No sound through HDMI cable

Question

Level 1

8 points

No sound through HDMI cable

OK, I've checked a lot of threads but have not found any resolutions. I have a Mac Pro 5,1 with 64 GB memory, 2x6 core 3.46 Xeon processors, running Mojave 3. I have a Radeon RX560 graphics card hooked up through an HDMI cable to a LG 32-Inch IPS Monitor with speakers. No sound is coming from the speakers. I have gone to system settings - sound - Play sound effects through: but only options are, internal speakers, line out, digital out and my bluetooth speaker. Output shows the same options. Input varies sightly with the addition os my USB camera. I've also gone to system settings - display. It lists my monitor at the top, display and color buttons and mirroring options checked. Finally, I've gone to Audio MIDI Setup. On the left there are 2 Mic inputs (line & digital), 3 speaker outputs (output, line & digital. There is also a USB shown for my webcam and my bluetooth speaker. There is no HDMI option in either input or output settings. I've tried adding HDMI by using the "+" at the bottom of the window, but t wasn't an option.

Can anyone help?

Mac Pro, 10.14

Posted on Jan 29, 2019 11:02 AM

Reply

Answer 1

Top-ranking reply

John Lockwood

Level 6

13,697 points

Jan 31, 2019 8:50 AM in response to soxman7

I think it started with Sierra but Since High Sierra 10.13.4 including Mojave Apple have made matters much, much harder.

For some unknown and really annoying reason Apple have deliberately chosen to cripple - that is deliberately disable the ability to do audio over HDMI.

Originally this could be solved by 'only' installing a 3rd party KEXT driver - although being unsigned you had to turn off SIP for this to work. With Mojave as I mentioned this is now more complex. Apparently you now also need to replace the Apple AppleALC.kext driver with an older version and hexedit one of Apple's drivers to use the PCI card ID number for your video card instead of one of the apparently only 2 models of card Apple officially allow audio via HDMI on.

See this now very, very long thread about this. (The length shows you how long, and how annoying this is.)

https://forums.macrumors.com/threads/hdmi-displayport-audio-fix.2147525/

in particular - https://forums.macrumors.com/threads/guide-hdmi-audio.1499797/page-28#post-25999498

See also

https://forums.macrumors.com/threads/hdmi-displayport-audio-fix.2147525/

Ironically the first High Sierra beta supported HDMI audio 'out of the box' which just goes to show you this is an Apple software issue not a hardware issue.

Reply

Answer 2

Feb 3, 2019 9:03 AM in response to soxman7

I have not tried this for Mojave or later High Sierra versions myself - I have given up for the moment.

However see - https://forums.macrumors.com/threads/guide-hdmi-audio.1499797/page-29#post-26135962

It would be possible to the same using a GUI hexeditor but you might have to boot from a different drive to do this due to security measures. The Perl command might work via the Recovery partition in Terminal. You definitely need SIP turned off.

If you get the numbers wrong it might fail to boot afterwards so make a note of the original value and then you can repeat the command the opposite way round to reverse the change. (You might have to boot from another drive or the Recovery partition to do this.)

The value in System Report might look like 0x0166. The 0x you ignore and it is the four characters after that e.g. 0166 you need. As per the above message you first change the order to 6601. In the

/System/Library/Extensions/AppleHDA.kext/Contents/PlugIns/AppleHDAController.kext/Contents/MacOS/AppleHDAController

file it is preceded by de10 so the search string is the original value of de101a0e and the new value is de10xxxx where xxxx is your Macs video card value.

Reply

Answer 3

Jan 29, 2019 11:43 AM in response to soxman7

If no sound output is showing, that is trying to tell you the HDMI port on that card does not feature sound.

It is much more likely to be supported on a DisplayPort family connection.

Reply

Answer 4

lllaass

Level 10

210,519 points

Jan 29, 2019 12:30 PM in response to soxman7

Ner the end of the comments in the following also say no audio via HDMI for 560 and Mojave

https://blog.macsales.com/46029-make-your-mac-pro-tower-mojave-compatible-with-a-gpu-upgrade

Reply

Answer 5

Feb 3, 2019 7:38 AM in response to soxman7

What model LG display? Does it have any other Inputs?

Reply

Answer 6

soxman7 Author

Level 1

8 points

Feb 3, 2019 6:21 AM in response to John Lockwood

Thanks John for the helpful info and links. I followed the info in the 1st link and now my monitor is listed in the sound output with HDMI. It also shows up in system hardware audio. My Mac definitely sees the HDMI audio link of the monitor. I still have no sound at the monitor. I am using a Radeon RX560 graphics card. You had mentioned it may be necessary to "hexedit one of Apple's drivers to use the PCI card ID number for your video card instead of one of the apparently only 2 models of card Apple officially allow audio via HDMI on". How do I do that?

Reply