I have an idea to develop web app where I allow users to create a playlist by uploading songs and share it. My friends can start using the playlist, like, comment and inturn share it. Similar to a facebook, pinterest but for MUSIC. <br>
But my query is that, suppose users upload songs downloaded from internet illegally is it going to affect me anyways due to copyright or licensing issues?
Do you know <a href="http://8tracks.com" rel="nofollow">http://8tracks.com</a> ? Because it sounds a lot like what you are describing. You may find the answer to your question in their Licensing page.
I've been tossing around an idea like this except having the audio sourced from YouTube as opposed to the user uploading it themselves. That avoids your ownership in hosting, but at a sacrifice in audio quality.