Animated Portable Network Graphics

import magic
# Libmagic will typically identify APNGs simply as 'image/png' due to the shared header
print(magic.from_file('animation.png', mime=True)) # Outputs 'image/png'

const fs = require('fs');
// Sniffing for the 'acTL' chunk to differentiate APNG from PNG
const buffer = fs.readFileSync('animation.png');
// In a real app, you'd parse lengths, but a quick brute-force indexOf for 'acTL' works for basic detection
const isAPNG = buffer.indexOf(Buffer.from('acTL')) > -1;
console.log('Is APNG:', isAPNG);

import "bytes"
// Go's standard library net/http will return 'image/png'.
// To detect APNG, search the initial bytes for the acTL chunk:
// isAPNG := bytes.Contains(buf[:1024], []byte("acTL"))

$mime = mime_content_type('animation.png');
echo $mime; // Standard setups will resolve this to 'image/png'. Custom binary parsing is needed to detect the acTL chunk.