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Audio static with DVI->HDMI cable?
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Author:  ceenvee703 [ Sat Apr 25, 2009 8:29 pm ]
Post subject:  Audio static with DVI->HDMI cable?

I had been running with my Biostar TF7025-M2 motherboard's onboard Nvidia GeForce 7205 graphics. I was using its DVI output and connecting to my HDTV with a simple DVI->HDMI cable and everything was fine.

Now, I'm trying to upgrade my system so I can start running R6 and VDPAU. I added a hard drive (see elsewhere) and a MSI GeForce 8400 GS 512MB video card.

I connected the existing DVI->HDMI cable to the video card, restarted--and heard incredibly annoying static from my TV speakers. It's as if the video signal had something new in it that the HDMI input was interpreting as audio.

Luckily, everything runs through my receiver, so I can work around the problem by just shutting off the TV speakers. But has anyone experienced this, or read about this kind of problem anywhere online? Know of a better solution?


Author:  tjc [ Sat Apr 25, 2009 11:53 pm ]
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I've had and discussed cross talk issues with the nest of cables behind my TV and other equipment in the past. The best solution seems to be good shielded cables. In the current setup the DVI - HDMI cable is the top model from monoprice with ferrite cores added at the ends, and all of the other cables use coax wire. Everything is also kept as short as possible (<= 6').

Good cables don't need to be expensive either. There are any number of on-line sources where you can buy a complete set of cables for less than the cost of just one at your mega electronics retailer.

Author:  jzigmyth [ Sun Apr 26, 2009 6:36 am ]
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ceenvee703, Does your tv have an hdmi input that has separate rca audio jacks associated with it? That is the input that I use on my tv (hdmi 4) and I have no audio problems using a 50 foot long hdmi cable with a dvi to hdmi adapter on the computer end. The cables were the cheap ones from monoprice, no ferite.

Video card FX5200 @ 1080p
not using VDPAU or XvMC
TV sony 46z4100

Author:  ceenvee703 [ Sun Apr 26, 2009 6:41 am ]
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Thanks for the ideas.

I don't see how it could be interference since I hear it with the new video card and not with the on-board video--the cable itself is still next to all the other sources of potential interference. It's also not intermittent or faint, it's really loud.

I use Monoprice cables as well--they're great. Not sure if they have the ferrite things or not, will check.

I think I have a separate audio input for the VGA input only, but I'm using that input for my Xbox 360. I'll double-check though.

Author:  graysky [ Sun Apr 26, 2009 6:46 am ]
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If I'm understanding your setup right:

Old setup
-Old setup uses onboard video via DVI-->HDMI
-Audio is via RCA cable (8mm on end and L/R audio other end)
-This old setup works fine, no static

Am I right?

Author:  ceenvee703 [ Sun Apr 26, 2009 6:58 am ]
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Hey, what are you doing on so early? :)

No, both old and new setups were using digital audio directly to the receiver. At first I thought the static was coming from the receiver, but then realized it was coming from the TV speakers, hence my thought that somehow the new video card was sending something else down the DVI cable that the HDMI input was interpreting as audio.

I realized that I didn't have to have the TV speakers on since all my audio goes through my receiver, so it was an OK workaround. Just curious about the difference, basically.

Author:  graysky [ Sun Apr 26, 2009 9:08 am ]
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I'm still confused as to how you can go from DVI-->HDMI and have any audio signals.

Author:  ceenvee703 [ Sun Apr 26, 2009 9:59 am ]
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I didn't understand it either, hence my throwing it out there. Particularly didn't understand it since the motherboard DVI output doesn't give me the static.

Also, maybe "static" isn't the best word to describe it... it's fast, loud popping, almost like a Geiger counter.

Author:  tjc [ Sun Apr 26, 2009 10:04 am ]
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graysky wrote:
I'm still confused as to how you can go from DVI-->HDMI and have any audio signals.

That's just it, you're not supposed to, but since straight HDMI also carries audio signals, anything it picks up on the wire might cause static.

Here are a couple things to try.

1) Does the static vary based on what is on the screen? For example blank screens versus ones with a lot of pattern (vertical stripes or checkerboard). This would almost certainly indicate interference from the video signal.

2) Since the on board video doesn't have any static, try to think of or see how else they might be different. Grounding, drive voltage, difference in the connectors, ...

Author:  ceenvee703 [ Sun Apr 26, 2009 12:54 pm ]
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I'll think about #2.

As for #1, no, it doesn't seem to be affected by what is on screen (at least comparing a MythTV menu to a video being played back).

Author:  goofee [ Sun Apr 26, 2009 4:03 pm ]
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I was reading up on this card before.
Part way down the page it talks about feeding audio from the sound card to the video card to output audio/video on one HDMI cable. Is it adding interferance at that point?

HDMI with Audio Integration Solution
The NVIDIA® GeForce® 9 Series graphics card supports HDMI with audio integration solution. With a DVI-to-HDMI adapter and an extra signal cord through the bracket, audio source from sound card(S/PDIF) can be integrated into HDMI interface by simply plugging the cord into the pinhead located on graphics card. Only 1 single HDMI cable is required while streaming audio/video data to flat-panel display devices, such as Plasma/LCD TVs, or projector.

Author:  tjc [ Sun Apr 26, 2009 9:08 pm ]
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and an extra signal cord through the bracket ... plugging the cord into the pinhead located on graphics card

This might very well be the source of your interference. Especially if it's a bare pin header. Those can make pretty good antennas. You might have to make this connection to keep it from introducing random noise. Especially if you're using their special adapter and an HDMI-HDMI cable rather than a regular DVI-HDMI cable.

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