Woyzeck (1979)

Having fathered an illegitimate child with his lover, Marie, feckless soldier Franz Woyzeck takes odd jobs around his small town to provide some extra money for them. One of them is volunteering for experiments conducted by a local doctor, who puts Woyzeck on a diet of peas. This serves to drive him close to madness, and the discovery that Marie is involved in an affair with the local drum major exacerbates the situation. Pushed too far, Woyzeck resorts to violence.

Source: TMDb