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• ffmpeg AVPixelFormat and manager C++ System::Drawing::Imaging::PixelFormat conflict

  29 novembre 2016, par H S T

  There is #define PixelFormat AVPixelFormat inffmpeg. You can not use System::Drawing::Imaging::PixelFormat in a header file containing this. How can I usePixelFormat in C # ?

  .h

  using namespace System::Drawing::Imaging;
  
  public ref class CTest{
  
      static Imaging::PixelFormat Format24bppRGB = Imaging::PixelFormat::Format24bppRgb
  
  };

  .cpp

  #include"ffmpeg head file"
  
  ...

• 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 ?

• ffmpeg splitting video into hls slice, why hls_time option is not working ?

  6 juillet 2019, par workplaylifecycle

  macbook:output developer$ ffmpeg -i ../output.mp4 -f hls -hls_time 1 -hls_list_size 1000000 index.m3u8
  
  macbook:output developer$ 
  
  macbook:output developer$ head index.m3u8 
  
  #EXTM3U
  
  #EXT-X-VERSION:3
  
  #EXT-X-TARGETDURATION:8
  
  #EXT-X-MEDIA-SEQUENCE:0
  
  #EXTINF:3.136467,
  
  index0.ts
  
  #EXTINF:8.341667,
  
  index1.ts
  
  #EXTINF:8.341667,
  
  index2.ts
  
  macbook:output developer$

  I want video slice with length around 1 second, but all I got TARGETDURATION: 8 have you noticed that, where does it come from ? I have not set anything like 8, confusing... thanks