how can add extra audio streams codecs to my files before they get uploaded

[aniel]

I am trying to add extra audio streams to my files with both 7.1, 5.1 and 2.0 respectively (aac, ac3, eac3, truehd, dts to aac, ac3, eac3, truehd, dts). How do I go about doing this? I have tried using both tdarr and unmanic, but I don't know what I'm doing. I want take whatever audio the files come with and duplicate it/add extra audio streams with different audio codecs such as aac, ac3, eac3, truehd, dts as well different audio channels such as 7.1, 5.1 and 2.0 respectively, although I am not sure if 5.1 to 7.1 is possible or even necessary.

[ProWo]

Add the audiostreams you like with Mkvtoolnix.

[aniel]

i just played around with Mkvtoolnix and i didn't see any option for adding extra audio streams/codecs from the original audio, same for downmixing to 5.1 and 2.0

[ProWo]

Drag & drop the new audiostream to the upper window, then click start multiplex.

[aniel]

i dont have a new audio stream, the new audio streams would need to be converted from the one that the file comes with

[abolibibelot]

MKVToolNix does not reencode, it only allows to mux existing streams into the MKV container. So you would have to first demux and convert the audio, with ffmpeg or eac3to, or a GUI software relying on those command line tools under-the-hood, like MeGUI, then remux with MKVToolNix (or ffmpeg). But learning how to use MeGUI is not necessarily easier than learning basic commands to run those tools directly, and if I remember correctly it doesn't allow to convert only the audio without re-compressing the video. At this point I consider MeGUI merely as a convenient way to download and update a variety of command line tools from one place.