I'm wondering what can prevent the Quicktime player from playing the audio track alongside a video.
The files I have are MPEG-4. When it is launched on macOS QuickTime, there is no sound. I've tested it quickly on an iPhone, and audio is played when the same files are launched. Elmedia Player also successfully produces sound on the same computer.
How can I fix the problem that prevents QuickTime from playing the audio track?