[PHP] advanced tutorial: convert a WAV file into an image file and display it on the page

Requirement: convert a WAV file to a PNG file and display it.

Wav_to_png.php:

<?Phpfunction 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 minuteheader("Content-type: image/png");$im = imagecreate($s / $w, $h * $c * 2);imagecolorallocate($im, 0xff, 0xff, 0xff); // white bg$color = imagecolorallocate($im, 0, 0, 255); // blackimagestring($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');?>

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