Aff-Wild2 is a large-scale in-the-wild database and an extension of the Aff-Wild dataset for affect recognition. It approximately doubles the number of included video frames and the number of subjects; thus, improving the variability of the included behaviors and of the involved persons. It is the only existing in-the-wild database with annotations for all 3 main behaviour tasks.

The Aff-Wild2 is annotated in a per frame basis for the seven basic expressions (i.e., happiness, surprise, anger, disgust, fear, sadness and the neutral state), twelve action units (AUs 1,2,4,6,7,10,12,15,23,24,25, 26) and valence and arousal. In total Aff-Wild2 consists of 564 videos of around 2.8M frames with 554 subjects. Aff-Wild2 displays a big diversity in terms of subjects' ages, ethnicities and nationalities; it has also great variations and diversities of environments.

Sources: 1) Expression, affect, action unit recognition: Aff-wild2, multi-task learning and arcface; 2) The 6th affective behavior analysis in-the-wild (abaw) competition