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• FFmpeg : encoding in webm (vp9) for windows

  2 juillet 2015, par Seltymar

  I’m trying to encode jpegs to a webm video in vp9 on windows 7.

  I followed the instructions from webmproject in 2 pass.
  I changed \dev\nul by NUL.

  ffmpeg.exe -i %4d.jpg -c:v libvpx-vp9 -pass 1 -b:v 1000K -threads 8 -speed 4 -tile-columns 6 -frame-parallel 1 -auto-alt-ref 1 -lag-in-frames 25 -an -f webm NUL
  
  
  
  ffmpeg.exe -i %4d.jpg  -c:v libvpx-vp9 -pass 2 -b:v 1000K -threads 8 -speed 1 -tile-columns 6 -frame-parallel 1 -auto-alt-ref 1 -lag-in-frames 25 -c:a libopus -b:a 64k -f webm out.webm

  but after the first pass, it tells me "output file is empty, nothing was encoded". But the second pass create the video.

  I also tryed in one pass :

  ffmpeg -i %4d.jpg -c:v libvpx-vp9 -crf 10 -b:v 0 output.webm

  Then I want to use the output video using html5 video and canvas tags as below.

      
  
  
  
  
  
  
  
  
  
  <canvas>
  
          Your browser does not support the canvas tag.
  
  </canvas> 
  
  <code class="echappe-js">&lt;script&gt;<br />
  
  <br />
  
  <br />
  
          var videos = document.createElement('video');<br />
  
          videos.src = &quot;output.webm&quot;;<br />
  
          videos.type = &quot;video/webm&quot;;<br />
  
          videos.load(); <br />
  
          videos.play();<br />
  
          videos.playbackRate = 1;<br />
  
          var videoImage0 = document.getElementById('canvas');        <br />
  
          videoImage0.width = 2700;<br />
  
          videoImage0.height = 1350;<br />
  
  <br />
  
          var videoImageContexts =videoImage0.getContext('2d');<br />
  
          //// background color if no video present<br />
  
          videoImageContexts.fillStyle = '#0000ff';<br />
  
          videoImageContexts.fillRect(0, 0, videoImage0.width, videoImage0.height);       <br />
  
          animate();<br />
  
  <br />
  
      function animate() {<br />
  
          requestAnimationFrame(animate);<br />
  
          update();<br />
  
  <br />
  
      }<br />
  
  <br />
  
      function update() {<br />
  
  <br />
  
          if (videos.readyState === videos.HAVE_ENOUGH_DATA) {<br />
  
              videoImageContexts.drawImage(videos, 0, 0);<br />
  
          }<br />
  
      }<br />
  
  &lt;/script&gt;
  

  result :

  1. With both methods the output video can’t be read in VLC but it can be read if I drag and drop in firefox or chrome or using the video tag only.
  2. The html page above works correctly on chrome but not in firefox. In firefox, the color is not correct like if the blue channel was translated.
     

  I think the problem is the encoding with FFmpeg. I’m using the static build from zeranoe. Here is the version

  and libvpx is enable.

  My questions :

  • Is there a problem on my command line ?

  • Is there a problem in my JS code that could lead to error in the decoding process ?

• How can I manually pass a SoundCloud track duration to HTML5 audio ?

  30 janvier 2016, par thebaer

  I’m currently using a stripped-down version of Canvas.fm to convert SoundCloud mp3 streams into ogg streams using Node and ffmpeg, to support the audio element in ogg-playing browsers like Firefox. My problem is : while the duration is correctly set for SoundCloud’s mp3 streams, the ogg stream gives an indefinite duration in the player ; I want the actual duration to show up.

  I noticed when requesting a SoundCloud mp3 stream, I get a canceled request, a pending one, and then a 206 Partial Content response. My Node app does similar redirects, without as many headers, since I’m sending them myself.

  Should I be trying to calculate/forge the Content-Length or Content-Range headers ? Or does HTML5 audio get the duration from mp3 metadata/ID3 information ? If I can get the duration from SoundCloud’s API (which I can), how can I pass this to the client in my ogg stream ?

• How can I manually pass a SoundCloud track duration to HTML5 audio ?

  19 juin 2013, par thebaer

  I'm currently using a stripped-down version of Canvas.fm to convert SoundCloud mp3 streams into ogg streams using Node and ffmpeg, to support the audio element in ogg-playing browsers like Firefox. My problem is : while the duration is correctly set for SoundCloud's mp3 streams, the ogg stream gives an indefinite duration in the player ; I want the actual duration to show up.

  I noticed when requesting a SoundCloud mp3 stream, I get a canceled request, a pending one, and then a 206 Partial Content response. My Node app does similar redirects, without as many headers, since I'm sending them myself.

  Should I be trying to calculate/forge the Content-Length or Content-Range headers ? Or does HTML5 audio get the duration from mp3 metadata/ID3 information ? If I can get the duration from SoundCloud's API (which I can), how can I pass this to the client in my ogg stream ?