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Discussion Starter #1
Can anyone help. Here is my situation


I have a wall panel that accepts hdmi input from a laptop. Behind the wall there is 35' of hdmi cable that then plugs into a AV Receiver. The AVR then sends out to a ceiling projector.


The problem is that if I am sending video signal only (no audio) then the picture display perfectly on the projector attached to the AVR.


However, if my source has an audio signal in addition to the video then I get one of the following:

1) The picture is fine but there is no audio

2) The picture loses one of its primary colors (usually green) and the audio plays fine.


I don't get any sparkles or black spots. Its like the cable can only carry 3 primary signals and so either a video or audio signal is dropped.


The length of hdmi cable connecting the laptop to the wall port does not seem to matter as I have the same problem with an 6ft and a 16ft cable.


I recently purchased a booster for the 5v line to see if that would help and it made absolutely no difference.


I have read something about DCC but have no idea if that is the problem and if so how to fix it.


Any help would be greatly appreciated
 

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Exactly what models of equipment do you have? (display device, AVR, computer, graphics chipset, editing software).

People with experience with those particular products might have specific suggestions.


My guess would be that the problems you're seeing most likely are the results of buggy laptop software, HDMI drivers or firmware.


HDMI/HDCP interoperability is still a black art, and manufacturers are constantly making updates to support them better. Make sure you have up-to-date firmware in the projector and AVR, in addition to current versions of the BIOS, graphics drivers and software used in the computer.


For testing and initial development, I suggest using a 6-12 ft HDMI cable to connect the laptop directly to an inexpensive LCD TV. In addition to helping locate the source of the problems you're currently seeing, it would reduce the number of hours you burn on the projector's rather expensive illumination source. HD TVs are available for less than the cost of a new projector lamp.
 

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The first thing to do when the source is a computer is to make sure Deep Color is turned off.


FWIW your total cable length from the laptop to the AVR is in the range where problems start happening. How long is the cable from the AVR to the projector? What resolution and frame rate are you running? Are all the cables involved certified high speed?


The fact that you have a picture tends to indicate that this is not a HDCP problem. A color shift could mean one of the three TMDS data channels has a problem, or you are using the wrong color space.


FWIW transmission of sound and video over HDMI isn't an either/or situation. Audio is transmitted on the same TMDS channels as video, in between blocks of video. If you are not hearing audio, it either isn't there to start with, is encoded in a manner not supported by the AVR, or the AVR isn't configured properly.


I think I would look closely at the configuration of your laptop first. Doing what Selden suggested would be a good start.
 

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Discussion Starter #4
Thanks for the reply.


The equipment is as follows:


Laptop : HP Elitebook 8440 p, Intel Graphics is all it says I can't find a specific chip set

AVR - Pioneer VSX 921

Projector - Epson Powerlite S11

Editing Software - not using any.


I will try a different laptop and that will answer any questions if the problem resides there.


However I did test the configuration out before I installed it and with different cables (shorter) and no wall panel it worked fine. So I am thinking it may have more to do with the 35 ft line from the wall panel to the AVR. Those are the two new variables.
 

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Discussion Starter #5
Colm -


I don't know what you mean by deep color - Looks like I can set it to 32 or 16 bit. Currently it is 32 are you suggesting 16?


The Cable quality might be an issue the one from the wall plate to the AVR is smaller in diameter than the one going from the AVR to the Projector. By the way a DVD plays fine. With both video and audio so I think the cable from the AVR to the projector is not the issue. As to whether either is High Speed Certified I can not say.


Refresh rate is 60 Hz and Resolution is 1280 x720
 

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Deep color is an option in many HDMI-capable systems which includes the transmission of more than 8 bits per color channel. Since it adds more bits to the video transmission, it requires a higher-bitrate to be transmitted for every frame. Disabling it reduces the HDMI bandwidth requirement, allowing more reliable operation over longer cables.
 

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If your DVD player has an HDMI connection, another diagnostic would be to connect it to the long cable in place of the laptop.

If it looks OK, then the finger would point more firmly at the laptop.


Note that HDMI is only allowed to carry those video scanrates defined for consumer video. When connected to your AVR, your laptop should be generating a 720p signal.


You can find out exactly what video chipset is in your laptop by using the program GPU Caps Viewer. It's available for free at http://www.ozone3d.net/gpu_caps_viewer/


Quite a few people have reported bugs in the HDMI support provided by Intel's graphics chipsets, which may be your real problem. From what I've read, Nvidia's support seems to be the most robust, although many people have had good luck with AMD graphics hardware.
 

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Trying a different laptop will provide a good clue. Using the shorter cable at the HDTV with the original laptop would also provide another clue. Try to only change one variable at a time and then put that variable back to its original condition before trying another change.


As Colm said, one wya to generate this is to have non-matching color spaces. This would usually be someone accidentally set the color space parameter (or switch) to RGB.


Probably not a cable problem since 720p is standard speed and a complete consistent dropout of audio while full moving video is shown is not something I'd expect for a cable problem. Remember these are digital cables - you're passing 1s and 0s as voltages, not voltages that directly corresponds to a color or audio, as with component video and analog audio cables.
 

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At 720p, I don't think the cables are going to be the problem. Well, maybe. What the laptop sends is a function of the EDID information sent by the projector and the AVR. And although the video/audio data is transmitted using a fairly robust mechanism, the EDID information takes a path that is less robust. If the EDID information gets corrupted, I guess the wrong color space could be used by the laptop and maybe it might not send audio.


Are you using DisplayPort for HDMI? If so, are you using a passive or active HDMI adapter? There have been reports of problems with DisplayPort to HDMI connections on some gear.
 

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Lots of variables in your system - it's usually best to try and simplify the system to try and pin point your problem.


What signal formats are you sending to the AVR?


Is the AVR in bypass or video process mode?


Joe
 

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Discussion Starter #11
Thanks to all for the helpful hints. I will work on trying to implement some of these and let you know the results.


dan
 

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Discussion Starter #12
Just thought I would update everyone.

There was another variable in the equation that I stupidly forgot to include. It was a VGA to HDMI converter. I now believe that is the culprit.

I had a newer laptop connect via the VGA converter and the same issue occurred. This laptop however has hdmi out and so when we connected via that port then everything worked as it should.


Thanks for everyone's input
 

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Wow... a box all of sudden appeared ... :) That would certainly explain some of the "weirdness"... BUT I don't believe vga carries any audio so you had to send audio seperately from the video to the box and then have it "converted" into hdmi stream ... hmmm. I think you may still need to look a little closer at your setup and perhaps update your post with more info if you are still "blaming" the box.
 
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