Detecting presence of music in ambient sound I am hoping to create an application that would listen to ambient sound and detect if music is being played. It is not important to identify the music being played; just detecting that some music is being played is enough.

I looked around for existing solutions but couldn't find any. Does anyone know algorithms that I can use to solve this problem? If source code is available, all the better. I found a couple of academic papers and implemented solutions suggested in them. But the results I obtained were not satisfactory.

PS: i) It would be a bonus if the algorithm is not computationally intensive; if algorithm is completely in time-domain that would be wonderful. ii) It is okay if the solution is not very accurate; occasional false-positives are okay.
This is a tough problem. The music identification service Shazam actually has a database of acoustic fingerprints for songs. Music is composed of many variable acoustic components and there are a slew of algorithms that may be used to estimate several components. One simple example would be the zero crossing rate, which is a time domain algorithm. I would refer to this link on the subject for a brief overview of pitch detection algorithms and go from there.