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• How to show part of a frame from a 4k IP cam

  15 avril 2022, par BrP

  I'm working with andoroid.js framework to create a simple app that will show the video that is streamed from some IP cam.

  


  I want to add the ability for the user to see only a part of the full video frame that have a resolution of 4k, so for example, if the user want to see the upper left corner of the frame, he can see it like the image is magnified. I'm not sure if this is possible.

  


  Is there any ffmpeg or any way to accomplish this with a library for node ? Can I include ffmpeg with node_modules when I build my app ?

  


• How to buffer videojs so preload won't show ?

  9 septembre 2015, par toy

  I’m building video cutting tool using videojs. In order to give the feedback to user right away instead of using ffmpeg to merge the video right away. I just swap the videos instead. However, during the swapping you would see the loading icon when the second video is being loaded. Is there any tricks that would tell videojs to load the video before so when the video plays it would just play right away.

  http://jsfiddle.net/noppanit/odwqqoss/2/

  Here’s my code

  <div>
  
      <video preload="auto" class="vjs-tech" src="http://www.w3schools.com/html/mov_bbb.mp4">
  
          <source src="http://www.w3schools.com/html/mov_bbb.mp4" type="video/mp4">
  
      </source></video>
  
  </div>
  
  <div>
  
      <div>
  
          <label>From</label>
  
          <input type="text" class="start-time" />
  
      </div>
  
      <div>
  
          <label>To</label>
  
          <input type="text" class="stop-time" />
  
      </div>
  
      <div>
  
          <input type="button" value="Select" />
  
      </div>
  
  </div>
  
  <div>
  
      <video preload="auto" class="vjs-tech" src="http://www.w3schools.com/html/mov_bbb.mp4">
  
          <source src="http://www.w3schools.com/html/mov_bbb.mp4" type="video/mp4">
  
      </source></video>
  
  </div>
  
  <div>
  
      <div>
  
          <label>From</label>
  
          <input type="text" class="start-time-video1" />
  
      </div>
  
      <div>
  
          <label>To</label>
  
          <input type="text" class="stop-time-video1" />
  
      </div>
  
      <div>
  
          <input type="button" value="Select" />
  
      </div>
  
  </div>
  
  <div>
  
      <input type="button" value="Cut!" />
  
  </div>
  
  <div></div>
  
  
  
  
  
  
  
  
  
      (function ($) {
  
      $('#cut-video').on('click', function () {
  
          var video = videojs("example_video_1");
  
          var startTime = $('.start-time');
  
          var stopTime = $('.stop-time');
  
          video.currentTime(startTime.val());
  
          video.play();
  
          video.on('timeupdate', function (e) {
  
              if (video.currentTime() >= stopTime.val()) {
  
                  video.pause();
  
              }
  
          });
  
  
  
      });
  
  
  
      $('#cut-video1').on('click', function () {
  
          var video = videojs("example_video_2");
  
          var startTime = $('.start-time-video1');
  
          var stopTime = $('.stop-time-video1');
  
          video.currentTime(startTime.val());
  
          video.play();
  
          video.on('timeupdate', function (e) {
  
              if (video.currentTime() >= stopTime.val()) {
  
                  video.pause();
  
              }
  
          });
  
      });
  
  
  
      $('#cut').on('click', function () {
  
          var video = $('<video></video>');
  
          video.attr('id', 'result1');
  
          video.addClass('video-js vjs-default-skin');
  
          video.attr('width', 300);
  
  
  
          var source = $('<source></source>');
  
          source.attr('src', 'http://www.w3schools.com/html/mov_bbb.mp4');
  
          source.attr('type', 'video/mp4');
  
  
  
          video.append(source);
  
          $('#result').append(video);
  
  
  
          var player = videojs("result1");
  
          var startTime = $('.start-time');
  
          var stopTime = $('.stop-time');
  
  
  
          player.currentTime(startTime.val());
  
          player.play();
  
  
  
          player.on('timeupdate', function (e) {
  
              if (player.currentTime() >= stopTime.val()) {
  
                  player.src({
  
                      "type": "video/mp4",
  
                      src: 'http://www.w3schools.com/html/mov_bbb.mp4'
  
                  });
  
                  var startTime1 = $('.start-time-video1');
  
                  var stopTime1 = $('.stop-time-video1');
  
  
  
                  player.currentTime(startTime1.val());
  
                  player.play();
  
                  player.on('timeupdate', function (e1) {
  
                      if (player.currentTime() >= stopTime1.val()) {
  
                          player.pause();
  
                      }
  
                  });
  
              }
  
          });
  
  
  
  
  
  
  
  
  
      });
  
  
  
  })(jQuery);

• ffprobe does not show packet size of a mpeg transport stream as 188 bytes

  16 octobre 2015, par CompNet

  I created a transport stream from a H.264 encoded file using the following ffmpeg command :

  ffmpeg -i encoded.mp4 -c copy -map 0 -vbsf h264_mp4toannexb mpegts sample.ts

  Now I want to check the frames and packets within the transport stream. I used

  ffprobe -show_frames

  which shows the frame details for audio and video frames. But I’m confused about the pkt_size field. Is it the actual frame size of each elementary stream of audio and video (I/B/P frames) ?

  Also, when I run

  ffprobe -show_packets

  is it supposed to give each packet details in the transport stream ? Because the size field of each packet is not 188 bytes, rather it is same as the pkt_size I got with -show_frames.

  Could someone please explain why the size in -show_packets of transport stream is not 188 bytes ? Did I do anything wrong while multiplexing mp4 to TS ?