The famous Strasbourg codex CZ-Pu XI.E.9 (see DIAMM source description), which contains a number of ars nova pieces and German tenor-songs, features on the top line of fol. 248v a nameless fragment of mensural notation. It sounds very familiar to me and everyone I’ve asked thought the same—but no one so far could quite put the finger on it. Therefore my question is: Who knows this bit of cantus and can attach it to a composition? My guess is that it is a piece of a cantus line of a three voice ars nova or ars subtilior composition:
PS: The puzzle is already solved! Julien Taurand found the fragment to be the beginning of the ballade “Sans joie avoir” from Codex Chantilly. See next blog for a transcription.