Php Imagepng() Generating Black Image Only On Server

I am dynamically generating a waveform image from a user-uploaded sound file, using a script I've based on: http://andrewfreiday.com/2010/04/29/generating-mp3-waveforms-with-php/ T

Solution 1:

Try adding

$transparentColor = imagecolorallocatealpha($rimg, 0, 0, 0, 127);
imagefill($rimg, 0, 0, $transparentColor);

to

$rimg = imagecreatetruecolor($width, $height);
imagealphablending($rimg, false);
imagesavealpha($rimg, true);

Whole part:

$rimg = imagecreatetruecolor($width, $height);
imagealphablending($rimg, false);
imagesavealpha($rimg, true);
$transparentColor = imagecolorallocatealpha($rimg, 0, 0, 0, 127);
imagefill($rimg, 0, 0, $transparentColor);