how to add new audio channels to mp4 which already have audio channels

[ggslayer]

Hi, I want to mix a new audio channels(backgound music) to mp4 file which already have two audio channels, I think this refer to how to mix the existing and new audio channels, I have no idea how to accomplish this purpose, can you give me some advise? thank you! If there is some example code, that's perfect! thank you ~~

[saudet]

You could use a filter: https://ffmpeg.org/ffmpeg-filters.html

[ggslayer]

Hi, I don't want to use ffmpeg cmd method to archive this, In my situation , I must frame by frame to done this, (there is a lot of code already writen), I want to use ffmpegframegrabber / recoder /frame's direction, And do some sample data operate to archive this, can you give me some help about this direction? or use FFmpegFrameFilter? Is there some example about my audio mix purpose?

[saudet]

Again, there are a couple of examples of FFmpegFrameFilter in the samples, but we can use any other filter command: https://github.com/bytedeco/javacv/tree/master/samples

[ggslayer]

ok I'll try it, thank you