I own a GeForce 9600 GT which is connected to my Samsung HDTV (LE32A586) by a DVI -> HDMI connector. My card doesn't have spdif input to send audio through HDMI, so I've added a jack -> stereo RCA cable (according to my TV manual).
That TV (and others) doesn't allow you to choose the audio input, but automatically fallback to the analog stereo input if there isn't any from the HDMI port.
The issue is that my TV detects sound from my video card and ignores the analog output.
I did a simple test to find out where the problem came from :
1. I play a sound on my graphic session (X configured to use nvidia-driver v177.82), but I hear no sound on my TV.
2. While the sound plays, I switch to the console and then I hear the sound playing (2.6.27 kernel frambuffer driver).
The only reason why the sound may play in console and not in graphic mode - although the card and connections are the same - is that the nvidia driver behaves differently, activating some flag on the DVI output that tells my TV sounds come through HDMI, which the kernel framebuffer driver doesn't.
I found two similar topics addressing this issue, by linux and windows vista users :
Looks like it's been a while (first post was september 2007).
I joined the nvidia-bug-report.log and my tv EDID to this post, as I hope that may help the driver developers to find a workaround.
If anybody encounters the same problem, could you tell us because I think it's quite a common issue. There's an obvious workaround (buy a new card with hdmi output) but I hope nvidia developers would be kind enough to spare my purse and issue a patch