AMD R600 technology, yet again - T'n'T - 3
Author: Hrvoje Jakovac
Date: 04 May 2007

This audio-chip thingy deserves a special treatment in our article, for various reasons. Vista Premium Logo actually demands the following - to have the audio path that's completely integrated and HDCP-protected. We're not here to go into in-depth discussion about our way of thinking about Vista and HDCP, but there are some interesting features coming out of it. The basic one is to have video and audio through HDMI connector, which is really cool. No need to have a whole bunch of cables doing practically the same thing when you can do all of that with just one cable. Radeon HD 2000 series also has a special active DVI-to-HDMI adapter that you can use to carry audio data as well, which is a neat feature. The usual DVI-to-HDMI adapters can't do this. This adapter is also compatible with the usual DVI outputs so you can do DVI-to-HDMI on regular cards without the sound part, as well. As far as the basic audio data is concerned, the built-in chip supports 32kHz, 44.1kHz and 48kHz 16-bit output. For XP, you have the AMD's driver and for Vista, Microsoft's UAA driver. When I actually checked and gathered all I could find about R600 there was just one question mark over my head. From what I could find out, there's no 24-bit support for 96kHz or 192kHz audio, which is both good and bad at the same time. Let me elaborate this thought.

Imagine the following situation - you're watching a movie and you have your nice plasma TV with a DVD player and 5.1 surround system. Pretty cool when you're watching a movie, right? Almost pointless in games, mostly extremely unusable when you're watching a concert. And unbeliveably unusable when you're listening to your own Audio CD or MP3 collection. If you do some kind of surround emulation, you end up hearing something that has almost nothing to do with the original sound. But what we're talking about here are actually movies, so probably the only situation where you'll actually use your 5.1 sound system. Before someone throws a hard object to my head and starts yelling "YESSS, BUT XYZ CONCERT BY ARTIST 'W' SOUNDS SO AMAZING IN 5.1", I will actually make my point right now. I'm a huge DVD fan, especially concerts since I'm a musician, and so far I came across only about two or three concert DVD's out there that actually sound good in 5.1 surround. And don't even get me started on classical music and/or jazz, that would be a pretty pointless discussion. If anyone wants to flame about this one or anything related to R600, feel free to join us on our forum. Back to our point - HD-DVD movies. For HD-DVD playback, you must have TrueHD support (it's mandatory) while it's optional for Blu-Ray. What I was actually thinking was this - ok, R(V)6xx cards don't have 96 kHz@24-bit support, so you must have something to "fallback" on. I was thinking about fallback to for example Dolby Digital or something like that, since it's a pretty common audio track on DVD's and HD-DVD's on the market. It would, of course, have to be a track with 48kHz sound, which is more then enough for a movie. Again, let's make this clear - I'm not saying this is a bad thing because it isn't, 48kHz is more then enough). Somewhere in the back of my mind was a thought that maybe, just maybe R(V)6x chips might be doing some internal transcoding/downmixing to stereo or transcoding from TrueHD to LPCM or similar codec to a more "suitable" format. It would also have to be connected to the HDMI standard that's supported in hardware. Is it HDMI 1.1? 1.2? 1.3? If there's HDMI 1.3 support, there are absolutely no bandwdidth constraints for doing 96kHz@24-bit sound TrueHD through HDMI. So, we did the only thing we could - checked with AMD. What we found out is "on par" with our expectations, and it goes like this: HDMI 1.2 is supported, there's no 96kHz sound support. Hardware doesn't do any audio transcoding, this is actually performed by software that you use for HD-DVD playback. Since there are not that many HD-DVD titles out there with Dolby TrueHD support, this shouldn't be a problem, and even those have Dolby Digital support so - no problem. And you know what? We agree. On the other hand, we should note that it would be extremely difficult to even test this at this point because - quite frankly - HD-DVD drives for PC's are very rare and hard to get. Again, we think that the only possible situation where HDMI connector is going to be a factor right now is if someone does a MM PC (barebone or something) for his living room and has a plasma/LCD TV screen with HDMI connector. HDMI connectors are very rare on LCD monitors so no much sense there.