I need to detect the average volume of the left and right channels of an MP3, considered separately (e.g., to detect when one channel is louder than the other).
The ffmpeg volumedetect filter really, really wants to work on both channels at once. I thought maybe something like this would work, but it is still averaging the two of them, and producing the same output twice:
ffmpeg -hide_banner -i IN.mp3 -filter_complex 'channelsplit=channel_layout=stereo; [0:0:0]volumedetect; [0:0:1]volumedetect' -f null /dev/null
I can do it by writing a temporary file with each channel and then examining them again, but that's a lot slower because these are really big files. So I'd rather do it in one pass.