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• Delay in video playback. Not able to identify the cause - AWS S3 region / ffmpeg / Videojs

  17 septembre 2016, par Himansu Kisan

  We are not able to identify the cause for random behavior while playing video on our website. (Sorry, cant share a link since the videos are for registered users only)
  The videos sometimes plays instantly and sometimes it takes over 1 minute to start. Not sure what we are doing wrong.

  We are using AWS S3 Oregon region (not the closest to target region, but it is cheaper) to store video files.
  The video files are encoded using ffmpeg. Below is the syntax

  ffmpeg -i input.mts -codec:v libx264 -threads 4 -movflags +faststart -profile:v high -preset slow -b:v 500k -maxrate 500k -bufsize 1000k -vf scale="trunc(oh*a/2)*2:720" "output.mp4"

  ffmpeg -i input.mts -codec:v libvpx -threads 4 -quality good -cpu-used 5 -b:v 500k -maxrate 500k -bufsize 1000k -qmin 10 -qmax 42 -vf scale="trunc(oh*a/2)*2:720" -codec:a libvorbis -b:a 128k "output.webm"

  On website, we are using Videojs 5.10.8.
  Below is the code snippet

   <video class="video-js vjs-default-skin vjs-big-play-centered" preload="none" controls="controls" poster="abcd.jpg" style="width:100%;height:100%;min-height:360px;" data-setup="{&quot;autoplay&quot;:true}">
  
  <source src="abcd.mp4" type="video/mp4"></source>
  
  <source src="adcd.webm" type="video/webm"></source>
  
  <p class="vjs-no-js">
  
      To view this video please enable JavaScript, and consider upgrading to a web browser
  
      that <a href="http://videojs.com/html5-video-support/" target="_blank">supports HTML5 video</a>
  
  </p>
  
  </video>

  What are we doing wrong ? Please help us out.

• avcodec/ttmlenc : add support for region positioning and sizing

  29 mars 2021, par Jan Ekström

  avcodec/ttmlenc : add support for region positioning and sizing
  The ASS margins are utilized to generate percentual values, as
  
  the usage of cell-based sizing and offsetting seems to be not too
  
  well supported by renderers.
  Signed-off-by : Jan Ekström <jan.ekstrom@24i.com>
  

  • [DH] libavcodec/ttmlenc.c
  • [DH] tests/ref/fate/sub-ttmlenc

• Is it possible to adjust position of gdigrab recording region during recording ?

  30 novembre 2020, par adelima

  I'm using ffmpeg for recording video from defined desktop region by starting ffmpeg.exe as process with arguments like so :

  


      public static void StartRecording(Video v) {
        string outPath = Path.Combine(Application.StartupPath, "rec", $"{v.FileName}.mkv");
        v.FFMPEG = new Process {
            StartInfo = new ProcessStartInfo() {
                Arguments = $"-hide_banner -y -thread_queue_size 512 -f gdigrab -offset_x {v.Bounds.X} -offset_y {v.Bounds.Y} -video_size {v.Bounds.Width}x{v.Bounds.Height} -show_region 0 -i desktop -vf \"scale=trunc(iw/2)*2:trunc(ih/2)*2\" -c:v libx264 -preset ultrafast -crf 18 -pix_fmt yuv420p \"{outPath}\"",
                WindowStyle = ProcessWindowStyle.Hidden,
                CreateNoWindow = true,
                UseShellExecute = false,
                FileName = Path.Combine(Application.StartupPath, "bin", "ffmpeg.exe"),
                RedirectStandardOutput = true,
                RedirectStandardInput = true,
                RedirectStandardError = true,
            }
        };
        v.FFMPEG.Start();

        new Thread(() => {
            using(StreamReader sr = v.FFMPEG.StandardError) {
                while(!sr.EndOfStream) {
                    Debug.WriteLine(sr.ReadLine());
                }
            }
        }).Start();
    }

    public static void StopRecording(Video v) {
        using(StreamWriter sw = v.FFMPEG.StandardInput) {
            sw.WriteLine("q\n");
        }
        v.FFMPEG.WaitForExit();
        v.FFMPEG.Dispose();
    }


  


  Is it possible to make changes to the -offset_x and -offset_y arguments during recording ? I'm drawing the recording region bounds with directx and want to add a titlebar to it which can be dragged to move the recording region, but I'm not sure how I would let ffmpeg know that I want these offsets changed or whether it's even possible.