Gens Sound Record (GSR) is a new file format for the storage of Sega Genesis\Mega Drive music. It is more efficient than GYM in that the format stores DAC samples on an indexed table so they can be reused during the playback, avoiding redundancy and saving a lot of space. Another format, VGM, recently adopted this function as well, and since VGM is more precise than GSR, and is already more popular with a greater number of complete soundtrack sets, GSR has become somewhat obsolete.
GSR files can contain track information, as well as loops and fades. The format is being developed by Rodrigo Cardoso on his Gens+ (Gens Plus!) enhanced emulator, and so far this is the only emulator which supports the format. GSR files can be played with a Winamp plugin.