YouTube search filters

Hi! I wanted to provide some information on how YouTube's search filters work, as I noticed currently NewPipe uses hardcoded values. Sorry if this is the wrong place for this.

The &sp= parameter is a Base64'd protocol buffer that contains all the filters. I'd recommend looking here for a working implementation. It's pretty short, but essentially you have (about) two bytes for each filter, one (or more) bytes as a type, and then the other byte as a value, for example:

date month
0x08 0x04

Features (live, HD, ...) have a value of 1:

HD   true
0x20 0x01

HDR       true
0xc8 0x01 0x01

Once you've added all your filters, give it a header (which contains the only mandatory filter, sort, see the code above for details), Base64 encode, URI escape, and you're good to go.

Hopefully this is useful, and I want to thank the NewPipe team for providing their excellent work for others.

Start by locating NewPipeExtractor's current hardcoded YouTube search-filter handling, then compare it with the linked Invidious implementation. Trace how the sp parameter is assembled, including its sort header and Base64/URI encoding, and verify that the documented date and feature filter examples produce usable search URLs.