjpeg

  What did I do wrong ? When i installed ffmpeg i couldn’t install the dependency libsdl1.2-dev. Is that the problem ?

  If so, there is any way to read the udp-frames from the socket and then decode the JPEG pictures and display it with OpenCV ?

  I have the OS Ubuntu linaro oneiric 11.10 with the kernel 3.0.35 from Freescale