The following mpv options support ReplayGain:

• replaygain
• replaygain-preamp
• replaygain-clip
• replaygain-fallback

By default mpv ignores ReplayGain tags. Currently users must enable this feature using a mpv configuration file or by setting these options in IINA's Advanced settings.

The commit adds a direct mapping to these options. The default values for the IINA settings match mpv:

• replaygain: no
• replaygain-preamp: 0
• replaygain-clip: no
• replaygain-fallback: 0

So by default IINA will ignore ReplayGain tags.

The default settings look like:

With ReplayGain enabled the settings look like:

To test this feature I installed rsgain using brew:

brew install complexlogic/tap/rsgain

And then ran it over a set of mp3 files:

low-batt@gag issue-4915$ rsgain easy -m 10 .
[✔] Building directory tree...
[✔] Found 2 directories...
[✔] Scanning directories for files...

Scanning Complete
Time Elapsed:      00:00:06
Files Scanned:     9
Clip Adjustments:  0 (0.0% of files)
Average Gain:      -5.98 dB
Average Peak:      1.000000 (0.00 dB)
Negative Gains:    9 (100.0% of files)
Positive Gains:    0 (0.0% of files)

low-batt@gag issue-4915$ 

Playing one of those files with ReplayGain enabled the mpv log contains ReplayGain related messages:

[  70.271][v][cplayer] Replaygain: Track=-5.980000/1.000000 Album=-5.980000/1.000000
[  70.271][v][cplayer] Applying replay-gain: 0.502343
[  70.271][v][cplayer] ...with clipping prevention: 0.502343

The mpv track-list property contains ReplayGain information:

• track-list/N/replaygain-track-peak
• track-list/N/replaygain-track-gain
• track-list/N/replaygain-album-peak
• track-list/N/replaygain-album-gain

I considered adding ReplayGain information to the Inspector window, but was uncertain how to integrate that information from a UI design perspective. This can be a separate enhancement. Currently the ability to configure properties to watch can be used: