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• Extracting frames from a video created by muxing a bunch of images together is changing the integrity of the frames [closed]

  13 mars 2023, par dreamersparadox

  I am trying to transfer a bunch of images as a video. What I am doing is simply muxing these static images into a video using the following commands.

  



  ffmpeg -framerate 1 -i %02d.jpg -codec copy 1.mkv


  



  After this, I verify the integrity of my static images and the frames in the video using -

  



  ffmpeg -i %02d.jpg -f framehash -


  



  and

  



  ffmpeg -i 1.mkv -map 0:v -f framehash -


  



  I get the same hashes so it means I have archived the images properly. Now next I send this video to my friend who extracts the frames using -

  



  ffmpeg -i 1.mkv mkv%02d.jpg 


  



  Now after extracting the hashes don't remain the same that means the integrity is lost.

  



  How to extract the frames as it is so that integrity is not lost ?

  



  Also if you any other way to achieve what I am trying, please advice.

  



  Here are the hashes.

  


• How to detect a surge of activity in a video ?

  22 mars 2019, par Alain Collins

  I’d like to automatically detect a surge of activity in a video, e.g. basketball jump shot, hockey face-off, sprinters starting, etc., preferably using ffmpeg.

  In these instances, there’s some motion as the players assume their positions, followed by a pause as they wait for the ref to throw the ball or drop the puck, followed by a lot of motion as all players begin to react. It’s also typical that the camera will be still during this period and begin moving as the ball or puck changes position.

  I’ve tried using the ’select’ filter select='gt(scene,0.4)', but that seems to be more concerned with scene changes (i.e., more dramatic changes) even with low thresholds.

  I also tried exporting the scene information and examining it manually, but couldn’t find a clear pattern that correlated with motion in the video.

  UPDATE : I ran a mestimate on the video. Processing took a long time, but there was definitely a change in activity before and at point of interest. Is there a way to export this information to a file, or otherwise detect the amount of motion seen my mestimate ?

• http-flv live broadcast with flv.js error

  29 mars 2019, par Forest Yang

  When I try nginx + nginx-http-flv-module + flv.js to play video from camera, error happened, but play with VLC works fine.

  log in nginx :

  flv live: app args MUST be specified, client: 192.168.89.1, server: myserver, request: "GET /live.html HTTP/1.1", host: "192.168.89.134:8080"

  Some key configurations,

  nginx.conf :

  http{
  
     ...
  
     server{
  
     ...
  
      location /live {
  
              flv_live on;
  
              chunked_transfer_encoding  on; #open 'Transfer-Encoding: chunked' response
  
              add_header 'Access-Control-Allow-Origin' '*'; #add additional HTTP header
  
              add_header 'Access-Control-Allow-Credentials' 'true'; #add additional HTTP header
  
          }
  
  
  
      }
  
  }
  
  
  
  rtmp {
  
      server {
  
          listen 1935;
  
          server_name 192.168.89.134;
  
  
  
          application myapp {
  
              live on;
  
              gop_cache on; 
  
            }
  
      }
  
  }

  ffmpeg command :

  ffmpeg -f avfoundation -s 1280x720 -r 30  -i 0 -f flv rtmp://192.168.89.134:1935/myapp/test

  VLC network url :

  http://192.168.89.134:8080/live?port=1935&app=myapp&stream=test

  HTML with flv.js :

  if (flvjs.isSupported()) {
  
              var videoElement = document.getElementById('videoElement');
  
              var flvPlayer = flvjs.createPlayer({
  
                  type: 'flv',
  
                  'isLive': true,
  
                  url: 'http://192.168.89.134:8080/live?port=1935&app=myapp&stream=test'
  
              });
  
              flvPlayer.attachMediaElement(videoElement);
  
              flvPlayer.load();
  
              flvPlayer.play();
  
          }

  Can anyone tell me why based your experience ? thank you.