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After reading a bunch of conflicting posts on the net I still have no idea if there really is such a thing as a 7.1 digital stream that can be transmitted to an external 7.1 decoder via SPDIF.
Was thinking about getting a "WINTAL AVR-3015 7.1 CHANNEL HOME THEATRE 130WATT AV RECEIVER" off eBay but it's individual RCA analog inputs only support 6.1 LFront/Centre/RFront/LSide/RSide/REAR/SUB. The speaker outputs cater to two separate rear speakers on top of the side speakers making it 7.1 output. If there is such a thing as 7.1 SPDIF I would hope that this amp would be able to decode it.
If there is such a thing, do all sound cards support this? Does the sound card create this data stream itself for each of the channels? Would be nice to know that if I did the Creative Labs speaker test that I would hear a voice on each separate speaker via the external amp.
the thing to remember is that there is basically no 7.1 content out there to enjoy your 7.1 system on anyway. Even 6.1 content is rare (Lord of the Rings Extended Editions being a BIG exception).
I use the Audigy2 ZS 7.1 card with a 7.1 (analogue outs) speaker system, and it's a bit of a waste as the only thing that handles it is setting SPDIF passthrough in the DVD Decoder and getting the Audigy to decode the 6.1 stuff, and it's actually pretty crap at it. Acceptable I suppose, but far from smooth and seamless. But that's with analogue outs, you're talking about digital outs, so I'm off topic...
BTW, the '6th' in 6.1 is a rear signal that is sent to both the rear speakers, so even a 7.1 system will be 6.1 at best, with two rear speakers both doing the '6th' part. It's cool when it works, and great for LOTR at full volume, but they are only DVD's I have with 6.1.. so worth it?? Good to have the option I suppose..
As for Digital, a digital out from a mainboard or sound card will just transmit (passthough) any digital audio signal that it's given, be it 7.1, 6.1 or 5.1 or whatever. But as there is no discrete 7.1 digital signal from any source, at best it will transmit a DD ES Discrete 6.1 signal in the hope that your receiver or decoder can decode it.
Just had a look at that receiver on ebay... actually looks quite good, the smh review liked it, obviously you'll get what you pay for, but for that money, it looks good. Does DD ES 6.1 decoding as well, so you'd be set. Just don't skimp on THE most important part, the speakers.
Yes, that was what I was gathering from other posts on the net. The bit that puzzled me was if the two rear channels were descrete or not. Clearly not.
My biggest concern was with the Audigy 2 ZS Pro card I have as I'm sure I read on the Soundblaster site that the digital out only supplied up to 5.1 and it said that if you played an audio DVD the digital out was turned off during playback.
I've got a 915 type Intel MB with the std blue/green/pink audio connectors on the back and what looks like an internal SPDIF connector on the board but have no idea what it's capabilities are.
One other post I read suggested that there were quite a few DVD's out there using DTS-ES for 6.1 output. Just cannot understand why 2 speakers feeding the same audio channel would sound better in the back than just a single speaker. Suppose if the space behind the listener is limited it would give a better sense of volume behind your ears.
I already have the speakers. Some time ago I picked up a couple of the Wintal in-wall speakers for the front speakers and Wintal wall mount cube speakers for the rear. I then purchased three Pure Acoustic MAC2000 surround speakers for the sides and center speaker last week to get the full 7.1 happening. My gut feeling with the in-wall speakers was that they would sound a bit muffled but after hooking them into a basic amp and feeding them some audio as a test I was really surprised as to how good they actually sound. Hope the MAC2000 speakers sound as good or better when they turn up.
Might re-enable the in-built sound hardware and see what it can do with SPDIF.
the two rear channels are discrete, i.e the speaker test plays tones in each one, but because there is no such thing as Dolby 7.1, no sources will take advantage of it, so having them discrete is a bit pointless. But yes, the two speakers do spread the rear sound field out more.
I haven't got an external digital decoder, so can't say what'll happen with the SB digital outs. I'd say it should be able to transmit an ES 6.1 signal, but the bit about muting the digital out with an DVD-Audio is probably correct (although, like so many things in PC-land, there may well be a fix for that....)
If you're using a digital output, then the on-board one will be 98%-102% as good as the Creative one.
There is no such thing as 7.1 in the Home Theatre Industry although lots of misinformation is populated by people who should know better.
