To answer the question :
ffmpeg -i movie.mp4 -i english_track.ac3 -c:v copy -c:a aac -map 0:v:0 -map 1:a:0 -async 1 -shortest output_synced.mp4 Where To Download English Audio Track For Movies
Finding a standalone English audio track for a movie can be challenging because audio tracks are generally protected by the same copyright laws as the film itself. However, there are several legal methods to find, extract, or sync English audio. To answer the question : ffmpeg -i movie
While there isn't a single "standard" database for standalone audio files, here are the most common ways to find them: Where To Download English Audio Track For Movies