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Discussion Starter · #1 ·
Hello everyone, my HTPC is hooked up to a Yamaha RX-V471 AV receiver with an HDMI cable (I'll call it "Cable 1"), and the receiver is in turn hooked up to a Sony Brava LCD TV with another HDMI cable ("Cable 2"). Sometimes the screen intermittently goes black for a fraction of second, which is not unlike this problem discussed in another thread . I'll quote the OP from said thread to describe my problem:

Black out is only momentary. Picture comes back quickly. When this condition occurs, it could happen between 4 times in a minute and a couple times in an hour or so.


Only the video signal is affected: the audio signal is fine. This only happens with the signal sent from the HTPC via Cable 1. I haven't had the chance to try hooking up other devices to the receiver, but if I watch TV channels there are no black flashes.


There are several things that can trigger the problem, but there's a situation I've experienced particularly often: black flashes after resolution changes, e.g. when I run a fullscreen application in 720p while the desktop resolution is 1080p. To make the flashes stop, I need to turn off the receiver for about 10 minutes. If I turn it back on sooner, I get black flashes again.


Do you have any ideas who the culprit could be? I'm suspecting a flaw in the receiver, but I'd like to get your opinions.


A couple more details:

- HTPC's video card (hooked up to receiver via Cable 1): Sapphire Radeon HD 7770. It used to have a Radeon HD 5450 and the same problem happened too.

- I used to hook up the PC directly to the TV with Cable 1. I never had this problem back then, even after resolution changes.


Thanks in advance!


edit: Additional info:

- The TV's firmware and the video card drivers are up-to-date. There is no firmware update for the receiver as far as I know.

- Both Cable 1 and Cable 2 are High Speed HDMI 1.3 cables. Cable 1 is 1.5m long and Cable 2 is 5m long.

- The black flashes don't occur at all resolutions. It definitely occurs at 1080p, i.e. the TV's native resolution, regardless of the application (e.g. fullscreen 1080p game, desktop etc.). It doesn't seem to occur at 720p, so if I run a fullscreen 720p application I'll only get black flashes when I return to the desktop. It's not very easy to test because sometimes after a resolution change a couple of hours can go by without any flashes occuring and then the problem appears.
 

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Not enough information to give you a definitive answer. So..


1) Do you have the latest firmware in the TV and the receiver?

2) Are you using the latest video card drivers?

3) What type of cables (High Speed or Standard Speed) and how long are they?


Obviously the only way you are going to really know is to try the substitution game. Try a different TV (even if you have to borrow one). Try a different receiver. Try different cables. Try a different HTPC. Unfortunately even then you could still be having an interface problem where replacing either side of the interface bypasses the problem. Both sides are correct but when put together they are incompatible (even though that shouldn't happen with HDMI).


If I had to guess, I'd say you either have bit errors in the stream or incompatible firmware/drivers. But, you didn't provide enough information for anything other than an educated guess.
 

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First test would be to bypass the AVR – power everything Off at the wall, connect the HTPC direct to the Display then repower and run everything to way you normally would (don’t make any changes to the HTPC) – do you get the same glitches?


Joe
 

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Joe's test is a good one. The only thing I'd add is to only use the 5m cable (cable #2) during the test. I suspect that is where your problem lies. That everything at 720p works is a good clue that this is possibly a bit error problem. The intermittent nature of the problem is also another possible clue.


BTW, there are no such things as HDMI 1.3 cables. Only standard speed and high speed. The cable doesn't know which version of HDMI is being used.


After you get done with Joe's test, could you verify that all of your sources work without problems at a resolution of 720p? If that is true, I think replacing your 5m cable with a new certified high speed cable may be your best bet for solving the problem.
 

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Discussion Starter · #6 ·

Quote:
Originally Posted by alk3997  /t/1469253/black-flashes-with-resolution-change#post_23230720


After you get done with Joe's test, could you verify that all of your sources work without problems at a resolution of 720p?
Sorry, I'm not quite sure what you mean. Are you talking about testing other devices hooked up to the receiver?


Anyway, I've tried hooking up the PC directly to the TV with the 5-meter Cable 2 without involving the receiver, as Joe Fernand suggested. I changed the resolution from 1080p to 720p and reverted the change a few times to increase the chance of black flashes occurring. Then I used the PC for several hours (at 1080p), and the problem didn't appear.


Another simple thing I haven't tried yet is connect Cable 1 to another HDMI port on the receiver. I'll do that as soon as I can and post the results.
 

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Quote:
Originally Posted by waca  /t/1469253/black-flashes-with-resolution-change#post_23234900


Sorry, I'm not quite sure what you mean. Are you talking about testing other devices hooked up to the receiver?


Anyway, I've tried hooking up the PC directly to the TV with the 5-meter Cable 2 without involving the receiver, as Joe Fernand suggested. I changed the resolution from 1080p to 720p and reverted the change a few times to increase the chance of black flashes occurring. Then I used the PC for several hours (at 1080p), and the problem didn't appear.


