Volume Keys not working with HDMI audio on mac OSX Lion?

I have a mac mini 2011 with OSX Lion. And I have connected my monitor (with integrated speakers) through hdmi port. The sound is working fine, but the volume keys on the keyboard don't work. When I press one of them the volume image appears on the screen but with a prohibited signal.

Is there a way to fix this and make my keyboard keys change the system volume?

By the way, they work very well when I use another audio output device

Solution 1:

See a solution here for the problem - http://www.vanetta.net/2012/07/enabling-hdmi-audio-controls-on-2011.html

Requires the free third party app - https://code.google.com/p/soundflower/ but it works perfectly.

Solution 2:

The audio signal over HDMI is encoded. Encoded audio streams should be normalized to 0 dB. You cannot change this behavior as the audio signal would not be normalized anymore. You can only use the volume controls of your TV set.

Some programs (like iTunes) have volume control themselves, those can be used to change the volume of that specific program. (Although this goes somewhat against the principle that HDMI audio should be normalized.)

See also this discussion on Apple Support Communities (same answer).

Solution 3:

Install Homebrew:

ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
Install Cask

brew install caskroom/cask/brew-cask
Install Soundflower:

brew cask install soundflower
Reboot.
Start soundflowerbed (find it by pressing cmd-space to open spotlight):
Click the Soundflower icon in the top-right and select your output device (You should pick HDMI instead of DisplayPort):
In the sound preferences, pick Soundflower:

Solution 4:

As SoundFlower is extremely outdated and not actively maintained. I've started looking for a better solution.

I highly recommend this, works pretty great on my LG monitor: https://github.com/MonitorControl/MonitorControl

This project also supports the default volume/brightness keyboard controls. Instead of using a digital line like SoundFlower, it tries to change the volume of your display itself.

Edit:

Since posting this answer, I've become a maintainer of this project, and it's grown quite a bit.

I would still recommend it to everyone wanting to change volume/brightness on external monitors. Works on both Intel and ARM

Solution 5:

A solution using the free version of Sound Siphon

To solve both of these issues: Launch the Sound Siphon app. In Sound Siphon’s preferences select your output device as the pass through device. Turn Sound Siphon on.

Sound Siphon processes the audio before it goes to your output device. Now you can use your keyboard to control the volume"

http://staticz.com/add-keyboard-volume-controls/