Ask HN: Seeking device to normalize audio output for consistent volume levels

It's been a problem w/ Hollywood movies since "home theater" came out. That is, a really boomy soundtrack adds to the emotional impact when you are in a closed room but in an open space where people come in and out (where there average TV is) it's totally inappropriate.

Systems like Atmos that decompose the sound track into components might help but they're likely to get used for the wrong reason -- in the last 10 years Hollywood gave up on making the vocals in movies legible, which has the positive effect that a lot of people are used to reading subtitles, which is why you can find subtitled anime [1], Italian crime dramas [2] and such in downmarket places like Tubi these days.

(Maybe it's why my acting coach who yelled at me to enunciate the same way my wife yells at horse riders to keep their heels down is here and not in LA)

[1] https://tubitv.com/series/2082/accel-world [2] https://tubitv.com/movies/571052/mafia-millionaires-subbed

If your source is Dolby Digital, you may not need anything new - just adjusting your settings. Dynamic range compression is a standard feature, and the bitstream should already include the necessary metadata for the decoder to implement this.

It's been a while since I looked into this in detail, but iirc the decoder must automatically enable dynamic range compression when it's set to two channel output. So avoid configurations where you first convert the audio to 5.1 channel PCM or analog, and then apply downmixing or virtual surround.

If you're using a surround system, most receivers have a night mode as mentioned by others already. Some have also an adaptive system that adjusts the dynamic range based on your volume setting - turn it up and you get the full dynamic range, turn it down and the dynamic range is compressed more as you set the volume lower to try to keep the dialog audible. Many receivers include a microphone for automatic settings, and after calibration know the actual output level. The Dolby Digital bitstream (and I think DTS) include a flag to indicate the overall dialog level, and based on these a receiver can do quite a good job. Some I think go only by the DD metadata, others have a compressor that can be applied to any input.

And also the Infuse app

I'd go get a pro rackmount compressor on Ebay first

https://www.ebay.com/sch/i.html?_nkw=audio+compressor

I had fond memories of using one at the KTEK college radio station where I was (first) the public relations officer and (later) the engineer. I was told we got it so that amateur DJs wouldn't saturate the transmitter. When I told my high school physics teacher (a classical music audiophile) about it I got a sharp talking to about how it hurts audio quality. Today I know it was an early shot in "the loudness wars".

(If you're listening in a car or other noisy environment, dynamic range is a bug and not a feature, however.)

6-channels would be enough for the typical 5.1 system but the "stereo" label on that expensive box makes it seem like it wouldn't do the right thing for home theater, where I think you'd want to reduce the gain in all 6 of the channel by the same amount.

I gave up and started sleeping.