效果图：

参考：

http://php.net/manual/zh/function.pack.php

https://www.jianshu.com/p/947528f3dff8

http://blog.csdn.net/midfar/article/details/7227758

function wav_graph($file)

{

if(!is_file($file)) return false;

$fp=fopen($file, 'r');

$size=36;

$offset=0;

$raw=fread($fp, $size);

$header=unpack('A4Riff/VSize/A4Type/A4Head/VHeadSize/vAudioFormat/vNumChannels/VSampleRate/VByteRate/vBlockAlign/vBitsPerSample', $raw);

$offset+=$size;

fseek($fp, $offset);

while(true){

$size=8;

$raw=fread($fp, 8);

$chunk=unpack('A4ID/VSize', $raw);

if($chunk['ID']==='data') break;

$offset+=($size+$chunk['Size']);

fseek($fp, $offset);

}

$samples=$chunk['Size']/$header['BlockAlign'];//wave length = samples

$px_per_second=100;//px

$second_per_sample=1/$header['SampleRate'];//s

$time=$samples*$second_per_sample;//time of media

$width=$px_per_second*$time;

$samples_per_px=$header['SampleRate']/$px_per_second;//

$amplitude=pow(2,intval($header['BitsPerSample'])-1);//2^16 max amplitude

$height=400;//px height of one channel

$px_per_amp=$height/$amplitude;//px per amplitude

//var_dump($width);var_dump($height);exit;

$im=imagecreate($width, $height*$header['NumChannels']);//two channels

$bg_color=imagecolorallocate($im, 255, 255, 255);

$line_color=imagecolorallocate($im, 255, 0, 0);

$offset+=8;

fseek($fp, $offset);

$x=0;

$y1=[];//start y

$y2=[];//end y

for($i=0;$i

$y1[$i]=$height*$i+($height/2);//start height of per channel

}

while (true) {

$raw=fread($fp, $header['BlockAlign']*$samples_per_px);// read n samples in 1 px

if($raw==false) break;

$len=strlen($raw);//bytes

$sample=unpack('s*', $raw);

$y_sum=[];

for($i=0;$i

$y_sum[$i]=0;

}

foreach ($sample as $key=>$value) {

$channel=($key+1)%intval($header['NumChannels']);//0 or 1

$y_sum[$channel]+=$value;

}

foreach ($y_sum as $channel=>$value) {

$y_ave=$value/($len/$header['BlockAlign']);//average of y

$y2[$channel]=$y_ave*$px_per_amp+$height*$channel+($height/2);

imageline($im,$x,$y1[$channel],$x+1,$y2[$channel],$line_color);

$y1[$channel]=$y2[$channel];

}

$x++;

}

fclose($fp);

header("Content-type:image/png");

imagepng($im);

imagedestroy($im);

}

wav_graph('test.wav');