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Show Me The Dolby TrueHD And DTS-HD MA

The HTPC / Windows 7 Chronicles: You Asked, We Answer!

At this point, we’ve veered fairly far from the original purpose of the Windows 7/HTPC piece, but so be it. We’re on a mission now—a mission for the Holy Grail of audiophile/movie enthusiast playback.

As we’ve just established, there are a number of different chipset/discrete graphics solutions able to output multi-channel LPCM audio (several Intel chipsets, a number of Nvidia chipsets, and ATI’s Radeon HD 4000-series cards), but none of them include the Protected Audio Path discussed on the preceding page. As a result, there’s no way to get Dolby TrueHD or DTS-HD Master Audio playback without those lossless codecs being down-sampled to 16-bit, 48 kHz.

Passing HDMI through the Xonar HDAV 1.3 and on to the receiverPassing HDMI through the Xonar HDAV 1.3 and on to the receiver

Ah, but reader bad_code asked about Asus’ Xonar HDAV 1.3—a card that has been in development and “under construction” for quite a while. Just when Asus got its Vista drivers squared away (after much frustration from the community, it’s worth noting), Windows 7 RC1 hits and I move to test it out. Fortunately, I was able to get the Xonar up and running under Windows 7—though not without a bit of tweaking around.

First, bear in mind that all of Asus’ software is currently written for Vista. In order to bitstream DTS-HD MA or Dolby TrueHD, you’ll want to install the most current drivers in Windows Vista Service Pack 1 compatibility mode. This will make it possible to go into the Xonar Control Center and set up the HDMI output settings, and then go into ArcSoft’s TotalMedia Theatre (this is the only software decoder that’ll work with the Asus card to do this) to choose HDMI pass-through.

You’re not out of the woods yet. I ran into two more challenges in the quest to get this working.

The first was TMT3 telling me that my system was not HDCP-compliant the first time I loaded up a Blu-ray disc. This issue only cropped up once the Xonar was added to the system, so there’s a good chance that it can be traced back to a problem with the HDMI path. Think about it. The output is going from the software decoder to the Xonar HDAV to the Onkyo receiver (and to the Samsung TV for video).

Repeaters need to pass information downstream. If any component in this chain doesn't, you run into HDCP compatibility issues.Repeaters need to pass information downstream. If any component in this chain doesn't, you run into HDCP compatibility issues.

If, at any point, a link in that chain doesn’t re-encrypt HDCP content, sets its repeater bit to false, or doesn’t pass downstream info (BKSVs & Bcaps) to upstream devices, the HDCP system may fail. Somewhere in my setup this turned out to be the case. Getting around this failure required a step that the MPAA/AACS would probably prefer enthusiasts would not take. However, had DRM not failed at a very fundamental level it wouldn’t have been necessary. So, I installed Slysoft’s AnyDVD HD and circumvented the problem entirely by bypassing AACS. Shame on such a poorly-implemented rights management system for imposing itself on consumers and then having the gall to fail outright.

The second problem was an incompatibility with certain discs. Despite sporting a TrueHD soundtrack, for instance The Dark Knight would only play back in Dolby Digital. The same went for Body of Lies. Resident Evil: Extinction (also in TrueHD) stuttered all the way through. Meanwhile, Transformers (TrueHD) and Live Free or Die Hard (DTS-HD MA) passed their respective encoded audio streams beautifully, lighting up the Onkyo receiver's corresponding indicators.

Passing DTS-HD through HDMI via Xonar/TMT3...Passing DTS-HD through HDMI via Xonar/TMT3...

...and the Onkyo receiver lights up...and the Onkyo receiver lights up

Update: Asus says that it is not only on the verge of releasing Windows 7 drivers for the Xonar HDAV 1.3, but also about to release an update from ArcSoft’s TMT 2 to TMT 3 for existing customers. TMT 3 didn’t fix our media incompatibility issues, but that’s a major upgrade for the folks who’ve already purchased this card. Also, representatives at ArcSoft claim to have no trouble bitstreaming The Dark Knight or Resident Evil, so we're still trying to figure out why these titles aren't playing back their high-resolution formats.

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