(My apologies. I realized there was an HTPC subforum after I posted this. This may fare better there.) Building a new home theater system and had questions on pushing audio with GTX 580 via HDMI. I do not have a dedicated sound card. Will any audio quality or surround sound decoding capabilities be lost by connecting the computer to the AV receiver from the GTX 580 via HDMI? I saw a couple postings saying the GTX 580 can't do "bitstream audio" but I don't know what that means or if it applies to this situation. Will passing the audio through the GTX 580 affect it's graphics performance at all in any way? Thank you for any help you can offer. I really appreciate it. UPDATE- I've done a little bit more reading. Am I correct in saying that the audio passed through the HDMI from the 580 to the receiver will not be touched or modified at all by the card? The GTX 580 will send a purely digital signal to the receiver and the receiver, not the video card, will handle EVERYTHING to do with the audio? The untouched audio simply gets to the receiver via the card. The receiver then does the work. Correct? Or is this incorrect the because the 580 is incapable of sending raw, untouched audio via HDMI to the receiver and that's what bitstreaming is? And if the GTX 580 can't send raw audio does that mean it is incapable of sending DD or DTS surround sound to an audio receiver? If there is no way to properly connect the GTX 580 to the AV receiver for proper surround sound my motherboard is a Asus P8P67 Pro REV 3.0. Is there any way to connect that to the AV receiver for proper DD and DTS audio?
You would need a Toslink optical cable from either an onboard soundcard or an addon soundcard to get surround sound. Your Motherboard has an optical out on it so you would be good to go.
No it's good for any surround sound configuration I have mine on a 7.2 setup. But you need an additional amp for the other side or height speakers.
Wow. I had no idea! For some reason I thought audio over optical was really limited. I was skimming a bunch of stuff early and must've misread. I was under the assumption it could only handle a small amount of channels or something and compromised on quality. That's great. So a toslink cable from my motherboard to the receiver will be able to hand any HD surround sound audio even up to 7.2 without quality loss? And HDMI audio from the card is not an option at all?
HDMI should be able to do 5.1 audio. Nvidia says... HDMI Deep Color, and 7.1 digital surround sound will be added in a Release 260 driver.
The audio chip on your GTX580 does not support any Dolby tech....so, Dolby Digital and DTS are out of the question if you're using HDMI for audio.
For Dolby Digital or DTS, you need a Dolby certified audio chip....which none of the HDMI audio chips used on graphics cards are to my knowledge. The audio chip used on your motherboard (ALC892), is certified for DTS though. You'll also need playback software that supports the Dolby "technology" you want to use. http://www.dolby.com/us/en/consumer/technology/codecs.html Dolby has a list of media playback software that supports their various "technologies"...
I use XBMC which supports DTS and Dolby technologies, I would assume. Will I be able to simply use a toslink cable from the motherboard to the receiver or do I have to get a new audio card in order for this to work?
The GTX580 can send LPCM at up to 192KHz/24bit so there is no problem sending up to 7.1 full bandwidth digital audio to an amp over HDMI. You dont need to send DTS or DD over HDMI, the video player can decode them to PCM and send them to the amp that way. You dont need to use SPDIF (TOSlink, coax), this would limit the maximum quality for surround sound as SPDIF needs to use Lossy compression to fit surround sound down it. I just verified my GTX580 with Totalmedia Theatre playing Iron Man Blu Ray which is a TRUEHD 48KHz/24bit movie. To play the Hi Def tracks, in the "movies" menu, select TRUEHD audio. Thats it, the player will decode the output and play it at 48KHz 24bit PCM if your hifi/card doesnt support the TRUEHD codec. You can also force the "player" to output to PCM, in which case it will play at up to 192KHz (upsampled) 24bit if your amp supports it. There is no need for DD/DTS support, all players can easily send every bit of data as PCM. You were correct, SPDIF is limited when using more than stereo. You cannot send 5.1 or 7.1 High Definition audio down SPDIF, it doesnt have the bandwidth. It can play stereo without loss in quality, not 5.1 or 7.1. 5.1, 7.1 need to use lossy compressed, this is why the DTS and DD lossy compression codecs were created. Its a good solution and will work great. Not as good quality as a decent analogue soundcard, but that can get a bit more difficult depending on the card you have. To match the quality of a good soundcard you need a pretty expensive amp! Dont use TOSlink !!
But if the audio is already encoded in DTS or DD, say in an MKV you ripped from a Blu-ray, it can be sent via S/PDIF, correct?
Does the motherboard, in my case the Asus P8P67 Pro, need any specific requirements in order to pass the surround sound? Like, does it need to specifically be capable of DD or DTS or because it has S/PDIF it can send them no matter what? Another question- if most audio from movies, such as DD and DTS, is already encoded what is an example of unencoded audio? And if I connect my GTX 580 to the AV receiver and the receiver to the TV is this going to register as two displays on the computer? Will this force my GPU to work harder or effect gaming performance?
When using HDMI for audio, the motherboards audio features arent used. You only need DD/DTS encoding if you want to send 5.1 down ""SPDIF"". Thats all it is for, to get 5.1 or higher down SPDIF by compressing it. If you have a full 7.1 uncompressed connection to your amp (ie HDMI or analogue), then DD/DTS isnt needed at all, there is no need to compress anything. If you are playing back material that is already pre-encoded in DD/DTS, then the PC will decode it into PCM and pass PCM to the amp. Alternatively, you can use the "pass through" option if the video player supports it and send the DD/DTS stream directly to the amp (through whatever digital connection you like, it shouldnt work on analogue because you cant pass a digital stream over analogue), where the amp will decode it. Un-encoded audio is PCM or LPCM. But there are hi def encoded formats that are not lossy, these are for lossless compression and copy protection. You have the choice of letting the player decode them into PCM (like I demonstrated with Iron Man earlier) or passing them to the amp to be decoded there if the video card can forward the codec AND the amp can decode the format. The GPU wont work harder unless you are using surround video. If you select one display to game on, then the other will keep what was on it before or go blank. If you select to display the same on both screens, then it is only rendering one screen and passing it to 2 displays, there is no overhead on the GPU.
Sorry, I should have said Does the motherboard, in my case the Asus P8P67 Pro, need any specific requirements in order to pass the surround sound via S/PDIF? Like, does it need to specifically be capable of DD or DTS or because it has S/PDIF it can send them no matter what?
Depends where the surround sound is coming from. If it is pre-encoded surround sound, then you only need the pass through option to send it directly to the amp where it is decoded into PCM. The video player or onboard soundcards features should provide you with this "pass through" option. If you want 5.1/7.1 Windows, gaming or other surround movie sound to go down SPDIF, then you need a lossy compressor like DD, DTS, DDL. I dont know if your motherboard has support for them, check on the box or the manual, it will say DDL/DTS or DD somewhere. Edit: it appears your mobos soundcard doesnt support lossy compression.
