Originally Posted by mpgxsvcd
I am not sure I understand enough about the EDID value to make a definitive statement about it. Could you do a statement about it that says us "exactly" what the EDID is telling us?
I'm not the EDID expert here (learnt everything from reading and from our very own Archibael) however, I'll have a go for you and if Archi is watching he can add to it.
Any HDMI compliant sink must advertise an EDID version 3 extension block. The presence of the extension block is confirmed in the standard EDID block by byte 126 (counting the first byte as zero). If this byte is "01" this indicates that an extension block is present.
A version 3 extension block contains several bits of information specific to an HDMI sink. The first is the Vendor Specific Data Block (VSDB). This can contain anything a vendor considers important but MUST be populated for a device to be considered HDMI compliant. The other data which I would consider important to this issue is the Short Audio Descriptors (SADs) which are also contained within the 1.3 extension block. These 3-byte identifiers "describe" the audio formats supported by the sink. Futher informatin can be found at http://en.wikipedia.org/wiki/EDID
The bottom line is that unless the 1.3 extension block is correctly identified and read, the source does not know if a sink is HDMI or not and even if there is an "assumption" of HDMI compliance, there is no way of knowing the audio capabilities of the sink.
Exactly why the ATI drivers are repeating the first EDID block rather than parsing the correct extension block I have no idea but the reports I've seen suggest this may be why we're seeing the problems with people unable to get audio working and why some HDMI devices are incorrectly identified as DVI.
Like I said, this is a rather large and complex topic which I try to "sanitise" in my mind to retain a basic understanding without constantly checking documents. Also, my involvement in this was initially related to DTD's (Detailed Timing Descriptors) rather than audio capabilities and again only to pass on "enough" information for someone else to work with.
Hope this helps but if not please feel free to say so and I'll try and explain things dfferently or maybe get an expert to comment.