php实现将wav文件转换成图像文件并在页面中显示的方法

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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');

?>