AVI Audio Video Interleave

SIGNATURE = bytes.fromhex("52494646")
OFFSET = 0

def is_avi(path: str) -> bool:
    with open(path, "rb") as f:
        f.seek(OFFSET)
        head = f.read(len(SIGNATURE))
    return head == SIGNATURE

const SIGNATURE = [0x52, 0x49, 0x46, 0x46];
const OFFSET = 0;

// bytes: a Uint8Array / Buffer holding the start of the file
export function isAvi(bytes) {
  return SIGNATURE.every((byte, i) => bytes[OFFSET + i] === byte);
}

package fileid

import "bytes"

var isaviSignature = []byte{0x52, 0x49, 0x46, 0x46}

const isaviOffset = 0

func IsAvi(b []byte) bool {
	end := isaviOffset + len(isaviSignature)
	if len(b) < end {
		return false
	}
	return bytes.Equal(b[isaviOffset:end], isaviSignature)
}

const SIGNATURE: &[u8] = &[0x52, 0x49, 0x46, 0x46];
const OFFSET: usize = 0;

fn is_avi(bytes: &[u8]) -> bool {
    bytes.get(OFFSET..OFFSET + SIGNATURE.len()) == Some(SIGNATURE)
}

<?php
$signature = "\x52\x49\x46\x46";
$offset = 0;

function is_avi(string $bytes): bool {
    global $signature, $offset;
    return substr($bytes, $offset, strlen($signature)) === $signature;
}