Is HDMI-> DVI INcompatible?

[Phantomguy]

From all my research it now appears that the promise by HDMI to be "fully backward compatible with DVI" is a broken promise! It appears that HDMI will NOT read the format of the Extended EDID table through the DVI ports pin 7 which carries "reply" data (DDC signal) as to the display device's format capabilities (eg 720 x 480 OR 1280 x 720 etc) which resides in the PROMS on the interface board of the DVI port in the display device, so the HDMI ICs dont see it (and it my case the HDMI sender wont supply 720p).

The DVI extended data is in a format defined long ago by VESA and the HDMI seeks to read extended blocks of the EDID table in a more recent format defined for CE. Why couldnt the logic in the HDMI ICs ID the display device as having a DVI port and then read the VESA format???

Truly, there has been NO/INSUFFICIENT effort by HDMI LLC to provide Plug and Play Compatibility with the millions(?) of DVI ported devices out there that are still too good to scrap. An alternative would have been for HDMI standards to proivide a manual (user) override/intervention to force a chosen format to be sent from the HDMI source device and/or intermediatory device (eg AV Receivers), but me thinks, too much arrogance on the part of HDMI LLC has "blinded" them to the need for a failsafe option.

For those interested I will shortly post two postings which I have made to OLD threads (which received no replies?) about my recent experiences in this area using Yammie RXV2600 and 2700 AVRs into my 1 year old BenQ PE8700+ Front DLP (and into other simlilar DVI ported projectors) using HDMI->DVI cabling.

I hope for a robust discussion on this issue in general so that pressure can be put on HDMI LLC and manufacturers of new HDMI equipment; and I also look forward to someone having solved or come up with a "workaround" to this problem as it relates to my own equipment.

 

[Phantomguy]

....(and it my case the HDMI sender wont supply 720p).

Fellow Audioholics, I guess I should have said "...wont supply 720p or 1080i options on the Yammie Upscaling GUI as are greyed out"

So as to be more exacting.

 

[Jedi2016]

Is this a problem with the TV or the output device?

'Cause I'm about to dump some money into a Westinghouse 1080p set, and the AH review mentions some issues with 1080p over HDMI. I was hoping that I could use a HDMI>DVI cable and use the DVI input instead... Hm. May have to think my cunning plan through some more. I'm still getting the TV, I'll just have to be pickier about the output devices, I suppose, make sure they have DVI outputs.

 

[Phantomguy]

Is this a problem with the TV or the output device?

'Cause I'm about to dump some money into a Westinghouse 1080p set, and the AH review mentions some issues with 1080p over HDMI. I was hoping that I could use a HDMI>DVI cable and use the DVI input instead... Hm. May have to think my cunning plan through some more. I'm still getting the TV, I'll just have to be pickier about the output devices, I suppose, make sure they have DVI outputs.

Jedi I think u may be miunderstanding the problem I posted . It is where the display device (TV or projector) has a DVI input port (and NO HDMI) and the sending device (source or intermediate device like upscaling AVR) ouputs HDMI. The HDMI seeks information from the display device about its capability and this is in a Basic and Extended EDID table stored on a PROM on the PCB behind the DVI port. The problem appears to be that the format for Extended table at the DVI end is VESA (PC) standard and the HDMI expects CE (Consumer Electronics) format, so it does NOT get all the info. Depending on how much it gets ... it may just not display, or give HDMI and HDCP errors, or supply a lower format that the display will support (that is my problem).

SO U WOULD BE WELL ADVISED TO AVOID DISPLAY DEVICE THAT HAVE DVI PORTS ... unless like me u already have the beast.

Unless HDMI change their own Firmware standards (and read the VESA format as well) then people like me are screwed .. they should because they did promise HDMI would be fully backward compatible to DVI. (Even Gene or was it Clint? believed this was the case when he said so in his expose on DVI and HDMI written in 2005).

PG

 

[Jedi2016]

I know what you're saying, I'm just boiling it down to the bottom line... HDMI>DVI doesn't work on your setup.

I only mentioned it because on the setup I'm putting together, I was planning to use HDMI>DVI on one of the components. And from what you're saying, that might not work, and would be a waste of a cable.