HD Audio analogue output needed - AVS Forum
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post #1 of 13 Old 10-15-2008, 03:02 PM - Thread Starter
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i am realy confused about hd audio and spent hours trying to get my head around what should be something simple
decision i have is either to buy an expensive av amp with hdmi 1.3 or stick with my excellent existing amp and feed it analogue 5.1.
the latter is preferable but i am hitting a brick wall finding what soundcard/software will do a good job of processing the hd source and send it to the amp in analogue
powdvd is my prefered software but whats this all about anydvd needed?
soundcards that look good are the asus xonar dx and Auzetech cinema
will this work??
going insane here
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post #2 of 13 Old 10-15-2008, 03:20 PM
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Quote:
Originally Posted by pacemaker View Post

i am realy confused about hd audio and spent hours trying to get my head around what should be something simple
decision i have is either to buy an expensive av amp with hdmi 1.3 or stick with my excellent existing amp and feed it analogue 5.1.
the latter is preferable but i am hitting a brick wall finding what soundcard/software will do a good job of processing the hd source and send it to the amp in analogue
powdvd is my prefered software but whats this all about anydvd needed?
soundcards that look good are the asus xonar dx and Auzetech cinema
will this work??
going insane here

Does your motherboard have analog out? It could just be as simple as that; Miniplug -> RCA jacks. If you can do that, try it out first and see if you're satisfied before spending more money. PowerDVD will decode HD audio before sending it to your receiver.
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post #3 of 13 Old 10-15-2008, 11:51 PM
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Right now, in HTPC-land, the software is doing all the HD encoding. Within the next 2-3 years, the HDMI thing will get figured out and cheap soundcards/video cards that pass HD audio will be everywhere. I would save your money, use your CURRENT receiver and your sound card's analog outs. When it all gets sorted out, you'll be able to get twice the quality of HDMI receiver that you could now for the price. So for FREE, right now, you'd get to enjoy HD audio, letting everything settle down and figure itself out. Which it will. In a couple years...

In terms of LFE, size does matter!
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post #4 of 13 Old 10-16-2008, 02:33 AM
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The downside of going through analogue afaik right now, is that the software players are still downsampling the signal when they do the decoding so essentially your getting a plain dolby/DTS track that has been decoded by the player sent through analogue to your receiver...

In this case, you might as well keep using SPDIF, at least that way the signal gets transferred digitally to your amp and you can enjoy your receiver's decoding abilities some more ;-)

Unless someone knows whether ther's some playback software available that doesn't downsample? In that case I would jump on that myself and hold out untill HDMI and bitstreaming have become mainstream...
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post #5 of 13 Old 10-16-2008, 02:52 AM - Thread Starter
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let me see if i am getting this at last
the software decoding currently used in say powerdvd downsamples the hd audio then eith oputputs this altered signal either through its spdif OR analogue outputs?
so either way you dont get hd?
the only benefit to use the soundcards audio out would be if its dacs were batter than that in you amp?
however if i have a hdmi output on my video card that outputs 1.3 and a receiver that accepts it that WOULD be the only way to enjoy the hd audio
am i getting there?
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post #6 of 13 Old 10-16-2008, 03:14 AM
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Quote:
Originally Posted by pacemaker View Post

let me see if i am getting this at last
the software decoding currently used in say powerdvd downsamples the hd audio then eith oputputs this altered signal either through its spdif OR analogue outputs?
so either way you dont get hd?
the only benefit to use the soundcards audio out would be if its dacs were batter than that in you amp?
however if i have a hdmi output on my video card that outputs 1.3 and a receiver that accepts it that WOULD be the only way to enjoy the hd audio
am i getting there?

yes that's pretty much what it boils down to. Though I have to admit I didn't follow up on the situation so maybe in the meantime there might have been some changes with the software...
The way I understand it is that when using analogue, the player decodes and downsamples and when using SPDIF the mandatory non-DD+ (so the regular DD or DTS) track gets sent to your receiver for decoding.

Using HDMI from your vid card would at best give you the ability to stream linear PCM to your receiver: the software player decodes, but the uncompressed stream gets set to your receiver via HDMI. No decoding gets done by your receiver because the signal is not PAP-conform.
Using HDMI via Asus Xonar HDAV1.3 would give you the only way at this point to get actual bitstreaming to your receiver which would then be responsible for the decoding of the signal. I do not have an idea however how good the Asus is doing since at first there were some issues....
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post #7 of 13 Old 10-16-2008, 03:42 AM - Thread Starter
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sorry are you saying that even hdmi 1.3 from my vid card wont give hd audio out to my amp and i have to use an asus xonar hdmi card ?
if that was so surely i would then have to have an amp that will accept seperate hdmi inputs one for video and the other for the audio, does that exist?
i really cant understand why the soundcard dosnt just decode the hd audio and then output the full signal through its analogue oututs

so:

Digital
1 those using hdmi1.3 from their video card are NOT getting HD audio
2 the only way to get this is via an Asus card

Analogue
1 the only soundcard i can find that supports 192kb MULTI channel audio again is Asus
2 this requires the sofware player ie power dvd to send the hd audio signal to the asus's dacs which at the moment it will not
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post #8 of 13 Old 10-16-2008, 05:13 AM
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Quote:
Originally Posted by pacemaker View Post

sorry are you saying that even hdmi 1.3 from my vid card wont give hd audio out to my amp and i have to use an asus xonar hdmi card ?
if that was so surely i would then have to have an amp that will accept seperate hdmi inputs one for video and the other for the audio, does that exist?
i really cant understand why the soundcard dosnt just decode the hd audio and then output the full signal through its analogue oututs

so:

