Where can I change the HEX code of a multimedia file so that it stops opening after that?

Question

Python

Encrypting large files takes a lot of time. Is it possible to slightly change ( I mean add a couple of characters or XOR a piece without bothering too much with permutations like in encryption ) the HEX code of a multimedia file ( video, music ) so that it stops opening after that? If yes, where?
PS Just then, having a small script with you, it will be possible to "protect" the file in a few seconds.

Answer 1

Because what kind of file and what format it does not say, then the answer is simple - change something in the header.
And so - you need to look at what kind of file format, and proceed from its structure.
In general, it’s quite generalized in theory - you can add symbols to the beginning. Or even cooler - invert the entire file.

Answer 2

1. in Windows, you can stupidly change the extension * .mp3 -> * .mpthree
   although files like wav, even with a corrupted signature, will be played.

Answer 3

Almost all files store metadata at the very beginning. Therefore, encrypt the first kilobyte - more than enough for almost any type of file.
Players that check the validity of files will not open this one.