PHP函数exec()无法调用ffmpeg

该问题在Drupal的flashvideo模块中出现，可能与exec的运行机制有关，直接 exec(”ffmpeg …..”)没有任何输出及结果（可能在某些情况下没问题）。
在 http://lists.mplayerhq.hu/pipermail/ffmpeg-user/2006-October/004773.html 找到答案
使用以下函数代替exec即可

1. /** change exec ($command) to **/
   2. runExternal($command, &$code);
   3.  
   4. <?php
   5. /** Adding this function to flashvideo.module*/
   6. function runExternal( $cmd, &$code ) {
   7.  
   8.    $descriptorspec = array(
   9.        0 => array("pipe", "r"),  // stdin is a pipe that the child will read from
  10.        1 => array("pipe", "w"),  // stdout is a pipe that the child will write to
  11.        2 => array("pipe", "w") // stderr is a file to write to
  12.    );
  13.  
  14.    $pipes= array();
  15.    $process = proc_open($cmd, $descriptorspec, $pipes);
  16.  
  17.    $output= "";
  18.  
  19.    if (!is_resource($process)) return false;
  20.  
  21.    #close child's input imidiately
  22.    fclose($pipes[0]);
  23.  
  24.    stream_set_blocking($pipes[1],false);
  25.    stream_set_blocking($pipes[2],false);
  26.  
  27.    $todo= array($pipes[1],$pipes[2]);
  28.  
  29.    while( true ) {
  30.        $read= array();
  31.        if( !feof($pipes[1]) ) $read[]= $pipes[1];
  32.        if( !feof($pipes[2]) ) $read[]= $pipes[2];
  33.  
  34.        if (!$read) break;
  35.  
  36.        $ready= stream_select($read, $write=NULL, $ex= NULL, 2);
  37.  
  38.        if ($ready === false) {
  39.            break; #should never happen - something died
  40.        }
  41.  
  42.        foreach ($read as $r) {
  43.            $s= fread($r,1024);
  44.            $output.= $s;
  45.        }
  46.    }
  47.  
  48.    fclose($pipes[1]);
  49.    fclose($pipes[2]);
  50.  
  51.    $code= proc_close($process);
  52.  
  53.    return $output;
  54. }
  55. ?>

原文地址  http://color-magic.cn/?p=15

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