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• HTML5 live streaming with alpha channel

  5 mars 2021, par air5

  We are trying to live stream a video file with alpha channel. Adaptive streaming would be great, but it's not a must. Streaming is pretty new territory for us.

  


  We found out that WebM (VP9) seems to be the only format in the web that supports alpha channel. We tried using the nginx-rtmp-module as streaming server (MPEG-DASH) and broadcast the file with ffmpeg. But the alpha channel was lost. Probably because RTMP required us to broadcast the video as a FLV which doesn't support alpha.

  


  Is anyone having experience in streaming rgba videos on the web ? Getting to know compatible commercial solutions would be interesting tee. My next approaches would be trying to use Icecast. There is not much information online but this article where streaming a webm directly seems to be possible.

  


• How to display live frame rate on top of video using ffmpeg ? [closed]

  2 juin 2021, par walking lime

  I want to display live frame rate over video using ffmpeg.I am using following command to get the frame number.Is it possible to get the frame rate as well ?.Thanks.

  


  ffmpeg -re -stream_loop -1 -i /dev/video0 -c:v libx264 -preset veryfast -tune zerolatency -profile:v baseline -pix_fmt yuv420p -bf 0 -x264-params keyint=30:scenecut=0 -vf "drawtext=fontfile=/usr/share/fonts/truetype/freefont/FreeMonoBold.ttf: text='%{frame_num}': start_number=1: x=(w-tw)/2: y=h-(2*lh): fontcolor=black: fontsize=20: box=1: boxcolor=white: boxborderw=5"   -an -f mpegts udp://localhost:4000?pkt_size=1316


  


• Reading live output from FFMPEG using PHP

  29 septembre 2018, par user561787

  the problem i’m dealing with is getting the shell output from a ffmpeg command while it’s being executed and writing it in an html page using php.

  After some research i found a very similar request here :Update page content from live PHP and Python output using Ajax, which seemed to be perfect, but it’s not working at all.

  The basic idea is to use an AJAX request to invoke the PHP script, which should execute the command and echo the live read content from the process, taking care to use this.readyState==3 (otherwise the JS script would receive the response only upon completion)

  For the PHP section i tried using the code in the answer above, (obviously adapted to my needs) :

  function liveExecuteCommand($command){
  
  
  
      while (@ ob_end_flush()); // end all output buffers if any
  
  
  
      $proc = popen($command, 'r');
  
  
  
      $live_output     = "";
  
      $complete_output = "";
  
  
  
      while (!feof($proc))
  
      {
  
          $live_output     = fread($proc, 4096);
  
          $complete_output = $complete_output . $live_output;
  
          echo "<pre>$live_output</pre>";
  
          @ flush();
  
      }
  
  
  
      pclose($proc);           
  
  
  
  }

  And for the AJAX section i used

  function getLiveStream(){
  
  
  
  
  
          var ajax = new XMLHttpRequest();
  
            ajax.onreadystatechange = function() {
  
              if (this.readyState == 3) {
  
  
  
                document.getElementById("result").innerHTML = this.responseText;
  
              }               
  
          };          
  
          var url = 'process/getlive';
  
          ajax.open('GET', url,true);
  
          ajax.send();
  
     }

  Which sadly doesn’t work.

  The command being executed is this : 'ffmpeg.exe -i "C:/Users/BACKUP/Desktop/xampp/htdocs/testarea/test.mp4" -map 0:0 -map 0:1 -c:v libx264 -preset fast -crf 26 -c:a libmp3lame -ar 24000 -q:a 5 "C:\Users\BACKUP\Desktop\xampp\htdocs\testarea\output/test.mkv"', which i tested and it works.

  When i run the html page and the ajax script within, the ffmpeg command doesn’t even run, as i checked in task managet. It simply returns a blank text.

  When i run the php script by itself, the command runs, the file is converted but it doesn’t echo anything at all.

  After some more research i also found this page, which seems to be made for this exact purpose : https://github.com/4poc/php-live-transcode/blob/master/stream.php

  The relevant section is at the end, the code before is for dealing with options specific to ffmpeg. But it didn’t work either, with the same exact outcomes.

  Now i’m considering simply writing the output to a file and reading it from it dinamically, but i’d really like to know the reason why they both don’t work for me.

  EDIT : PHP Execute shell command asynchronously and retrieve live output answers to how to get content from a temporary file that is being written, not directly from the process.