Fix 403 forbidden error

[BrunoMoreira99]

Fixes #417.

This error has been happening to me way too frequently, after I saw #417 (comment) from @omarroth I was able to fix this issue. So, thanks 👍 I wouldn't have had a clue how to fix this otherwise.

I tested this thoroughly and was able to confirm that this does indeed fix the 403 forbidden error.

I went ahead and added some comments also, please tell me if you'd prefer no comments.
There is a much more detailed explanation of the issue at ytdl-org/youtube-dl#18927.

[BrunoMoreira99]

On a side note, I don't think this function is actually doing anything right now.

node-ytdl-core/lib/info.js

Lines 246 to 250 in 43c045e

	const decipherURL = (url, tokens) => {
	return url.replace(/\/s\/([a-fA-F0-9.]+)/, (_, s) => {
	return '/signature/' + sig.decipher(tokens, s);
	});
	};

I tackled around that function a bit because I thought I'd need to change it as well, but I came to the conclusion that actually the URLs it is meant to decipher (which I assume are only those from livestreams, usually) don't actually have the signature after s but after sig or signature, and I think that signature is already deciphered (as I tried to decipher it but THEN it would throw a 403 error), in fact, I tried not using this function at all and just passing the url directly to getDashManifest and getM3U8 and it worked, although the livestream actually only plays for a few seconds, but I believe that is a whole different issue.

[TheAkio]

The issue with the stream stopping after a few seconds might be related to YouTube having a very weird way of doing MPEG-TS Livestreams. I made a small library that basically deals with that stuff before piping it to FFMPEG but it is also broken right now. I wanted to check over the next few days what's causing the issue. Might just be some small changes since I made that library. You can check it out here: https://github.com/TheAkio/ytls

I'm not actively working on that library and I don't plan to, so if you wanted we could build that handling into ytdl-core directly.

EDIT: ytls is actually not the issue. It was us not passing the correct format to it because YouTube probably added some new ones and our filter logic failed.

[fent]

Thank you for this.

Still in the middle of fixing tests, but merging this in and releasing a patch version.