This Artist is the official "Mehter Band" of the Military Museum ("Askerî Müze ve Kültür Sitesi Komutanlığı") of Instanbul, Turkey. It is the current official representative of a centuries-long Ottoman military band] tradition. It is sometimes known as the "Janissary band", because historically many members of such bands were Janissary soldiers.
It's not clear exactly what the official name of this group is in Turkish. I do not read Turkish, so it's hard sorting out reference to Mehter music groups in general from references to this official group organised by the Turkish government.