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• A nice comparison of mics

  3 juin 2010

  DVEStore has done a great comparison of different types of microphones on video. Audio is a black art, and folks rarely put in the time to do A/B/C comparisons. We tend to just default to a set of mics that we’ve decided are "good enough" and then don’t go back to reevaluate.

• FFmpeg - Rotating at angle

  23 septembre 2017, par connor

  I’ve been working through FFmpeg, but I have been unable to get a rotation to run from the examples they have on their site. I am trying to "wiggle" a video back and forth at a fixed point on the bottom - think a head moving left to right (and so on).

  I am attempting to do this with the filter "rotate" (https://ffmpeg.org/ffmpeg-filters.html#rotate). Attempting to use their examples, I get an error.

  This is what I have so far :

  ffmpeg -i vid1.mp4 -i vid2.mov -loop 1 -i image.png -filter_complex "\
  
      [2:v]alphaextract, scale=240x160[mask];\
  
      [0:v] scale=240x160, rotate=A*sin(2*PI/T*t) [ascaled];\
  
      [ascaled][mask]alphamerge[masked];\
  
      [1:v]scale=480x360[background];\
  
      [background][masked]overlay=120:20"\
  
      -c:a copy 65B6354F61B4AF02_HD_sq.MOV

  I am using "rotate" directly from an example in an attempt to get something to run at all.

  The error I get back is :

  [Parsed_rotate_3 @ 0x7ff4476045e0] [Eval @ 0x7fff5b3e3f00] Undefined constant or missing '(' in 'T*t)'
  
  [Parsed_rotate_3 @ 0x7ff4476045e0] Error occurred parsing angle expression 'A*sin(2*PI/T*t)'
  
  [Parsed_rotate_3 @ 0x7ff4476045e0] Failed to configure output pad on Parsed_rotate_3
  
  Error reinitializing filters!
  
  Failed to inject frame into filter network: Invalid argument
  
  Error while processing the decoded data for stream #1:0

  If I remove ’A’, ’T’, ’sin’, etc, rotate does actually work, but far from the desired behavior.

  Am I missing something to expose those params ?

• Converting video with ffmpeg from a script not in the root folder

  30 octobre 2017, par Daniel Ormerod

  I am using ffmpeg to convert videos, create thumbnails etc.

  I made the below function to convert a video and when I run it in a script in the root folder it converts ok.

  However, I am using ajax to upload the video and the script is located /ajax/upload-video.php and when I run it in that folder it fails to convert.

  I have tried sending the $src and $dest up with ../ before the filenames to go back a folder but it isn’t working.

  Can anybody help ?

  Do I need to add something to the $command line to tell it to go back a folder ?

  These are the variables being used in the function :

  $ffmpegpath = 'ffmpeg.exe';
  
  $src = 'videos/video1.wmv';
  
  $dest = 'videos/video1.mp4';

  I have tried :

  $ffmpegpath = 'ffmpeg.exe';
  
  $src = '../videos/video1.wmv';
  
  $dest = '../videos/video1.mp4';

  And the function :

  function convert_video($src, $dest) {
  
  
  
      global $ffmpegpath;
  
  
  
      if (!file_exists($src)) {
  
  
  
          echo '<p>The file does not exist</p>';
  
  
  
      } else {
  
  
  
          $command = "$ffmpegpath -i $src $dest";
  
  
  
          @exec($command, $ret);
  
  
  
          if (!file_exists($dest)) {
  
  
  
              echo '<p>The file failed to create</p>';
  
  
  
          } else {
  
  
  
              if (filesize($dest)==0) {
  
  
  
                  echo '<p>The file created but has not filesize</p>';
  
  
  
              } else {
  
  
  
                  echo '<p>File Created Successfully</p>';
  
  
  
              }
  
  
  
          }
  
  
  
      }
  
  
  
  }