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by dkarp 1895 days ago
Downmixes audio on movies from surround sound to stereo balanced for night watching (prevents audio being too quiet) so that they can direct stream on my devices

  ffmpeg -hide_banner -loglevel error -nostdin -y -i "$f" -map 0:0 -c:v copy -map 0:a:0? -c:a:0 aac -b:a:0 160k -filter:a:0 "pan=stereo|FL=1.414*FC+0.707*FL+0.5*FLC+0.5*BL+0.5*SL+0.5*LFE|FR=1.414*FC+0.707*FR+0.5*FRC+0.5*BR+0.5*SR+0.5*LFE,acompressor=ratio=4" -metadata:s:a:0 title="NightMixed" -metadata:s:a:0 language=eng -disposition:a:0 default -map 0:a:0? -c:a:1 copy -disposition:a:1 none -map 0:a:1? -c:a:2 copy -disposition:a:2 none -map 0:a:2? -c:a:3 copy -disposition:a:3 none -map 0:a:3? -c:a:4 copy -disposition:a:4 none -map 0:a:4? -c:a:5 copy -disposition:a:5 none -map 0:a:5? -c:a:6 copy -disposition:a:6 none -map 0:a:6? -c:a:7 copy -disposition:a:7 none -map 0:a:7? -c:a:8 copy -disposition:a:8 none -map 0:a:8? -c:a:9 copy -disposition:a:9 none -map 0:s:0? -c:s:0 copy -map 0:s:1? -c:s:1 copy -map 0:s:2? -c:s:2 copy -map 0:s:3? -c:s:3 copy -map 0:s:4? -c:s:4 copy -map 0:s:5? -c:s:5 copy -map 0:s:6? -c:s:6 copy -map 0:s:7? -c:s:7 copy -map 0:s:8? -c:s:8 copy -map 0:s:9? -c:s:9 copy "/home/pi/media/remixed_in_progress/$f"
1 comments

Goddammit I can't believe how downmixing x.y to 2.0 isn't a solved problem by now and is so broken through and through.

I mean, it's never ever done in a way that doesn't produce quiet dialog that makes you raise volume and loud sounds that makes your eardrums bleed. Like, even basic audio normalisation would produce half-decent results, but no we get crazy contrast by default and constant volume switching.

The interesting part is that most media is being consumed with stereo audio down-mixing. Everyone streaming content on their laptops, with their television's speakers or with a sound bar. Yet all the audio is recorded and mastered for surround sound systems, even though they could include mastered stereo audio without the down-mixing issues like quiet audio.