Contrary to what people might reasonably expect, music in the camps (and ghettos) is a huge topic that has been covered in quite a number of books and articles, ranging from memoirs by camp musicians to academic monographs. There is even a dedicated website, run by double-degreed musicologist and historian Shirl Gilbert.

You asked specifically about the music played at roll call, presumably at Auschwitz, as the Auschwitz orchestras (there were at least half a dozen operating simultaneously at one point, including the only female camp orchestra, led for quite a while by Alma Rosé, Gustav Mahler's niece) are the best known. But there is so much more to say on this subject that you will forgive me if I take it from the beginning.

The first concentration camps were established in 1933, mainly to house political opponents to the Nazi regime, and some had music played by inmates right from the start. In fact, it quickly became the done thing among some camp commanders who tried to have a better ensemble than the next guy. Nevertheless, those first few years camps differed wildly in scope and organisation, until the whole system was taken over by the SS in 1936. They would run all concentration camps (KZ) and extermination camps until the end of the war and established the rules we are now familiar with, the roll calls, the barracks with the Kapo inmate overseers, the different coloured badges for the various categories of inmates, etc. And the camp orchestras.

The size of the ensembles varied from an entire symphony orchestra at Auschwitz I (the original main camp) where the SS could draw from an enormous pool of candidates (1.3 million people were sent there), to from between three and ten members at Treblinka, which was an extermination camp exclusively and housed only a few hundred inmates (slave workers) at any one time.

Musical selection was obviously not the prerogative of the inmates. They were told what to play and when to play it. The occasions that the SS deemed suitable were many and varied. There were regular open-air concerts in the summer, sometimes attended by the SS only, but at other times the prisoners were allowed in the audience as well. Other "happy" occasions were Nazi holidays and visits by prominent people, or just whenever the SS felt like it. At these times a wide range of music was played, from serious classical music by mainly German composers to lighter offerings, popular songs, movie songs, operetta, etc.

Other occasions were more unpleasant and downright sinister. Music was played at executions and punishments. The orchestras played at the start and end of the working day when work crews left and re-entered the camp, mostly marching music and up tempo popular German songs were deemed suitable for these occasions. An example specifically mentioned in Szymon Laks' Auschwitz memoir is "Berliner Luft". In Auschwitz II-Birkenau occasionally during the selection of incoming trains, when it was decided who would be gassed immediately and who sent to work, musicians played upbeat folk songs to reassure the arrivals.

Roll call, the counting of prisoners, could feature more serious music, such as on one occasion at Auschwitz the Leonore overture from Beethoven’s Fidelio, or Viennese waltzes in Buchenwald.

Another infamous feature of camp life was the enforced singing by inmates marching to and from work as well as during work at times. The songs varied from German folk songs such as Szymon Srebrnik had to sing for the SS at Chelmno extermination camp when he was 13 years old (from Claude Lanzmann's masterly documentary Shoah), to antisemitic Nazi songs like the Horst Wessel Lied, to various specially composed camp songs as the Buchenwaldlied which was always sung at roll call and the Treblinkalied (sung here by SS man Franz Suchomel in Claude Lanzmann's Shoah).