Understanding 8-channel LPCM over HDMI: Why it Matters and Who Supports it
by Anand Lal Shimpi on September 17, 2008 2:00 PM EST- Posted in
- GPUs
The Bandaid: The HDMI Sound Card
Ha! I lied; there's more.
No GPUs released in 2008 will support this protected audio path and thus we won't be able to get TrueHD/DTS-HD MA support from a GPU anytime soon. There is another option however: HDMI sound cards.
A couple of companies are working on sound cards with a built-in HDMI repeater, meaning there's an HDMI input, some logic to add data to the HDCP encrypted signal, and an HDMI output.
Your GPU would handle all video decoding and it would send its decoded but HDCP encrypted signal over HDMI, but instead of going to your display (or receiver or pre-processor) it would go next door to your sound card over HDMI (3dfx dongles anyone? At least these are lossless since they are digital signals... oh, hush, Monster).
The sound card would have an audio codec capable of ensuring a protected audio path and would handle all of the audio decoding/bitstreaming in the system. The audio from the sound card and the video from the HDMI input on the sound card would be combined, the HDCP repeated, and the new combined signal sent over HDMI to your receiver/display.
The HDMI spec allows for repeater support (as in devices that add something to an HDCP encrypted HDMI signal and pass along the new combined signal), so the HDMI sound card is really no different than sending HDMI to a receiver and then to your display. There should be no loss in quality or any other negative side effects if implemented properly.
ASUS and Auzentech are both working on these HDMI sound cards that should solve all of our HTPC problems. While both were supposed to be available over the summer, driver and software delays have pushed back both release dates to the last few months of 2008.
The Auzentech card
We have proof that the ASUS card was fully functional at Computex 2008; below are shots of the Xonar HDAV bitstreaming DTS-HD MA to an Onkyo receiver:
The test system
The Card
DVI to HDMI input, then HDMI output
It works!
We’ve got the ASUS card in house and are simply waiting for final drivers before testing it, so expect a review in the not too distant future.
I mainly wrote this quick guide to have something to link back to whenever I list 8-channel LPCM audio over HDMI as a feature. It’s not a typical PC feature like DirectX 10.1 or supporting SSE4, so it needed a little more of an explanation. And there you have it.
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gramboh - Thursday, September 18, 2008 - link
Copy protection on Blu-ray and HD-DVD has been cracked for a while. As predicted by many, it was a big waste of time. You can download full disc images (25-35GB on average) or x264 based encodes with DD5.1/DTS 5.1 sound tracks (4-6GB for 720p and 8-12gb for 1080p) from torrent sites already. It did take a while to fully break (I think AACS on Blu-ray was the challenge) but it has been done, so people are playing these disc images and encodes on HTPC type setups already.Basically the industry is just punishing early adopters. The copy protection is irrelevant (especially HDCP) to people who are going to pirate the material anyway.
The only possible protection they can ever hope for is some online database of keys that players authenticate against before playing a title, but I doubt that level of connectivity (people having their players hooked up to internet 24/7) is closer than 5 years away, at which point uncompressed HDstreaming may be here (current HD streaming is useless and heavily compressed).
So dumb.
jmurbank - Wednesday, September 17, 2008 - link
I agree. Studios still in the brick and mortar business. Today's world is about buying media from the internet and downloading the bought media like from itunes or zml.com. Then be able to freely be viewed or heard with out any annoying problems in between. People think downloading movies and tv shows for free right thing to do, so studios are forced to hire encryption specialists to help them find a a way to protect their investment from torrent servers at a cost of stating customers guilty for every action they take. There are rumors going around in the open source community that HDCP and other encryption methods that studios have placed in will soon be reversed engineer, so I or others do not have spend an arm and a leg to upgrade all equipment that support HDCP or other encryption tactic. Studios have to spend more time inventing new protection schemes, but when will people stop downloading illegally.7.1 surround sound is for bragging rights and even 5.1 is for bragging rights too. Majority of movies rarely uses the rear speakers in each scene. Also people incorrectly setup surround sound, so they do not get the full effects. Two channels is just enough for movies but people are too brain wash to think that surround sound will be better. In order for surround sound to be better, the listener have to setup it up correctly.