Another simple thing I haven't tried yet is connect Cable 1 to another HDMI port on the receiver. I'll do that as soon as I can and post the results.

Yes, basically what I was saying is to try as many devices at 720p as you can.


Your test would suggest that this is an interface problem or possibly that the 5m cable is "on the edge" of bit errors and the cable eq changes enough with the AVR to send it over the edge. Just because it is cheaper, I'd try a different 5m High Speed cable before doing anything else.


Also disabled "deep color" on your TV and on any sources if it is available. That will decrease the bandwidth requirements and make you less suceptible to bit errors.
 

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Discussion Starter · #8 ·
Well, it looks like I don't need to test anything anymore. Connecting Cable 1 to another HDMI port on the receiver seemed to do the trick.


Thanks again Joe Fernand and alk3997 for your help!
 

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Discussion Starter · #10 ·
Just a small heads-up: using another HDMI port did not solve all problems. Now I sometimes experience intermittent audio cuts, which seems to be the exact same problem discussed here . The video signal is fine, so it's pretty much the opposite of the problem I used to have before switching HDMI ports.


I haven't figured out what triggers those audio cuts, but I might have found a way to alleviate the problem. I'm posting it here since it might be useful to other people too:


1. When the audio problem appears, change the HDMI input that is currently used by the receiver with the remote, e.g. if the input called "HDMI 2" corresponds to your HTPC (or Blu-Ray player etc.), you can change the input in use to "HDMI 3".

2. Unplug the HDMI cable from the receiver and plug it back into yet another port. If the HTPC is hooked up to the HDMI 2 port, plug the cable into the HDMI 4 port.

3. Use the remote to select the new correct HDMI input, i.e. HDMI 4. You shouldn't have any audio signal losses now.

5. The audio problem is not limited to one particular HDMI port (unlike the video problem I used to have), so if it happens again, repeat the process.


There's a caveat: when you switch to the new HDMI input with the remote, you may not recover the audio signal and have no sound at all. Rebooting the PC might get everything to work perfectly without audio cuts.


In the end it's still a fairly annoying problem, but I guess I can live with that.
 

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Quote:
Originally Posted by waca  /t/1469253/black-flashes-with-resolution-change#post_23426454


Just a small heads-up: using another HDMI port did not solve all problems. Now I sometimes experience intermittent audio cuts, which seems to be the exact same problem discussed here . The video signal is fine, so it's pretty much the opposite of the problem I used to have before switching HDMI ports.


I haven't figured out what triggers those audio cuts, but I might have found a way to alleviate the problem. I'm posting it here since it might be useful to other people too:


1. When the audio problem appears, change the HDMI input that is currently used by the receiver with the remote, e.g. if the input called "HDMI 2" corresponds to your HTPC (or Blu-Ray player etc.), you can change the input in use to "HDMI 3".

2. Unplug the HDMI cable from the receiver and plug it back into yet another port. If the HTPC is hooked up to the HDMI 2 port, plug the cable into the HDMI 4 port.

3. Use the remote to select the new correct HDMI input, i.e. HDMI 4. You shouldn't have any audio signal losses now.

5. The audio problem is not limited to one particular HDMI port (unlike the video problem I used to have), so if it happens again, repeat the process.


There's a caveat: when you switch to the new HDMI input with the remote, you may not recover the audio signal and have no sound at all. Rebooting the PC might get everything to work perfectly without audio cuts.


In the end it's still a fairly annoying problem, but I guess I can live with that.

So (from reading the other thread) it's a firmware issue with the Yamaha AVR. You should make sure you phone their tech support people so they can keep track of how many firmware issues they are having with that particular model. It is amazing how many times people (not you) hit these types of problems and then don't bother to call tech support.


Usually firmware problems with AVRs are handled by the engineers in their priority order. The more who people call, the higher the priority becomes , even if others have already reported the issue (which the call center will deny - you're the first to report this, sir).
 

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Discussion Starter · #13 ·
I haven't got around to calling tech support yet because of my chronic procrastination, but I've found out something rather odd about my audio problem. I only seem to lose the audio signal when I'm not running a fullscreen application! The other day I was running a fullscreen game and didn't have any audio probems. At some point I pressed Alt+Enter to make said game go into windowed mode, and the audio problem occurred. When I went back into fullscreen mode, everything was fine again.


Note that by fullscreen I mean 'real' fullscreen, i.e. not a fullscreen window (in this case a 1920x1080 window). I found that out by a running a test with XBMC, which can use either a fullscreen window or real fullscreen. After I quit the aforementioned game, I played a video in XBMC with the 1920x1080 window setting. There were audio cuts. I tried again in complete fullscreen mode and there was no problem.


Does that make any sense?
 
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