Volume control is not working

[rojasgabriel]

Hi everyone. Firstly, thank you for creating such a great app. My issue is that although the brightness works perfectly, the volume control doesn't. Even though I can see the slider changing values, the actual audio doesn't change volume. I exported the display information I got from BetterDisplay here:

Display Information
BetterDisplay Version 4.1.5 Build 47757

DELL S2725QS - Third-party external display - Connected

Identifiers
-----------
Tag ID: 3
Serial number: 31364F4C
Vendor ID: 10AC (DEL)
Model ID: A277
Product name: DELL S2725QS
Alphanumeric serial: 9NTC364
Year of manufacture: 2025
Week of manufacture: 8
UUID: 28F3ADF0-647D-4E0C-900C-79F54424B4A9
Dimensions (unrotated): 601.38mm x 340.24mm
Registry location: IOService:/AppleARMPE/arm-io@10F00000/AppleT811xIO/dispext0@70000000/AppleCLCD2
Metal device: Apple M2
Platform: Apple Silicon
I2C service name: DCPAVServiceProxy
DDC messaging: Standard
CGDirectDisplayID: 2
Configuration run ID: 3012
First added: May 11, 2025 at 7:15:47 PM
Last detected: Mar 5, 2026 at 10:41:12 PM
Last undetected: Mar 5, 2026 at 10:40:55 PM

Capabilities
------------
Software control: Yes
Hardware control (Apple): No
Color table alteration capable: Yes
Potentially DDC compatible: Yes
Supports proper HiDPI: Yes
Supports changing orientation: Yes
Supports variable refresh rate: No
Supports Apple Display Presets: No
Supports Color Profiles: Yes
XDR/HDR upscaling compatible: Yes
Supports HDR: Yes
Potential EDR: 1.0
Reference EDR: 1.0
Horizontal GPU resolution limit: 3072 pixels HiDPI (6144 pixels LoDPI)

Current Display Mode
--------------------
Mode number: 84
Logical width: 2048
Logical height: 1152
HiDPI: Yes
Pixel width: 4096
Pixel height: 2304
Bits per sample: 10
Samples per pixel: 3
Bits per pixel: 32
Pixel encoding: --RRRRRRRRRRGGGGGGGGGGBBBBBBBBBB��������������������������������
1:1 pixel mapped resolution: No
Default resolution: No
Refresh string: 60Hz
Variable refresh rate: No
Max refresh rate: 60
Min refresh rate: 60
Fixed-point refresh rate: 3,932,160 (interpreted as 60.000000)
Row bytes: 16384
Horizontal density: 173
Vertical density: 172
Flags: 00000003
Unsafe mode: No
Invalid mode: No

Current Display Mode (Connection Level)
---------------------------------------
Description:  3840 x 2160 YCbCr422 10bit limited
Dimensions: 3840 x 2160
Refresh Rate: 59.99999865889549
Variable Refresh Rate: No
Bit Depth: 10 bits per sample
Color Mode: YCbCr422LimitedRange
YCbCr: Yes
HDR/SDR Mode: SDR
Color Gamut: gamut_SRGB
Virtual: No
Pixel Aspect Ratio: 1.0
Preferred Scale: 2

Preferred Display Mode (Connection Level)
-----------------------------------------
Description:  3840 x 2160 YCbCr422 10bit limited
Dimensions: 3840 x 2160
Refresh Rate: 59.99999865889549
Variable Refresh Rate: No
Bit Depth: 10 bits per sample
Color Mode: YCbCr422LimitedRange
YCbCr: Yes
HDR/SDR Mode: SDR
Color Gamut: gamut_SRGB
Virtual: No
Pixel Aspect Ratio: 1.0
Preferred Scale: 2

Sidecar Configuration
---------------------
Name: DELL S2725QS
Sidecar UUID: n/a
State: Unknown

Color Profile Configuration
---------------------------
Custom Profiles / 1: file:///Library/ColorSync/Profiles/Displays/DELL%20S2725QS-28F3ADF0-647D-4E0C-900C-79F54424B4A9.icc
Custom Profiles / HDMI HD: file:///System/Library/ColorSync/Profiles/Display%20P3.icc
Device Class: mntr
Device Description: DELL S2725QS
Device Host Scope: kCFPreferencesCurrentHost
Device ID: <CFUUID 0xabd042680> 28F3ADF0-647D-4E0C-900C-79F54424B4A9
Device User Scope: kCFPreferencesAnyUser
Factory Profiles / Device Default Profile ID: HDMI HD
Factory Profiles / HDMI HD / Device Mode Description: HDMI HD
Factory Profiles / HDMI HD / Device Profile URL: file:///Library/ColorSync/Profiles/Displays/DELL%20S2725QS-28F3ADF0-647D-4E0C-900C-79F54424B4A9.icc
Factory Profiles / HDMI SD / Device Mode Description: HDMI SD
Factory Profiles / HDMI SD / Device Profile URL: file:///System/Library/CoreServices/Resources/Profiles/SD%20170M-A.icc

