Auzentech HomeTheater HD Preview: Bitstreaming True HD/DTS-HD MA
by Anand Lal Shimpi on September 2, 2009 12:00 AM EST- Posted in
- GPUs
Last year ASUS released the Xonar HDAV; it’s a sound card. The Xonar HDAV’s claim to fame was its ability to bitstream Dolby TrueHD and DTS-HD MA over HDMI. Don’t have any idea what that means? I wrote a primer here last year, but I’ll give you the quick rundown.
Blu-ray discs are huge, you can store up to 50GB on a dual-layer disc. That’s not enough to store lossless video, but it’s enough to store lossless audio. In other words, you can have a bit-for-bit reproduction of the audio track that was mastered at a movie studio in your own home. For most consumers it’s cool as hell just for bragging rights, but for some super high end home theater enthusiasts it’s a perceived necessity.
These audio tracks are stored using one of two lossless compression algorithms: Dolby TrueHD or DTS-HD Master Audio. The content owners however were very nervous about putting these audio tracks on BDs, specifically allowing PC users access to them. After all, if you had unencrypted access to one of these tracks you could potentially...uh...idunno, turn them into MP3s? Stop going to the movies? I have no idea. Regardless, the studios were nervous and the result was a ridiculous requirement for security.
In order to play one of these tracks you have to properly implement what’s called a Protected Audio Path (PAP). I go into much greater detail about the encryption/decryption requirements for a PAP but you need OS, software, driver and hardware support for it. Windows Vista gave us OS support, ArcSoft and Cyberlink gave us software support and the GPU vendors gave us driver support - all we were lacking was the hardware.
The GPU vendors didn’t include support in their designs for a number of reasons, so no integrated or discrete graphics currently support sending these compressed audio streams over HDMI. Next year that will change, but for now it is what it is.
The only hope was for sound card makers to tackle the problem, but the sound card market isn’t what it was back in the 1990s. ASUS was the first to take it seriously, because, well, ASUS takes everything it does seriously.
The Xonar HDAV launched and as you’ll see, I haven’t reviewed it. When it first hit, driver support wasn’t there. Despite the hardware support, you couldn’t send TrueHD or DTS-HD MA over HDMI because the driver didn’t allow it. This part took months to fix, it took some more months to work out a number of other bugs and in that period I just gave up on it. I went back to it not too long ago and while it worked, I’d lost my interest.
Before I ever heard of the ASUS card I heard that Creative Labs and Auzentech were working on one. I even wrote about it. I actually expected it to be out first, but for whatever reason it got pushed back. The card finally launched this year and today it finally received support from Cyberlink to bitstream these codecs without any loss in quality. The PowerDVD 9 patch notes tell you right here:
You do need PowerDVD 9 for this to work, no it doesn’t come bundled with the card, yes the latest patch is needed for it to work.
Auzentech sent me a card and I went to testing it. Perhaps it would be my one last hurrah with high end HTPCs before I accept fate and build a modest XBMC box for my needs.
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123sex - Wednesday, September 2, 2009 - link
Doesn´t look like a 24 bit dischttp://www.blu-raystats.com/Search/displayTitles.p...">http://www.blu-raystats.com/Search/displayTitles.p...
http://www.blu-raystats.com/Stats/Details.php?u=42...">http://www.blu-raystats.com/Stats/Details.php?u=42...
vs 24 bit
http://www.blu-raystats.com/Stats/Details.php?u=41...">http://www.blu-raystats.com/Stats/Details.php?u=41...
Which makes perfect sense considering the age of the movie
(sorry about the other post)
jay401 - Wednesday, September 2, 2009 - link
Thanks for reviewing this! Auzentech has made some excellent cards and it's rare anymore to see a review of a peripheral soundcard since most folks aren't concerned enough with their sound quality or decoding to go beyond whatever onboard sound their motherboard provides.andy o - Wednesday, September 2, 2009 - link
See anything wrong? While the output frequency is correct, the output resolution is not. If I’m correct, we should be seeing 48kHz/24-bit audio, but instead we’re getting downsampled 48kHz/16-bit audio - the same we get over LPCM. It’s close, but not technically lossless.I hope you realize that you're still getting whatever is in the disc, right? That's the point of bitstreaming. The error is just on PowerDVD's display. Maybe that's what you meant, but the way it's worded seems to say that you're getting something else. And, it clearly says 192 kHz, not 48 kHz.
Anand Lal Shimpi - Wednesday, September 2, 2009 - link
I was under the impression that the discs I used contained 48kHz/24-bit tracks, I'm checking to see if I have anything else here confirmed to be a 24-bit disc.Either way I do not believe the output frequency should be 192kHz, very few BDs are mastered with a 192kHz audio track.
Take care,
anand
andy o - Wednesday, September 2, 2009 - link
Sorry, one more and I'm done.If you notice, your receiver indeed is telling you it's receiving only 5.1 audio both in the THD and DTS MA example pictures. And again, there's no way PowerDVD could downsample the audio without decoding it first. Then it would have to encode again. It's not just very unlikely, but there's also no reason whatsoever that they would do it, and it would take extra effort to re-encode the TrueHD and DTS MA streams on-the-fly so your receiver gets them. I don't know if it's even possible to encode those formats on-the-fly.
Anand Lal Shimpi - Wednesday, September 2, 2009 - link
Wow, you're more than completely right (a night of rest and the whole downsampling without decoding thing hit me right in the face). I've updated the article, it looks like the most that's happening is PowerDVD is just providing screwy output but the card is working as intended.Thanks again :)
Take care,
Anand
andy o - Wednesday, September 2, 2009 - link
BTW, 24.576 Mbps is exactly uncompressed PCM 16-bit 192 kHz 8-channel, which are the numbers that PowerDVD is reporting (which is what shows in your pictures). It is not reporting the bitrate of the TrueHD audio. Somehow it can't read the true specs of the THD and DTS MA streams. No big deal.Also, note that the movies you tested don't have 7.1 (8-channel) audio, so again, PowerDVD is clearly misreporting, and you can easily double check this with your receiver, which will tell you how many channels it's receiving/processing.
andy o - Wednesday, September 2, 2009 - link
Of course, what I'm pointing out is that 192 kHz is ridiculous... the only one I know that does that (movie) is Akira. Also, the 24 Mbps audio should be a tip that PowerDVD is just misreporting.In any case, once your receiver tells you it's getting TrueHD or DTS MA, you're set. There is no way downsampling is being done, no matter what PowerDVD tells you. The only way would be that the card is getting the downsampled PCM output from PowerDVD and re-encoding it to THD or DTS MA, but you see how that's very extremely unlikely.
andy o - Wednesday, September 2, 2009 - link
first paragraph is a quote from the 2nd page of the article, "quote" doesn't work in the comments typing field?123sex - Wednesday, September 2, 2009 - link
Doesn´t look like a 24 bit dischttp://www.blu-raystats.com/Search/displayTitles.p...">http://www.blu-raystats.com/Search/displayTitles.p...
http://www.blu-raystats.com/Stats/Details.php?u=42...">http://www.blu-raystats.com/Stats/Details.php?u=42...
vs 24 bit
http://www.blu-raystats.com/Stats/Details.php?u=41...">http://www.blu-raystats.com/Stats/Details.php?u=41...
Which makes perfect sense considering the age of the movie