I'm trying to connect my desktop Ubuntu computer to my TV to act as a media PC. I've got it connected using a DVI to HDMI cable and video is working fine. But I cannot get the sound to work. I've tried plugging headphones into my computer and I get nothing. I've also tried plugging an iPod into the HDMI audio-in on the TV and also get nothing. So I suspect there might be two separate problems here.

I've checked the manuals for both my desktop computer and the TV. I'm definitely plugged into the right port on my desktop to get a line signal out, but I don't seem to be getting one. The TV's manual doesn't specifically say that it takes a line signal, but it has L and R RCA plugs so I'm assuming that's for line. I'm trying to connect them with an RCA to headphone jack cable that I've tested elsewhere and know is good.

I'm starting to suspect that my issue, or at least one of them, might be to do with the Ubuntu sound drivers, since I can't seem to get my computer to even put out any sound to headphones. But the desktop I'm using is a very popular model so it surprises me that it would have driver issues. But being somewhat of a noob when it comes to desktop linux (I mostly work with Mac and Windows, and occasionally command line linux on servers), I'm not sure how to diagnose or fix this.

As for the TV, I've got through all of its menu options and can't find anything that might relate to this.

The desktop is an HP Pavilion A6600F (totally stock) running Ubuntu 9.04. The TV is a Magnavox 32MF339B LCD HDTV.

I've spent hours messing with this and am thoroughly frustrated. Any help would be appreciated!

EDIT: Just upgraded to Ubuntu 9.10 (the update manager told me that 9.10 was the latest version, then told me after 9.10 was done that I should update to 10.04) and I'm now finally getting a line signal out of the headphone jack! Still can't get it to come out on the TV though...

EDIT 2: Called tech support for Magnavox and they were completely puzzled but eventually decided it's a hardware issue with the TV which is still under warranty. They said the warranty will cover parts but not labor for repair. They gave me a local number to call during business hours tomorrow.

On your TV do you may have to use the menu to associate the line in (RCA jacks) with the video source. The TV is probably expecting sound over HDMI by default and not auto switching to the RCA jacks.

The other possibility is that there is a specific set of RCA jacks associated with the HDMI input. There may be a different HDMI input that works with the RCA jacks. On my TV one of the HDMI inputs has an associated set of RCA jacks and one does not.

For digital sound the DVI->HDMI connection may prevent it. DVI technically supports HDMI audio, but a given video card is not guaranteed to support it. Using Linux doesn't make that any easier.

Make sure whatever you are sending over HDMI audio from any source is plain 2 channel PCM. A lot of TVs aren't smart enough to deal with or pass compressed or multichannel audio.

Ubuntu's sound drivers a generally a mess, can't help much there. If you must use Linux I've had much better luck with Fedora for audio.