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GTX 460/570/580 - simultaneous audio and 4:4:4 chroma from HDMI port?

Jan 18, 2011
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Updated: GTX 460/570/580 - simultaneous audio and 4:4:4 chroma from HDMI port problem

Hello, first-time poster. This forum comes highly recommended from a friend of mine for my somewhat technical concern :)

I currently have an AMD 5850. It's the first time I've used a non-nvidia card since my Voodoo 3. I regret jumping ship :/

My setup requires I output HDMI audio and Full RGB or YCC 4:4:4 video to my receiver and then pass it along to my 4:4:4 display. With my 5850, I can only output subsampled chroma (RGB Limited or YCC 4:2:2) from the HDMI port of my video card while simultaneously outputting HDMI audio. The only way I can get 4:4:4 chroma out of my 5850's HDMI port is to hack my display or receiver's EDID and disable HDMI audio. Behavior is the same if I go through my receiver or straight to my display. Using the DVI port with a DVI to HDMI cable to my receiver or straight to my display works fine, but then I'm missing out on 8-channel PCM and bitstreaming, defeating the point of my receiver and surround setup. I'm not willing to return to SPDIF.

TL;DR: Basically, I'm looking for confirmed reports of users getting 4:4:4 chroma (either YCC 4:4:4 or RGB Full) from their 460 (or 570/80) GTX via the HDMI port while simultaneously passing audio along HDMI.

After reading a single report from someone who says he suffers the same problem I suffer on my 5850 on his 460 GTX, I'm worried this is an inherent HDMI limitation. However, if so, it's undocumented.

If you're unsure and you have an HDMI to HDMI connection on your 460/570/580 and send the video/audio signal to an HDMI audio-enabled device (be it a TV or an AVR of spec 1.3 or beyond), please confirm you're getting proper 4:4:4 chroma sampling by taking a photo of the test image here:


See if you get straight red pixels, or a multi-colored mess from your close-up photo of the section to the left of the "20". For comparison, here are my photos. The first is proper 4:4:4 taken of my 5850 outputting to my display (or through my AVR, makes no difference) via a DVI to HDMI cable.

The second photo is subsampled 4:2:2, my only option when outputting straight HDMI to HDMI with audio, either to my receiver or to my display:

Thanks so much to anyone who can give me a definitive answer as to if the 460 will output proper 4:4:4 chroma whilst passing audio. The HTPC crowd largely doesn't care about this, because they mostly watch Bluray discs on their PC. I'm a gamer and regular desktop user, so subsampled chroma is blindingly obvious to me. I also don't want to fall back on SPDIF for audio as ATI users in my position must do. I'm ready to make the jump back to Nvidia, but need a little proof first. Thanks for reading.

Edit: Please note a lot of TVs subsample all chroma to 4:2:2. Make sure yours supports 4:4:4 before trying the test!

Edited again:

I've reached a conclusion on the downsampled chroma issue. It affects not only AMD users but Nvidia users as well, and is either a fundamental hardware problem with the HDMI interfaces that AMD's 4xxx/5xxx/6xxx line and nvidia's 4xx/5xx lines (the ones with integrated HDMI audio codecs) use, or a problem with the middleware libraries both companies' drivers make calls to. The problem has existed since 2009, has never been acknowledged by developers at either company, and probably won't be fixed anytime soon.

Basically, whenever video in addition to audio is passed from the HDMI ports of either vendors' cards with integrated audio codecs, chroma is subsampled to 4:2:2 no matter what. I urge anyone using the HDMI port of their card to output video AND audio to their AVR or HDMI audio-capable display to take the test I outlined above, or for an easier method, just look at the image below:


If the words "Red" and "Magenta" appear fuzzy and nearly illegible, your card is afflicted with the problem.

You can read more about this problem at this thread (and the ones linked within it) at AMD's forum and this thread at AVSForum, starting around post #800. I realize the latter thread is specific to a single TV, as are many of the examples, but this is because this TV is one of the few to support Full RGB and Full YCbCr 4:4:4 pixel formats and has become very popular among the multi-use display crowd--the problem afflicts all displays indiscriminately provided the display is 4:4:4 capable and the signal path to it is as outlined above. Please note that if you're using a DVI to HDMI cable to connect to an AVR or display, you won't be affected by this problem.

Thanks for reading! I want to bring as much attention to this problem as possible. It's my hope that if enough people are aware of this problem, either future hardware revisions will have HDMI interfaces with proper HDMI 1.3+ output, or the middleware libraries both vendors depend on will eventually be fixed and allow for proper chroma along with 8-channel PCM/bit-streaming.
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