Leveler

Leveler is a free app for Mac, iPhone and iPad that automatically levels the audio in videos and audio recordings, so that speech stays at a consistent loudness. It works by analyzing the whole file, applying a slow look-ahead gain curve that only acts on speech, and applying a true-peak limiter before writing a new leveled copy. The video stream is copied without re-encoding, and only the audio track is replaced. Users can choose loudness targets, including a default of -16 LUFS with a -1 dBTP true-peak ceiling and presets for YouTube and broadcast. Supported inputs include MP4, M4V and MOV video, and WAV, AIFF, M4A and MP3 audio. A watched-folder option levels new files automatically as they arrive. The app is aimed at people who produce spoken-word content such as podcasts, videos and recordings that have uneven speech levels between speakers.