Looking for old movie about rock music

I barely remember about this movie since it was long time ago.
This movie is about some rock bands, and there’s a kind of 80’s vibes.

I only remember the most impressive introduction and ending.

At the first time, a boy is sitting in terrace and playing some guitar phrase.
Then someone plays the answer of that phrase from somewhere in his town.
They even don’t know each other, but anyway they communicate each other through the guitar play sometimes.

In the end, same composition.
A boy play some guitar, and the other answers that.
They repeat that several times.
Eventually their play is getting more complicate, and musical.

Then movie ends.

In the ending scroll, brief explaination about movie characters goes on.

I know it’s too abstract, but hopefully I could find this movie.