Hi aiscript, for multi audio channel , I'm using audio channel select on osmf player. Audio and video are combined, not seperate file .
When I try to get information of video with ffmpeg , I see two audio map in it. If your videos like that ,it's easy to change language without refresh time , osmf can handle it. If they are seperated files, you can merge them with ffmpeg or other tools.
On the otherside , if your video does not have audio and you wanna pass it from track file , maybe a bit lag exist cause of loading and seeking the audio to the video's current time.