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• FFmpeg convert video to images with complex logic

  18 juillet 2020, par Udi

  I'm trying to use FFMPEG in order to solve some complex logic on my videos.

  


  The business logic is the following :
I get videos from the formats : avi, mp4, mov.

  


  I don't know what is the content in the video. It can be from 1M to 5G.

  


  I want to output a list of images from this video with the higher quality I can get. Capturing only frames that have big changes from their previous frame. (new person, a new angle, big movement, etc)

  


  In addition, I want to limit the number of frames per second that even if the video is dramatically fast and has changed all the time it will not produce more frames per second than this parameter.

  


  I'm using now the following command :

  


  ./ffmpeg -i "/tmp/input/fast_movies/3_1.mp4" -vf fps=3,mpdecimate=hi=14720:lo=7040:frac=0.5 -vsync 0 -s hd720 "/tmp/output/fast_movies/(#%04d).png"


  


  According to my understanding it doing the following :
fps=3 - first cut the video to 3 frames per second (So that is the limit I talked about)

  


  mpdecimate - filter frames that doesn't have greater changes than the thresholds I set.

  


  -vsync 0 - sync video timestamp - I'm not sure why but without it - it makes hundereds of duplicate frames ignoring the fps and mpdecimate command. Can someone explain ?

  


  -s hd720 - set video size to

  


  It works pretty well but I'm not so happy with the quality. Do you think I miss something ? Is there any parameter in FFMPEG that I better use it instead of these ones ?

  


• Ffmpeg 2 Input cameras in single ouput

  1er juin 2020, par Expressingx

  I have app where it streams from a camera to a file with Preview using liabv. 
Now there is requirement to be able to stream from 2 cameras simultaneously and output to a single file. The Preview will be like a CCTV camera and written to single output. Is this possible with libav ?
Before doing anything I've tried with ffmpeg.exe directly and found this :

  



  ffmpeg -f dshow -i video="Camera1" -i video="Camera2" -filter_complex "nullsrc=size=640x480 [base];[0:v] setpts=PTS-STARTPTS, scale=640x480 [upperleft];[1:v] setpts=PTS-STARTPTS, scale=640x480 [upperright];[base][upperleft] overlay=shortest=1 [tmp1];[tmp1][upperright] overlay=shortest=1:x=640:y=480 [tmp2];"-c:v libx264 output.mp4


  



  But every time throws error 'No such file or directory' for the second camera, while I've verified the camera is working if I use it as single input. Do I miss something ?

  



  Overall is it possible to achieve that ?

  


• RTSP Streaming on Jetson Xavier NX, Ubuntu 20.04 [closed]

  12 décembre 2023, par Jan

  i am working on a project, where i want to create a rtsp live server from a USB Camera.
To do that i downloaded the mediamtx rtsp server.

  


  Then i am pushing the stream from the camera to the rtsp server, and display it using ffplay, or OpenCV in C++.

  


  This is working, however i get a very low quality, and a delay of up to 1 second.

  


  Is there any way to improve the delay ? If possible i would like to have the same quality and delay as if i read it with gst-launch-1.0.

  


  The command for ffmpeg was

  


  ffmpeg -i /dev/video0 -s 1280x720 -vsync 0 - f rtsp rtsp://localhost:8554/mystream


  


  I also tried to utilize the hardware acceleration with cuda

  


  ffmpeg -i /dev/video0 -s 1280x720 -vsync 0 -hwaccel cuda -hwaccel_output_format cuda -f x11grab -fflags nobuffer -i :0.0+0.0 -preset ultrafast -vcodec libx264 - tune zerolatency -g 1 -omit_video_pes_length 0 - f rtsp rtsp://localhost:8554/mystream


  


  With this I get a better quality, but the delay is still very bad.

  


  Any ideas on how to get a live stream with < 100ms ?&#xA;Did I maybe miss out some additional parameters for ffmpeg that resolve that problem ?

  &#xA;