The band played on

A new doco examines the horrors of Auschwitz through music.

- RICHARD BETTS

As the musicians play, the tune is instantly recognisable: Mozart's Eine Kleine Nachtmusik. It's not quite as you know it, though.

The orchestra is small, and there are odd instruments - recorder, accordion - that Mozart would not have used.

The familiar alien music is how it was arranged and performed in Auschwitz-Birkenau concentration camp. More than 1.1 million people died there, and for many it would have been the last music they heard - the gas chambers were near where one of the camp's orchestras performed each day.

This music was not for entertainment; it was weaponised, a point English composer-conductor Leo Geyer makes early on in The Lost Music of Auschwitz, a documentary produced to mark this year's 80th anniversary of the camp's liberation.