The great paradigm shift in the written transmission of polyphonic music in the early modern era remains the "revolution of the printing press": the invention of printing from movable type pioneered by Ottaviano Petrucci in 1501. The context of the institutional music book is usually that of the chapel, which increasingly implied an ensemble of singers charged with the performance of polyphony, and the sacred ritual. The repertory is consequently associated with the local liturgy. The main focus in German-speaking lands is on the Trent codices, containing about 1,300 pieces, by far the richest source of polyphonic music from the period. The largest category of songbooks is French chansonniers. Like the poetry on which they are based, chansonniers are widespread not only in France and the Low Countries, but across Europe, particularly in Italy. The most important source of polyphonic presentation codices was the workshop of Petrus Alamire at the Habsburg-Burgundian court of Margaret of Austria.