Extra custom parameter for audio track

[alpha-0]

Since doing default pass-through of any Atmos audio track to MP4 container would result a broken Atmos audio track (no atmos), extra ffmpeg parameters "-c copy -strict -2" are needed for these tracks to output correctly.

I am a mac user who always encoding video to mp4 container. Atmos audio is very common nowadays and it's quite inconvenient for me to make a mp4 file with proper Atmos. I need to use Subler.app to mux the original Atmos audio track back to the mp4 video after the encoding task with Fastflix.

I know this is an issue of mp4 container but I wish Fastflix could provide an extra/custom parameter for audio track even in case of no conversion. I think no gui support is also ok, manual editing the extra parameter on a line of the text config file is at least an easy viable feature.

Maybe it's time to have some progress for the [Feature Request] Offer deeper audio encoder options.