Dolby Laboratories shows diagrams what 5.1 and 7.1 looks like on paper. Again on paper. In the real world paper does not stand ground for setting up surround sound. A good surround sound takes a lot of time to setup. It can take a day or a whole weekend to setup surround sound correctly. Rear channels for example should always create a null area at the listening area, but the sounds should be reflected to provide ambient sound. Using regular speakers as rears can be done but they have to be directed away from the listening area and point they directly at a material to diffuse the sound that will scatter the sound. Fancy rear speakers can be used such as bipole and dipole to ease awkward setups. Rear speakers should be at a height higher than head level while standing, but not at the height while sitting. The front speakers can be directed at the listening area. These are just small tips, but can fill a whole entire book.
Buying the best amps and sound cards should not be stopped there. Buying the best speakers also have to be looked at although do not have to buy the best amplifier and sound cards to get good sound. IMHO, BOSE cube/satellite speakers are not the best. Sound is very psychological. This means your sound system might sound very good one day and the next day sound horrible. It can take a month to setup a good sound system, so do homework or research which store provides a good return policy when you do not like the speakers.
The quality of cable depends on the person. I use OEM oxygen free copper audio cable because it has the less resistance which means more power can pass with out the chances of it overheating. I also build speakers and soon build amplifiers, so I just need to spend the money on surround sound processors. I am thinking of creating a project to provide the open source community to use the GPGPU to decode multimedia content because Linux does not have that support. nVidia removed XVmc support from GeForce8 cards and probably up, so I and many others are left to use high speed multi-processor setups running at 3 GHz or faster to watch HD movies in Linux.
pattycake0147 - Wednesday, September 17, 2008 - link
You mentioned that your home theater is what really got you to take a closer look at this. Are there updates coming soon on the progress? I'm particularly interested on the software side of the project.Anand Lal Shimpi - Thursday, September 18, 2008 - link
I've definitely got a lot of updates that are in the pipeline. The projector actually *just* died so that put a hold on things, not to mention that Omaura getting out of the market threw a wrench in my plans for the HDD/main chassis split.I'll get cracking on some updates in the next week though :)
-A
Guuts - Thursday, September 18, 2008 - link
Click the "Blogs" link, upper left, then on "Anand's Theater Construction" link on the right... I think there's a section or two on his HTPC setup.darckhart - Wednesday, September 17, 2008 - link
The big issue here is working as advertised. If the bluray disc comes with all the super-bloated lossless junk, then by golly I want all that super-bloated lossless junk played back perfectly. I don't want "Oh well see your HDMI version doesn't quite support that so we downsample...etc,etc," or "Oh sorry that part isn't in the 'protected path' so it won't work...etc,etc," or "See all your hardware components didn't support hdcp using hdmi-this or new-fangled-acronym-cable-that." Get your crap together Hollywood and hardware manufacturers before selling me some half-baked product. Oh, and get rid of that DRM junk and FBI warning junk and unskippable trailers junk and any other crap that hinders my viewing experience. I bought the movie to see the movie, not solve 10 jumping puzzles before seeing my movie.fuzz - Thursday, September 18, 2008 - link
couldnt agree with you more.. HDCP, AACS, CSS.. it's all just a big waste of time that hurts the industry a lot more than it helps.but if you are a HTPC user with these same concerns, you really should send a couple bucks to the boys who make AnyDVD.. not only does it remove any need for HDCP compliant BS and allow you to rip any movie (DVD/HDDVD/BD), it has options for stripping all PUOPs from a disc dynamically as well as jumping straight to the movie upon insertion :D
Fant - Wednesday, September 17, 2008 - link
As far as I know even the PS3 doesnt support outputting DTS-HD 7.1 via HDMI. I believe they downsample it to 5.1 in order to output it over HDMI.jnmfox - Wednesday, September 17, 2008 - link
It does support DTS-HD 7.1 but there are reported problems with some blu-ray disks from New Line, Lionsgate and some others, that the PS3 downsamples to 5.1.Follow the link for a list:
http://www.avsforum.com/avs-vb/showthread.php?t=10...">http://www.avsforum.com/avs-vb/showthread.php?t=10...
PatMeenan - Wednesday, September 17, 2008 - link
The biggest problem with a repeater solution is keeping the video and audio signals in sync (a lot easier when they're going through the same device). I hope all of the repeater "HDMI audio" cards support adjusting the timing to compensate.