I have a Soyo MT-SYTPT 4227ab LCD TV and a Toshiba Satellite A300 PSAG8C-048013 laptop (Windows 7).
When I connect them via HDMI, my laptop's HDMI audio device is specified as "not plugged in" and the TV does not output audio. When I connect my laptop to other TVs, my laptop's HDMI audio device specifies the name of the TV and the TV outputs audio.
I tried installing the latest video and audio drivers but the problem remains.
Previously my Xbox 360 also had this problem. I found this thread http://forums.xbox-scene.com/index.php?showtopic=631109
which describes a problem in which the Xbox 360 is not getting the proper handshake from the TV so it defaults to DVI output (no sound). I was able to disable display detection and my sound started working.
I also have a Patriot media box, which I tried with this TV, it outputs HDMI audio with no issue.
I booted into Ubuntu with a live CD and HDMI audio worked immediately.
All of the above led me to believe my TV is not sending the proper HDMI handshake so Windows is not outputting audio through the HDMI port. I downloaded a program called MonInfo http://entechtaiwan.com/util/moninfo.shtm
which gives detailed monitor information.
When I used it to check out my TV, sure enough, I found that my TV was not sending the EDID block specifying audio capability. See the differences in output between the Soyo TV and another TV.
soyo-moninfo.txt 3k .txt file
toshiba-moninfo.txt 5k .txt file
I did some research and found that people have been using this program to output INF files which they modify to enable HDMI audio.
1. Used a program called APx500 to generate an EDID extension block with basic audio information.
2. Loaded this EDID into MonInfo and generated an INF file.
3. Copied the extension block from the generated INF file into my TV's INF file.
4. Updated the driver for the generic PnP monitor corresponding to my TV with the INF file.
I still cannot get HDMI audio to work! Can anyone help me out?
custom.inf.txt 3k .txt file
custom-moninfo.txt 4k .txt file
Thanks in advance.