No sound from video card

[geomcd1949]

Ubuntu 12.10 fresh install
HIS iCooler H775F1GD Radeon 7750 1GB 128-bit GDDR5 video card
ASRock Z77 Extreme4 motherboard
Intel Core i7 3770 Ivy Bridge 3.4GHz cpu
ASUS monitor with built-in speakers

Connection from video card to monitor is by HDMI cable.

With video card installed, and HDMI cable from the video-card outlet to the monitor, no sound is played. Systems Setting>Sound gives three options to "Play sound through:" Digital Outout (S/PDIF); Headphones; and Analog Output. No sound is heard when any of these three are selected. I can play sound,however, if I connect external speakers by means of a jack into the Audio Out port on the I/O panel, and select Analog Output.

If I uninstall the video card, in the Systems Settings>Sound, "Play sound through," I now get a fourth option listed, HDMI/Display Port 3, and can play sound by selecting this and connecting the HDMI cable from the I/O Panel to the monitor.

I suspect this is a video-card driver problem, but not experienced enough to be sure. Advice and guidance greatly appreciated.

~George

[geomcd1949]

Found the following as I continued to research the problem. It seems the solution might be in the last clause, and I ask if I can get an explanation of what the writer means by "but you can activate it by adding radeon.audio=1 as a kernel boot parameter (https://help.ubuntu.com/community/BootOptions#Changing_boot_options_Permanently_for_ an_Existing_Installation)."




"As mentioned in an earlier post (http://voices.canonical.com/david.henningsson/2011/09/06/pulseaudio-with-jack-detection/), much HDMI/DisplayPort hardware have phantom outputs, and there is no way we know what outputs are real until something is plugged in. With the new sound settings UI in Ubuntu 12.04, we finally have a good user experience in this scenario: Only the outputs that are actually plugged in and possible to activate will be shown.
http://voices.canonical.com/david.henningsson/files/2012/04/sound-settings-ui2.png
Sound settings in Ubuntu 12.04
Video drivers

Most of the code to activate HDMI/DisplayPort audio is in the video driver, rather than the audio driver. Therefore, if this is not working, it is more likely that the problem is within the video driver.
It is also notable that the open source driver for ATI/AMD (called radeon), has experimental support for HDMI/DisplayPort audio, at least for some cards. It is disabled by default (https://lists.ubuntu.com/archives/kernel-team/2012-February/018898.html), but you can activate it by adding radeon.audio=1 as a kernel boot parameter (https://help.ubuntu.com/community/BootOptions#Changing_boot_options_Permanently_for_ an_Existing_Installation)."


Thanks.


~George