I have a longtime running video project about a game that's around 1h30 playtime, and I natively rendered it in 8K (true 8K). To complement the video's quality I also have the surround track and stereo track recorded seperatly. Now, YouTube recommends AAC-LC with a 'Stereo or Stereo + 5.1' and it's that last option that confuses me. You can find the information here.
How can I create a 'stereo + 5.1' track. Is that just a video file with two tracks? As far as I remember, YouTube will automatically create a stereo track from the surround one if it's the only track in the file, but I'd prefer it to be the real stereo track as the mixing in-game did a much better job than the result from downmixing the surround track either myself or automatically by YouTube.
I tried getting this result by having the video file and two audio files mixed with ffmpeg like this:
ffmpeg -i video.mkv -i surround.wav -i stereo.wav -map 0:v:0 -map 1:a:0 -map 2:a:0 -c:v copy -c:a:0 eac3 -ac:a:0 6 output_testyt2.mp4
But it doesn't work. I don't even get surround this way, it will always select the stereo track and that's it (no surround option available in YouTube TV). So far I've only had surround + stereo by only including the surround track directly as the single option so YouTube creates an automatic downmix.
Any help with this issue, or someone who knows what the article is talking about?