6.1 is it....although Tomlinson Holiman (Mr.THX) is advocating 10.2 systems!!!
The Centre Rear Channels are the one's causing the confusion with the introduction of DD EX and DTS-ES.
In a nutshell.....the rear centre "channels" are in fact encoded in the rear side channels and the EX or ES Decoder simply extracts this information (a la Pro-Logic) usually with an embedded flag in the DVD program stream to switch your AV Reciever automatically to EX or ES decoding.
The Rear Centre Channel is mono so in the simplest systems you could use one speaker but Dolby recommends two speakers primarily to combat psycho acoustic anomilies in the sweet spot but it does have the side benefit of enlarging the rear soundfield.
When combined with THX processing and discrete amplifier stages the sound from the two rear centre speaker will not be exactly the same so don't mix 'em up.
One exception is "DTS-ES discrete" which has an additional discrete sound track added to the Movie soundtrack that replays without any matrix style post processing.
My 7.1 amp should be turning up today so I'll find out soon how it will all go with just using the SPDIF out for all audio. At the moment I'm a bit unsure if the PureVideo decoder or AC3Filter is handling the audio but I will set both to SPDIF output to be on the safe side.
Curious to see how the amp will direct the rear audio channels on 5.1 DTS with all 7 surround speakers hooked up. Hoping the rear channel audio will be heard mostly in the rear channels. Would be a shame if the rear audio on 5.1 tracks only came out the side channels.
Ended up using a Live! 5.1 card for SPDIF out as the Extigy external SB box I have downmixes all optical out to 2 channel PCM. I use the light orange connector that's at the top of the card with a stereo 3.5 jack to RCA connector into the SPDIF input into the external amp. Red RCA connector I think. Set the creative mixer to digital out, 2channel speaker mode and under settings turn off AC3 decode. In the audio wizard in MCE I selected 7.1 speakers and spdif RCA connector (not sure if these settings have anything to do with the Creative mixer settings).
Uninstalled AC3Filter and set Purevideo decoder to SPDIF out.
I'm assuming the DTS-EX DVD's get decoded as 6.1 on my 7.1 amp and the amp feeds the rear channel to both rear speakers.
There were reports of SPDIF signal volume not being altered by the OS but under rollup 2 it's all seems to be working fine.
Ok, now it seems the PureVideo audio out to SPDIF option has introduced audio sync issues whenever there is a glitch in the DVB transmisison (big time with ABC last night). Had a good muck around with the setting but couldn't fix the sync issue without hitting stop then play every time there was a glitch.
In the end I re-installed the rc1 version (rc2 wouldn't work at all) of AC3Filter and set that up to SPDIF out. For some reason that doesn't have the sync issue after a glitch AND it now seems to output DD AC3 out to the amp on all TV channels, not just all the HD channels (and ABC). So instead of seeing PCM 2 channel come up on the amp I see the DD logo and 2 channel + LFE for all the SD channels. DTS and DTS-EX DVD's get detected by the amp correctly as well when using AC3Filter. Nice, but when it goes out this way it bypasses the volume control so I need to rely on the amp for volume. PCM out seemed to use the Windows volume control. At least it's consistent now. And I can also set the default volume level in AC3Filter for the SPDIF out.
So it looks like the SPDIF option on the PureVideo decoder is poop (sorry to be blunt).
Another unfortunate side effect of upgrading to the latest PureVideo decoder is that the playback now looks like I have that odd frame flash issue but this time it looks like the odd and even fields are getting swapped every now and then. Might see if I can get the previous version working again. I might even load up WinDVD 7 and see how that compares as a decoder on the 1280x720 projector.
Ok, after bit more tv viewing last night and it looks like even the AC3Filter will lose audio sync as well.
Take three - Installed WinDVD7 and used that for mpg2 decoding and audio. This seemed to be ok. I get PCM 2CH to the amp for most of the SD channels (although ABC SD and 9 SD seems to use AC3 audio now) and the AC3 channels feed DD to the amp. The only channel I saw a sync issue on was ABC HD but this only seemed to happen once.
The Intervideo decoder doesn't seem to de-interlace to 50p. Just seems to merge the fields and output 25p. Image looked more blurred as on HD.
Still, 7 HD was working for a change without having to play with settings, most likely because of the basic de-interlacing it uses.
BTW - has ABC and Nine SD always used AC3 rather than an mpeg audio stream?
