Dialogue too quiet with multichannel audio on stereo speakers

[vladdus]

Hi, I’m trying to figure out whether this is expected mpv behavior or whether I’m misunderstanding how downmixing is supposed to work.

I’m using mpv on macOS with a pair of simple stereo USB desktop speakers (Creative Pebble V3). Regular stereo content sounds completely normal, so the speakers themselves seem fine.

The issue only shows up with multichannel movie audio (DTS, AC3, E-AC3, etc.). Dialogue often sounds noticeably quieter than music / sound effects when playing the original multichannel track downmixed to stereo.

What’s throwing me off is that the exact same MKV files sound much better in MPC-HC / MPC-BE on Windows using the same speakers, so I don’t think the source files are the issue.

This is my current configuration, which doesn't seem to make much of a difference:

# =========================
# Global Audio
# =========================
audio-channels=stereo
audio-normalize-downmix=no

# =========================
# 7.1 Surround Downmix
# =========================
[Downmix-7-1]
profile-cond=p["audio-params/channel-count"] >= 7
profile-restore=copy
af=pan=stereo|FL=0.5*FL+0.8*FC+0.3*SL+0.3*BL+0.15*LFE|FR=0.5*FR+0.8*FC+0.3*SR+0.3*BR+0.15*LFE,acompressor=threshold=-20dB:ratio=2:attack=20:release=250:makeup=2

# =========================
# 5.1 Surround Downmix
# =========================
[Downmix-5-1]
profile-cond=p["audio-params/channel-count"] > 2 and p["audio-params/channel-count"] < 7
profile-restore=copy
af=pan=stereo|FL=0.6*FL+0.8*FC+0.3*SL+0.1*LFE|FR=0.6*FR+0.8*FC+0.3*SR+0.1*LFE,acompressor=threshold=-20dB:ratio=2:attack=20:release=250:makeup=2

# =========================
# Mono Audio Handling
# =========================
[Mono]
profile-cond=p["audio-params/channel-count"] == 1
profile-restore=copy
af=lavfi=[pan=stereo|FL=c0|FR=c0],acompressor=threshold=-16dB:ratio=3.5:attack=15:release=200:makeup=4

The one thing that does consistently work is converting the same multichannel audio track offline with ffmpeg into a stereo AAC track. That version sounds much more balanced immediately on the same hardware.

So now I’m wondering if this is just expected behavior (mpv doing a more “accurate” theatrical downmix while something like MPC/LAV applies more consumer-friendly processing by default).

Is there a recommended way in mpv to get better stereo playback for multichannel movie audio on simple desktop speakers? Something closer to “night mode” / dialogue-friendly playback rather than a strict reference downmix?

Just trying to understand whether I’m chasing the wrong thing here. Thanks.

[hooke007]

#8418

[vladdus]

Thank you!

For anyone wondering, I used the following config:

audio-channels=stereo
af="lowshelf=frequency=100:gain=-2.5,dynaudnorm=compress=27.0:gausssize=53"

It seems to have mostly fixed the audio issues; content plays quite nicely now.