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• How to play video file with 720x480 and 60fps on ipad using ffmpeg

  12 septembre 2011, par akash

  I can play video files with 320x180 resolution on ipad but files with more than 320x180 and 60fps are playing slowly. anybody can tell what will be the issue.?

  is iOS supports playback of files with 60fps ?

  Regards
  NewBee

• Play HLS segments through Media source extensions

  11 février 2018, par ler

  I got a list of m4s and init.mp4 from this FFMPEG command

  ffmpeg -i bunny.mp4 -f hls -hls_segment_type fmp4 -c:v copy playlist.m3u8

  I send those chunks using Socketand try to play them through MSE.
  When i send them in this order :

  init.mp4 + playlist0.m4s + playlist1.m4s ...

  They play without any problem, But when i want to start from the chunk number 3 meaning init.mp4 + playlist3.m4s for example i get this error :

  video frame with PTS 0us has negative DTS -80000us after applying timestampOffset, handling any discontinuity, and filtering against append window.

  I want to be able to start from any chunk, currently the only way to play the video is to star by init.mp4 + playlist0.m4s meaning playlist0.m4s because init.mp4 contain just headers of the video, This is the client code i’m using :

  var socket = io();
  
  var video = document.querySelector('video');
  
  var mimeCodec = 'video/mp4; codecs="avc1.64000d,mp4a.40.2"'; // true
  
  if ('MediaSource' in window && MediaSource.isTypeSupported(mimeCodec)) 
  
  {
  
      var mediaSource = new MediaSource;
  
      video.src = URL.createObjectURL(mediaSource);
  
      mediaSource.addEventListener('sourceopen', function () {
  
              var mediaSource = this;
  
              var sourceBuffer = mediaSource.addSourceBuffer(mimeCodec);
  
             sourceBuffer.mode = 'segments'; 
  
              sourceBuffer.addEventListener('updateend', function (_) { video.play().then(function() { }).catch(function(error) { }); });
  
              socket.on('broadcast', function (chunk) {
  
                  downloadData(chunk.uri, function(arrayBuffer) {
  
                      sourceBuffer.appendBuffer(arrayBuffer);
  
                  });
  
              });
  
      });
  
  } else {
  
      console.error('Unsupported MIME type or codec: ', mimeCodec);
  
  }
  
  function downloadData(url, cb) {
  
      var xhr = new XMLHttpRequest;
  
      xhr.open('get', url);
  
      xhr.responseType = 'arraybuffer';
  
      xhr.onload = function () {
  
          cb(new Uint8Array(xhr.response));
  
      };
  
      xhr.send();
  
  }

• VideoWriter OpenCV - cannot put pipeline to play in function CvVideoWriter_GStreamer::open

  24 octobre 2019, par 021

  Almost exactly the same question : OpenCV error - cannot put pipeline to play in function CvVideoWriter_GStreamer::open

  Context : I’m trying to create a video and save it in a .avi file with OpenCV 3.3.0 and Python 2.7.

  Problem : This code :

  fourcc = cv2.VideoWriter_fourcc(*'XVID')
  
  out = cv2.VideoWriter('data/out/output.avi', fourcc, 30, (800, 600))

  Raises :

  (python2.7:12345): GStreamer-CRITICAL **: gst_element_make_from_uri: assertion 'gst_uri_is_valid (uri)' failed
  
  
  
  ** (python2.7:12345): CRITICAL **: gst_ffmpeg_cfg_set_property: assertion 'qdata->size == sizeof (gint64)' failed 
  
  OpenCV Error: Unspecified error (GStreamer: cannot put pipeline to play ) in CvVideoWriter_GStreamer::open, file /soft/OpenCV3.3/opencv-3.3.0/modules/videoio/src/cap_gstreamer.cpp, line 1690
  
  VIDEOIO(cvCreateVideoWriter_GStreamer (filename, fourcc, fps, frameSize, is_color)): raised OpenCV exception:
  
  
  
  cap_gstreamer.cpp:1690: error: (-2) GStreamer: cannot put pipeline to play
  
   in function CvVideoWriter_GStreamer::open

  Question : How do I solve this problem so I can write video files with OpenCV ?