The original composer still owns the copyright for the composition but you own the copyright for the performance. Just like if you sang someone else's song.
Much like cleanroom-written code, these are often made without ever looking at the official sheet music, just hearing some synth midi and figuring out a neat way to replicate the general idea using traditional instruments.
But yes, apparently it would be violating US copyright law to rearrange music this way.
Comments
The original composer still owns the copyright for the composition but you own the copyright for the performance. Just like if you sang someone else's song.
Much like cleanroom-written code, these are often made without ever looking at the official sheet music, just hearing some synth midi and figuring out a neat way to replicate the general idea using traditional instruments.
But yes, apparently it would be violating US copyright law to rearrange music this way.
http://ostrowesq.com/no-you-dont-own-your-arrangement-of-tha...