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<?php

 function wav_graph($file, $f=0, $w=0)

 {

  global $DATA_DIR;

  if(!is_file($file))

   return 0;

  $fp = fopen($DATA_DIR.$file, 'r');

  $raw = fread($fp, 36);

  $str = '';

  $header = unpack('A4Riff/VSize/A4Wav/A4Head/VHeadSize/vPCM/vChannels/VSampleRate/VByteRate/vBlockAlign/vSampleBits', $raw);

  foreach($header as $k=>$v)

   $str .= $k.': '. $v.' ';

  fseek($fp, 36 + $header['HeadSize'] - 16);

  $raw = fread($fp, 8);

  $data = unpack('A4Data/VDataSize', $raw);

  foreach($data as $k=>$v)

   $str .= $k.': '. $v.' ';

  $b = $header['SampleBits'];

  $c = $header['Channels'];

  $l = $b * $c / 8; // sample frame length in bytes

  $s = $data['DataSize'] / $l; // total number of samples

  $r = $header['SampleRate'];

  if($f)

   $h = pow(2, $b) / $f;

  else

   { $h = 200; $f = pow(2, $b - 1) / $h; }

  if($w == 0)

   $w = round($r / 1000); // default to show 1k sample frames per minute

  header("Content-type: image/png");

  $im = imagecreate($s / $w, $h * $c * 2);

  imagecolorallocate($im, 0xff, 0xff, 0xff); // white bg

  $color = imagecolorallocate($im, 0, 0, 255); // black

  imagestring($im, 5, 5, 5, $str, $color);

  $x=0; $y = array(); $yn = array();

  for($i = 0; $i < $c; $i++) $y[$i] = $h * $i + $h;

  $n = $l * $w;

  while(1)

  {

   if($s == 0)

    break;

   if($s < $n)

    $n = $s;

   $samples = fread($fp, 1000 * $n);

   if($samples === FALSE)

    break;

   $packed = unpack("s*", $samples);

   foreach($packed as $k=>$v)

   {

    $cnt = ($k-1) % ($w * $l) ;

    if( $cnt > $c - 1)

     continue;

    $yn[$cnt] = $h * $cnt + $h - $v / $f;

    imageline($im, $x, $y[$cnt], $x+1, $yn[$cnt], $color);

    $y[$cnt] = $yn[$cnt];

    $x++;

   }

   $s -= $n;

  }

  imagepng($im);

  imagedestroy($im);

 }

 wav_graph('GetWave.wav');

?>