Baude Cordier (c. 1370/1380, Reims, France - before 1440) may have been the nom de plume of Baude Fresnel.
Cordier's works are considered among the prime examples of ars subtilior, in his case using red note notation (coloration) to adjust the rhythm of a particular note from its usual form -- a form of mensural notation.
Ten of Cordier's secular pieces survive, most rondeaux, and some are rhythmically complex late 1300's / early 1400's spins on the above, such as Amans amés secretement (Lovers, love discretely)
and the slightly simpler Belle, Bonne, Sage (Beautiful, Good, Wise, the heart-shaped eye-music, with even a miniature heart of three red notes in upper left), with greater emphasis on lyrical melody (both are rondeau examples transcribed in HAM).
Belle, Bonne, Sage is given as one of two Cordier chansons in the Chantilly Manuscript. The other is another bit of eye music, the circular canon Tout par compas suy composés (With a compass was I composed).
[8380 Dunstable / 8370 Baude Cordier / 8370 Ciconia]