Recherche avancée

Sur d’autres sites (6778)

• lavfi : fix race when func rets holder is NULL

  28 mars 2017, par Clément Bœsch

  lavfi : fix race when func rets holder is NULL
  If ret is NULL, a dummy common holder is created to hold *all* the
  
  parallel function returns, which gets written concurrently. This commit
  
  simplify the whole logic by simply not writing to that holder when not
  
  set.
  

  • [DH] libavfilter/pthread.c

• Revision 876c72a093 : AVX2 Convolve Optimization Two convolve functions were optimized for AVX2 : 1. v

  17 janvier 2014, par levytamar82

  Changed Paths :
   Modify /vp9/common/vp9_rtcd_defs.sh

  
   Modify /vp9/common/x86/vp9_asm_stubs.c

  
   Add /vp9/common/x86/vp9_subpixel_8t_intrin_avx2.c

  
   Modify /vp9/vp9_common.mk

  
  
  AVX2 Convolve Optimization

  Two convolve functions were optimized for AVX2 :
  1. vp9_filter_block1d16_h8
  2. vp9_filter_block1d16_v8
  vp9_filter_block1d16_v8 was optimized for AVX2 by reducing the number of
  loop strides by half, two strides were processed in parallel.
  vp9_filter_block1d16_v8 was also optimized in the same way also some of the
  loads were being done outside of the loop and by that preventing redundant
  loads.
  This Optimization gives 43% function level gain and 1.3% user level gain.
  Now can be compiled in Windows

  Change-Id : I2714124cfb0c14a77d7a0ce126a20db92ffbf92c

• 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 ?