[FFmpeg-user] Copy input audio in file to two tracks in output audio file

[Christian]

Hi list,

my goal is to create MP4 container with two audio tracks and one video
track. The video and one audio should just be copied. Additionally the
new MP4 should have another audio track which is the same as the first
audio track but encoded via other codec.

So I have original.MKV with h264 and AC3(5.1) inside.

The new movie should become new.MP4 with h264, AC3(5.1) and AAC(2.0) inside.

Needing that for having a AAC-"fallback"-track inside: if device can't
play AC3 (like iDevices) they can fallback to AAC (this seems to be
supported).

Can anyone help me with this? I'am totally clueless how to accomplish
this - seems that the documentation is just too hardcore for me.

PS: Hope my question was clear enough... :-)