Advice on how to fix an invalid EDID on projector
Evening all, Sorry if this should have gone to LUV-Main instead. I'm not sure how Linux related it will end up being. I'm looking for a little direction on an issue with an Acer P1266 projector which won't work with PC devices plugged in using HDMI. My knowledge of HDMI and all of its standards and uses is very limited but I understand I should be able to plug in a PC and have it just work. The issue is that the projector will just sit on HDMI without attempting to mode set when a computer is plugged in. I was under the impression that the HDMI port was just broken until fiddling with the HDMI caused it to set a mode once or twice. What it set was something unexpected like 480x360 48.36 hz @ 85 and after reading the available modes for HDMI in the projector manual I found this was not one of them. Remembering something about EDID information I thought that the port might not be broken and that something else might be happening. Windows and Lion have woeful verbosity when things break so I got out a trusty Ubuntu computer and hooked it up to the projector to see what it could see. Here is what I found in the Xorg.0.log http://pastebin.com/iXU86awD (note I fixed the Validated Modes being wrong resolution and device after taking this log). The Nvidia manual allowed me to remove the first clear issue which is the conflict with Horizontal Sync in Xorg like so... Section "Monitor" ... HorizSync 15.0 - 50.0 # a guess based on xorg log output Option "UseEdidFreqs" "false" EndSection This cleared up all errors except... [ 19.896] (WW) NVIDIA(0): ACER P1266 (DFP-0)'s EDID does not contain a maximum image [ 19.896] (WW) NVIDIA(0): size; cannot compute DPI from ACER P1266 (DFP-0)'s EDID. [ 19.896] (==) NVIDIA(0): DPI set to (75, 75); computed from built-in default So I started reading into what EDIDs are and how to do anything with them. First priority seemed to be to get a copy and then work out how to fix this issue. Enter what I found when I output the EDID and parsed it http://pastebin.com/EtNtArfk I think this maybe the time to ask for some advice from some people who may have come across this before. The net gives me some suggestions but I've got no idea what to look into... * Continuing to look at how to modify the EDID that is there to set a maximum image size and load that EDID on the projector * Looking at taking the information I do have from the EDID and making an xorg conf that uses that * Not trusting the EDID source as advised by parse-edid Some extra notes: * The projector is out of warranty and Acer have never put out any updates for it. It was never very popular so it's entirely possible no one ever bothered fixing this issue. * Xorg.conf is totally stock standard with nothing strange apart from the above, I can include a copy if someone wishes to see it. * Xorg.0.log is totally normal beyond what's included in the above paste bin, I can include a copy of the entire thing if required. * I don't have any video devices that output to HDMI to test with as I believe this sends a separate EDID? * The PC devices can drive projector using analog connections. [1] http://pastebin.com/iXU86awD subset of xorg.0.log with stock standard xorg.conf [2] http://pastebin.com/EtNtArfk output of get-edid | parse-edid Thanks in advance if anyone has any experience with this, Edward
On 12/11/11 22:15, Edward Savage wrote:
Evening all,
Sorry if this should have gone to LUV-Main instead. I'm not sure how Linux related it will end up being.
I'm looking for a little direction on an issue with an Acer P1266 projector which won't work with PC devices plugged in using HDMI. My knowledge of HDMI and all of its standards and uses is very limited but I understand I should be able to plug in a PC and have it just work.
The issue is that the projector will just sit on HDMI without attempting to mode set when a computer is plugged in. I was under the impression that the HDMI port was just broken until fiddling with the HDMI caused it to set a mode once or twice. What it set was something unexpected like 480x360 48.36 hz @ 85 and after reading the available modes for HDMI in the projector manual I found this was not one of them.
Just to be sure - you plugged the projector into the PC before powering up the PC? Most motherboard based HDMI/DVI ports only operate if they find a display device on boot up. This includes laptops with "graphics cards". Normal graphic cards happily spit out VGA and DVI together.
On Sat, 12 Nov 2011, Edward Savage <epssyis@gmail.com> wrote:
* The PC devices can drive projector using analog connections.
If it works on VGA then what is the benefit in HDMI? Projectors don't tend to have high resolution, particularly ones that are old enough to be out of warranty. I was under the impression that quality at high resolution was the main benefit that people get from using HDMI? From my own experience using projectors it seems very rare to have any quality problems that aren't directly related to low resolution, poor focus, ambient light, or a poor projection surface. As an aside I've finally got DVI working. After years of using VGA to drive monitors which are DVI capable and a couple of months of owning a monitor which can only be driven at full resolution with DVI or HDMI I have finally bought a video card that has DVI (I got the silent 5450 - thanks Craig and others). It took me a couple of months because 2048*something on my 2560*1440 monitor looked so much better than anything I'd experienced that I didn't feel an immediate need to make it even better. As an aside, I've seen adverts for a digital video camera with a built in projector. Has anyone tried one of them? Obviously such a projector wouldn't compare to the quality you get from something attached to the ceiling. But I was wondering if you could put a VGA resolution video on one of those and project it such that text is readable. Technically it shouldn't be that difficult to make a VGA resolution video of lecture slides and then use pause/play to control moving between slides. This could be used as a backup for when we have problems with something like a LUV meeting and also for informal talks. -- My Main Blog http://etbe.coker.com.au/ My Documents Blog http://doc.coker.com.au/
On Sat, Nov 12, 2011 at 10:47 PM, Russell Coker <russell@coker.com.au> wrote:
On Sat, 12 Nov 2011, Edward Savage <epssyis@gmail.com> wrote:
* The PC devices can drive projector using analog connections.
If it works on VGA then what is the benefit in HDMI? Projectors don't tend to have high resolution, particularly ones that are old enough to be out of warranty. I was under the impression that quality at high resolution was the main benefit that people get from using HDMI? From my own experience using projectors it seems very rare to have any quality problems that aren't directly related to low resolution, poor focus, ambient light, or a poor projection surface.
I have an Apple TV that I wish to run Plex via and the Apple TV will only output a digital signal to either DVI or HDMI (I believe this ends up being the same). I expect that if I can fix the EDID it will do this. The projector will output 1080p or some attempt at it though I will be more than happy with 720p. I did buy the projector with the expectation of being able to use HDMI so I do feel ripped off if this is in-fact a manufacturing fault. Allan I have tried various combinations including several voodoo solutions from the web (with no expectation that they would work). This includes the orders of startup for the projector and device attached. No luck. Regards, Edward
participants (3)
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Allan Duncan -
Edward Savage -
Russell Coker