The MMI Facial Expression Database is a popular facial expression dataset involved by Maja Pantic, Michel F. Valstar accessable here.

The database consists of over 2900 videos and high-resolution still images of 75 subjects. It is fully annotated for the presence of AUs in videos (event coding), and partially coded on frame-level, indicating for each frame whether an AU is in either the neutral, onset, apex or offset phase. A small part was annotated for audio-visual laughters. The database is freely available to the scientific community.