HeyGen: Avatar IV is an image-to-video model that animates a single photo into an expressive, lip-synced talking-head video. Rather than only matching mouth shapes to words, it interprets the vocal tone, rhythm, and emotion of the audio to drive head motion, facial expression, and gestures, producing output at up to 1080p. The spoken audio comes from one of two inputs: a text script, which the model voices with HeyGen text-to-speech, or a supplied audio track, which the image is lip-synced to directly. Passthrough parameters let you choose a voice, tune voice settings, set expressiveness, prompt specific motion, replace or remove the background, add captions, and title the video.