Rock in a radio directory is really five formats wearing one label, and the station tags rarely tell you which one you have found. Classic rock plays a canon that hardened around 1990 and has barely moved since. Hard rock keeps the volume but drops the ballads. Alternative descends from the nineties college-radio format and carries most of what is actually new. Indie overlaps with alternative but leans smaller and more recent. And metal, which usually gets its own tag, splits again into a dozen subgenres that do not mix comfortably.
Rock is also the genre where stream quality matters most, and the reason is technical rather than snobbery. A dense guitar mix with cymbals riding over the top is close to the worst case for a low-bitrate encoder: cymbals are noise-like, they eat bits, and when the encoder runs out it throws away the high end first. That is why a 96 kbps MP3 rock stream sounds washed out and swimmy while a 96 kbps talk stream sounds fine. If a rock station here is running 192 kbps, that number is doing real work.
The other thing worth knowing is that rock radio is where local stations are most distinct from one another. Chart pop converges internationally; rock does not. German rock radio, Italian rock radio and American classic rock stations play overlapping but noticeably different canons, and the regional stations in this directory are a quicker way to hear that than any playlist.