Display Information
-------------------
Display Supports Rotation: 1 (Yes)
Display Is Exclusive: 0 (No)
IO Display Is HDMI Sink: 1 (Yes)
Display Horizontal Image Size: 600
Display Supports Dynamic Geometry: 0 (No)
Display Blue Point X: 0.1386719
Display Product ID: 41,591
Display Year Manufacture: 2,025
Display Is Virtual Device: 0 (No)
Display Blue Point Y: 0.05761719
Slope Limit Gamma: 0 (No)
Display-icon: public.display
Display UUID: 28F3ADF0-647D-4E0C-900C-79F54424B4A9
Display Transport Type: 1 (Yes)
Display Is Air Play: 0 (No)
Display Product Name / Hr_ HR: DELL S2725QS
Display Product Name / Ko_ KR: DELL S2725QS
Display Product Name / Nb_ NO: DELL S2725QS
Display Product Name / Id: DELL S2725QS
Display Product Name / Hu_ HU: DELL S2725QS
Display Product Name / Cs_ CZ: DELL S2725QS
Display Product Name / Sl_ SI: DELL S2725QS
Display Product Name / Da_ DK: DELL S2725QS
Display Product Name / Uk_ UA: DELL S2725QS
Display Product Name / Fr_ CA: DELL S2725QS
Display Product Name / It_ IT: DELL S2725QS
Display Product Name / Zh_ TW: DELL S2725QS
Display Product Name / Ar: DELL S2725QS
Display Product Name / He_ IL: DELL S2725QS
Display Product Name / Es_ ES: DELL S2725QS
Display Product Name / Nl_ NL: DELL S2725QS
Display Product Name / Fi_ FI: DELL S2725QS
Display Product Name / Ro_ RO: DELL S2725QS
Display Product Name / Vi_ VN: DELL S2725QS
Display Product Name / Sk_ SK: DELL S2725QS
Display Product Name / Zh_ CN: DELL S2725QS
Display Product Name / Ru_ RU: DELL S2725QS
Display Product Name / En_ GB: DELL S2725QS
Display Product Name / Fr_ FR: DELL S2725QS
Display Product Name / Ms: DELL S2725QS
Display Product Name / Hi_ IN: DELL S2725QS
Display Product Name / Th_ TH: DELL S2725QS
Display Product Name / Ca_ ES: DELL S2725QS
Display Product Name / Es_ XL: DELL S2725QS
Display Product Name / En_ AU: DELL S2725QS
Display Product Name / De_ DE: DELL S2725QS
Display Product Name / En_ US: DELL S2725QS
Display Product Name / Pt_ BR: DELL S2725QS
Display Product Name / Pl_ PL: DELL S2725QS
Display Product Name / El_ GR: DELL S2725QS
Display Product Name / Sv_ SE: DELL S2725QS
Display Product Name / Tr_ TR: DELL S2725QS
Display Product Name / Ja_ JP: DELL S2725QS
Display Product Name / Pt_ PT: DELL S2725QS
Display Green Point X: 0.3007812
Display Vertical Image Size: 340
Display White Gamma: 1.961
Display Is SLVD Exclusive: 0 (No)
Display Serial Number: 825,642,828
Display Pixel Width: 3,840
Display Week Manufacture: 8
Display Green Point Y: 0.6142578
IO Display Is Digital: 1 (Yes)
IO Display Location: IOService:/AppleARMPE/arm-io@10F00000/AppleT811xIO/dispext0@70000000/AppleCLCD2
Display Pixel Height: 2,160
Display ID: 2
Display White Point X: 0.3134766
Display Is Presentation Display: 0 (No)
Display Is Presentation Mode Enabled: 0 (No)
Display DPI Cutoff: 300
Display Vendor ID: 4,268
Display CA Device Name: external-0
Display Dynamic Geometry Enabled: 0 (No)
Display White Point Y: 0.3291016
Display Is DFR: 0 (No)
Display Supports Underscan: 0 (No)
Display Red Point X: 0.6748047
Display Bundle URL: /System/Library/Displays
Display Red Point Y: 0.3222656
Aspect Ratio: 15
Chromaticity / Blue / X: 9,088
Chromaticity / Blue / Y: 3,776
Chromaticity / Green / X: 19,712
Chromaticity / Green / Y: 40,256
Chromaticity / Red / X: 44,224
Chromaticity / Red / Y: 21,120
Continuous Frequency Support: None
Default Color Space Is SRGB: 0 (No)
Default White Point / Gamma: 144,179
Default White Point / X: 20,544
Default White Point / Y: 21,568
Has HDMI Legacy EDID: 0 (No)
