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Lumagen HDP EDID Pass through


Standard Member

Could anyone answer a couple of EDID questions with the Lumagen please.

a) I assume that even with pass through set config->dvi->edid = pass, that there will be no audio advertised even if the device that is being copied has audio capability in the EDID ?

For example, I am using a CLUX-14S 1:4 HDI splitter on the output of the Lumagen. This device simulated EDID is saying it has audio, but the Lumagen input says it does not support audio. This makes sense, but just want to check since I am splitting the output from a blu ray player into the amplifier (Onkyo 875) and the Lumagen. When the amp alone is connected I get full audio 7.1, master HD, true HD etc, when I add the Lumagen I get PCM.

I understand that the blu ray player will find the lowest common denominator and hence the PCM. I can use a splitter with EDID simulation instead and that should isolate the Lumagen from the Blu ray, but I just wondered if I was missing something and could avoid shelling out for another splitter.

b) Looking at the EDID from the Lumagen, Is there a "hangover" from earlier EDID settings when you use pass through?

For example,

1) I set user setting with YCbCr 444 and 422 set to no.
2) Switched to pass on the Lumagen.

The Lumagen input gave an EDID with these set as not supported.

3) Switched back to user and set YCbCr 444 and 422 set to yes.
4) Switched to pass.

The Lumagen input gave an EDID with these set as supported. It looks as if the pass through EDID was still being overriden by the previous user setting.

Any answer very much appreciated and sorry for the long post.



Distinguished Member
One thing with EDID is that it can be important to power-cycle everything. Switch everything off, unplug everything from the mains, then switch the HDP on, wait till it's fully booted up, then switch on the source. That way you'll definitely be rid of any "cached" settings.


Standard Member

That did clear the extra data. This does open up another question though, is it possible that the Lumagen is only passing through the standard EDID 1.1 data. This would explain why additional info in the 1.2/1.3 data is being left hanging around.

Byte 1-127 + checksum
Version 1 (as defined in -861) allowed the specification of video timings only through the use of 18-byte Detailed Timing Descriptors (as detailed in EDID 1.1 data format above). In all cases, the "preferred" timing should be the first DTD listed in a CEA EDID Timing Extension.

Bytes 129 onwards

Version 2 (as defined in -861A) added the capability to designate a number of DTDs as "native" and also included some "basic discovery" functionality for whether the display device contains support for "basic audio", YCbCr pixel formats, and underscan.
Per Version 3 (from the -861B spec), there are two different ways to specify the timings of available DTV formats: via the use of 18-byte Detailed Timing Descriptors as in Version 1 & 2, and via the use of the Short Video Descriptor (see below).

When the Lumagen is power cycled with pass thorugh the EDID is only 128 bytes long. The 1.2 and 1.3 data is missing. When the Lumagen is power cycled with user, the extra EDID info is present, being generated by the Lumagen. This explains why the additional info is not being overwritten.

Testing with a couple of displays and amps seems to support this.


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