Digital
1 those using hdmi1.3 from their video card are NOT getting HD audio
2 the only way to get this is via an Asus card

Analogue
1 the only soundcard i can find that supports 192kb MULTI channel audio again is Asus
2 this requires the sofware player ie power dvd to send the hd audio signal to the asus's dacs which at the moment it will not

sorry, but I can't tell it any plainer than it already is...
those that are using HDMI 1.3 from their video card (ONLY in case this is a video card capable of passing along LPCM audio such as ATI 4850 and 4870) are capable of receiving a decoded (by the player) LPCM signal in their receiver. Whether this signal is still the HD Audio signal is unknown to me as I do not have such a card or resever. In any case, here the possibility also exists that the signal gets downsampled by the player...

The only way AFAIK to get full HD audio right now is if:
- you have the Xonar HDAV
- you have a receiver with the capability of decoding DD+/TrueHD
- you have a software player that can pass the bitstream along (TMT/PowerDVD). Where TMT is concerned, this soft is bundled with the Xonar.

You are right about the analog part. I'm just unsure whether only an Asus card will be able to output multi 192...
Either way, this doesn't look like an issue to me as 24/96 multichannel is what is used....
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post #9 of 13 Old 10-16-2008, 05:30 AM
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another thing worthy of note is the following from the blu-ray faq:

Will Blu-ray down-convert analog outputs?


No, Blu-ray players will not down-convert the analog output signal unless the video contains something called an Image Constraint Token (ICT). This feature is not part of the Blu-ray Disc spec, but of the AACS copy-protection system also adopted by HD-DVD. In the end it will be up to each movie studio to decide if they want to use this "feature" on their releases or not. The good news is that Sony, Disney, Fox, Paramount, MGM and Universal have already stated that they have no intention of using this feature. The other studios, which have yet to announce their plans, will most likely follow suit to avoid getting bad publicity. If any of the studios still decide to use ICT they will have to state this on the cover of their movies, so you should have no problem avoiding these titles.


This to me would mean that if the HTPC Software players downconvert, it is actually a bug rather than anything else
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post #10 of 13 Old 10-16-2008, 06:58 AM
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Quote:
Originally Posted by DisTreSs View Post

another thing worthy of note is the following from the blu-ray faq:
[i]Will Blu-ray down-convert analog outputs?
No, Blu-ray players will not down-convert the analog output signal unless the video contains something called an Image Constraint Token (ICT)....

This has nothing to do with audio. It is referring to video resolution and component output downconversion.


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post #11 of 13 Old 10-16-2008, 08:39 AM
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Originally Posted by hammerdwn View Post

This has nothing to do with audio. It is referring to video resolution and component output downconversion.


Thx 4 the heads-up... scanned right passed that
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post #12 of 13 Old 10-16-2008, 10:16 AM
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The problem with down sampling is NOT that you don't get HD audio ...you do. With regular legecy DD (max 640kbps) and dts (1.5mbps) you get a sample rate of 48kHz and a bitdepth of 16bits, what is occuring now with COMMERCIAL software players is they do not conform to PAP standards and as such any and all HD audio gets bitstripped to 16 bits and resampled to 48kHz (the latter not really a problem since only 4 titles have 96kHz sampling ...music only). This is still HD audio tho and has the data to back it up, giving encoded rates of between about ~2-6Mbps. This information is significantly higher than any legecy source and sounds as such. The real issue is people are p**sed that they have paid for 24bit soundtracks but are unable to access them. It is quite doubtfull you would here a really massive diff (like legecy vs HD sound) but its the principle. With some HD movie soundtrack they are 16/48 anyway but not compressed so these are not effected but due to the extra bandwidth they can very well be called HD. Currently there is only two way to get FULL HD sound: 1. is with the Xonar HDAV and have it bitstream the sound to a compatable receiver for decoding (wouldn't recomend this at the mo ...still got beta drivers and doesn't work at all on vista). 2. do a remux of your HD/blu disc to mkv and convert your sound to FLAC. This can be passed (due to no DRM) at full sampling rate and bitdepth by any analogue sound card or digitally as LPCM via HDMI by multichannel PCM compatable chipset i.e. G45, nvidea 8200/8300 or one of the ATI HD4XXX series graphics cards. If anybody is interested in the cheaper 2nd option, heres a guide to tell you how you can go about it:

http://www.avsforum.com/avs-vb/showthread.php?t=1033822

Hope that has cleared a few things up and has been helpfull.
Cheers,
Jiff.


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post #13 of 13 Old 10-16-2008, 11:37 PM
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Quote:
Originally Posted by DisTreSs View Post

The downside of going through analogue afaik right now, is that the software players are still downsampling the signal when they do the decoding so essentially your getting a plain dolby/DTS track that has been decoded by the player sent through analogue to your receiver...

In this case, you might as well keep using SPDIF, at least that way the signal gets transferred digitally to your amp and you can enjoy your receiver's decoding abilities some more ;-)

Unless someone knows whether ther's some playback software available that doesn't downsample? In that case I would jump on that myself and hold out untill HDMI and bitstreaming have become mainstream...

If you can tell the difference between 16-bit and 24-bit audio tracks at like 3.5mbps, I'll eat my hat. Its a non-issue for like 95% of the people's audio gear here.

In terms of LFE, size does matter!
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