Luminance / Max: 27,375,011
Luminance / Max Frame Average: 27,375,011
Luminance / Min: 6,399
Max Horizontal Image Size: 60
Max Vertical Image Size: 34
Maximum Refresh Rate: 240
Maximum Variable Refresh Rate: 15,728,640
Minimum Refresh Rate: 96
Minimum Variable Refresh Rate: 6,291,456
Port ID: 0 (No)
Precise Aspect Ratio: 115,652
Product Attributes / Alphanumeric Serial Number: 9NTC364
Product Attributes / Legacy Manufacturer ID: 4,268
Product Attributes / Manufacturer ID: DEL
Product Attributes / Product ID: 41,591
Product Attributes / Product Name: DELL S2725QS
Product Attributes / Serial Number: 825,642,828
Product Attributes / Week Of Manufacture: 8
Product Attributes / Year Of Manufacture: 2,025
Supports Active Off: 1 (Yes)
Supports BT 2020 RGB: 512
Supports BT 2020 YCC: 128
Supports BT 2020c YCC: 0 (No)
Supports Discrete Media Refresh Rate: 0 (No)
Supports HDR Gamma EOTF: 0 (No)
Supports HDR Static Metadata Type 1: 1 (Yes)
Supports HLGEOTF: 0 (No)
Supports PQEOTF: 1 (Yes)
Supports Standby: 1 (Yes)
Supports Suspend: 1 (Yes)
Supports Variable Refresh Rate: 0 (No)
Variable Refresh Rate Requires Ramp Rate Limits: 0 (No)
White Points - 1 / Gamma: 144,179
White Points - 1 / X: 20,544
White Points - 1 / Y: 21,568
White Points - 2 / Gamma: 144,179
White Points - 2 / X: 20,544
White Points - 2 / Y: 21,568
Bounds: NSRect: {{0, 0}, {4096, 2304}}
Cloned: 0 (No)
Cloning: 0 (No)
Cloning Supported: 0 (No)
Connection Seed: 15
Container Id: 
Current Orientation: rot0
Device Name: external-0
Display Id: 2
Display Type: 1 (Yes)
External: 1 (Yes)
External Display Attributes / Bt 2020 YCC: 2
External Display Attributes / Dolby Vision: 0 (No)
External Display Attributes / Hdr Static Metadata Type 1: 2
External Display Attributes / Legacy HDMIEDID: 0 (No)
External Display Attributes / Manufacturer ID: 4,268
External Display Attributes / Pq EOTF: 2
External Display Attributes / Product ID: 41,591
External Display Attributes / Serial Number: 825,642,828
External Display Attributes / Week Of Manufacture: 8
External Display Attributes / Year Of Manufacture: 2,025
Frame: NSRect: {{0, 0}, {3840, 2160}}
Has Native Frame Rate Request: 0 (No)
Heartbeat Rate: 0.01666666666666667
Is Reference: 0 (No)
Is Reference Limited: 0 (No)
Latency: 0 (No)
Link Quality: -1
Logical Scale: NSSize: {1.0666667222976685, 1.0666667222976685}
Maximum Logical Scale: 1.600000023841858
Minimum Frame Duration: 1 (Yes)
Minimum Logical Scale: 0.25
Name: External
Native Orientation: rot0
Native Size: NSSize: {3840, 2160}
Od LUT Version: 0 (No)
Overscan Adjustment: scaleContent
Overscan Amount: 1 (Yes)
Overscan Amounts: NSSize: {1, 1}
Overscanned: 0 (No)
Physical Size: NSSize: {23.622047424316406, 13.385826110839844}
Point Scale: 1 (Yes)
Process Id: 0 (No)
Product Name: DELL S2725QS
Refresh Rate: 0.01666666666666667
Safe Bounds: NSRect: {{0, 0}, {4096, 2304}}
Seed: 40
Supported: 1 (Yes)
Supports Extended Colors: 0 (No)
Tag: 0 (No)
Transport Type: dp
Unique Id: 10AC77A2-0000-0000-0823-0103803C2278

I'm not too sure if my monitor is capable of adjusting volume through software or not. I'm on MacOS Tahoe 26.3.

[waydabber]

Do you have DDC brightness control working properly? What does the DDC report say under Configure DDC / Detect...?

(Note: you seem to have YCbCr422LimitedRange as current color mode - this will make some of the colors look bad)

[rojasgabriel]

The brightness works great. It's just the audio that doesn't. Here's what the DDC report says:

And thanks for the note on the color mode. I'll look into that.