String Quartet no. 5  is composed by the danish composer Rued Langgaard. Here played by Kontra Kvartetten:

Peter Fabricius – Bratsch
Anton Kontra – Violin
Boris Samsing – Violin
Morten Zeuthen – Cello

Rued Langgaard (born Rud Immanuel Langgaard; 28 July 1893 – 10 July 1952) was a late-Romantic Danish composer and organist. His then-unconventional music was at odds with that of his Danish contemporaries and was recognized only 16 years after his death. [source]

The danish filmproducer Peter Aalbaek who normally work together with Lars Von Trier is planning to make a feature movie about Rued Langgaard. Aalbaek has been fascinated by Langgaards history throughout his career, and his graduation film from the Film School also portrayed the composer.

https://www.youtube.com/watch?v=rr7Pvu_2ew4

picture from the homepage of Rued Langgaard Selskabet: