Random noise from HDMI

[sochee]

Reposted from http://forums.anandtech.com/showthread.php?t=2376513:

My AV chain is currently like this:

Nvidia 780Ti -> HDMI -> Panasonic TC-P42S60 -> SPDIF out to EMU 0404 USB -> RCA to amp

My problem with this is that when playing anything through the TV (mp3, flac, movies, etc.), there is a small static noise every few seconds, almost rhythmic. Yet, when I change the Nvidia 780Ti to a Macbook (keeping every other part of the chain identical, even the HDMI cable used), the sound goes away with the exact same source files. So I'm convinced this has something to do with the 780Ti output, but I haven't been able to find anything anywhere on why this might be. Any ideas where to start looking?

Something like this can't be caused by an HDMI cable right, since it is digital? Disappointed that my Macbook with cheap integrated Intel GPU can do HDMI cleaner than a $700 dedicated card.

 

[Automaticman]

No I wouldn't think this would be caused by a cable.

One thing to bear in mind is that it might not actually be related to the 780Ti itself. I could see something like this possibly being caused by some faulty RAM, something eating up CPU cycles in the background (you didn't say what the rest of your system is), a driver issue, or a problem with that particular player software, maybe even a HDD issue.

First thing I'd try, if you haven't already, is try playing the files using several different pieces of playback software (MPC-HC, VLC, WMP/WMC) and see if they all do the same thing. Monitor CPU and RAM usage to see if anything is maxing out. Try moving the affected files from a mechanical HDD to a SSD.

The Macbook effectively rules out the rest of your signal chain, but introduces so many variables at teh same time that it is difficult to use it to troubleshoot the problem any deeper than you have.

 

[sochee]

Ok, you make some good points, I have a hunch it has to do with the Nvidia drivers, and was wondering if anyone had the same experience. I am not knowledgeable enough about HDMI or A/V to figure this out. But, to cover your other points:

* 16GB ram and quadcore CPU, I did look at task manager briefly and everything is running smoothly, MemTest86 runs fine too
* Problem persists with HDD and SSD
* Problem persists playing FLAC/MP3 in Foobar2000 or MKV/AVI in VLC. Same exact noise, which makes me thing it's driver/hardware related.

Someone mentioned uninstall Nvidia drivers and letting Windows manage the HDMI output - would this be a good idea? Something tells me not really.

 

[Automaticman]

Have you tried changing the output settings in the audio properties for the HDMI output? Specifically the bit rate and sampling rate?

When it comes to HDMI audio, all of my experience is with AMD. I'm not sure how Nvidia implemented the feature, I know AMD essentially added a small Realtek chip onto the board, that works in conjunction with main Realtek chip on the mobo using the main onboard audio driver. The HDMI just shows up as an additional output in the Realtek driver.

In their case, using the HD audio and HDMI driver from the Realtek site is usually much newer than what is distributed with the AMD video driver, but I have no idea if Nvidia came up with something completely proprietary or not.

You could try letting windows install the driver, at least as a testing measure. It depends you can uninstall the HDMI driver while leaving the main video driver installed. I certainly wouldn't want to use a windows driver for video on a permanent basis, but I could see it being useful for troubleshooting. I mean, if the problem goes away, it will really narrow it down to a driver issue (of course, if the problem persists, it won't actually rule out it still being a driver issue)

 

[sochee]

I have tried the sampling rate, that was one of the first things I thought of. The weird thing is that this is cyclical - it repeats at regular intervals. And varies with the volume - if I'm playing something soft I'll hear soft crackles, and vice versa.

 

[sochee]

I'm an idiot - went back to the Macbook again just to be sure (has been a while since I tested it), and the crackling is there too. Checked the amp using purely analog input, and checked the EMU DAC with another digital source, both showed no crackling, so I'm guessing it has to do something with the TV's digital out, which is coincidentally the newest part of my chain. Sorry for wasting everyone's time.

 

[Automaticman]

Haha, no problem. Just goes to show that sometimes it is worth it to go back over items you were previously sure you had ruled out.

Check your TV's manufacturer page to see if it has had a software update that you can apply using a usb stick.

*edit*
It looks like the newest TV software is v2.211 from http://shop.panasonic.com/shop/model/TC-P42S60?t=downloads&support#tabs

Does your motherboard have an SPDIF output that you can connect directly to the DAC and bypass the TV/video card entirely?