Is it possible for a musician to publish their music in a way so that everybody else can do with it whatever they like?
Yes. This happens all the time, and sometimes sounds come from places like BBC.
If so, are there already websites that deal with only this type of music? Like there is pexels.com for images?
Yes and no. People put up websites and other things that let you download music, but most of it isn't as organized as the free stuff for artists. It also seems like it is more decentralized and requires a bit more work, sometimes hours of work. It is quicker to look at photos than it is to listen to music and sound clips.
Sources: Spouse creates somewhat experimental electronic music, and uses free-to-use sounds alongside his own stuff. I've watched him sit for hours sorting through sounds and clips and music. Also, youtubers often use such music and link to it in their descriptions (Steve the Bartender, for example, and Im pretty sure Binging with Babish does something similar, or at least did at one time).
Well, like in open source software we have licenses like MIT and WTFPL, in creative industries there's different Creative Commons licenses like CC0 or CC-BY-SA for example which would grant different usage rights in certain circumstances.
There's a lot of different mediums which supports sharing and searching for media under different CC licenses, I've tagged a majority of my SoundCloud releases for example with great success.
If we're talking about a whole site dedicated for openly licensed music and audio, freesounds.org comes to mind.
The issue with the permissive licensing is when the works get legally used in works that aren’t licensed that way. This is a common cause of YouTube contentID legal “false positive” results.
Both you and the other person have the rights to that audio and platforms like YouTube have put no effort into giving us a solution to resolve this “edge case”.
Splice is literally a sample shop, instead of buying from a certain company's web shop and paying for a whole sample pack at once, you can cherry pick sounds and just pay for what you need and mix and match several packs and company offerings at once.
They're under rather strict licensing terms though, no reselling as samples even if they're heavily modified for example.
Glad to see a few people have brought up Jamendo already, but I'm really surprised that no one has mentioned ccMixter [0]. This is one of the really early sites to try and address this exact need. They have an enormous back catalog of open-licensed music designed specifically for mixing and reuse, and a still quite active community of dedicated users (though the site design needs a bit of a refresh).
I'm currently looking into this for streaming (twitch in particular) specifically.
A musician can license their music within the Creative Commons. This means that people can do almost whatever they want, use it wherever, remix it, etc... As long as the author gets attribution.
Similarly, specifically for streaming, you would need a _synchronization license_, the license required to synchronize music to image (ie, streams).
It is possible to issue a global blanket sync license, meaning that basically everyone can use it, usually with the same requirement that you the streamer give attribution
Nine Inch Nails released the album "Ghosts I - IV" under the Creative Commons license (BY-NC-SA) and the banjo riff in the song "Old Town Road" by Lil Nas X was sampled from a song on this album.
If so, are there already websites that deal with only this type of music? Like there is pexels.com for images?