More than alittle confused about audio for a HTPC - AVS Forum
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post #1 of 23 Old 03-19-2012, 01:50 PM - Thread Starter
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Ok folks I am trying to do something alittle different here so finding the information is alittle tricky. I figure since I am building a HTPC why not use software to decode my audio (maybe with some future room correction software) and send out 8ch LPCM to an external DAC. This way I could avoid having to by an expensive pre/pro and instead I can just buy an 8ch pro type DAC with a volume control.

Here is where the confusion starts .... the details. The only way I can see sending out 8ch LPCM is over HDMI, but all the pro audio multichannels DACs only accept firewire or spdif (is that 2ch or 8ch ?) Do filters like ffdshow allow my computer to decode the 5.1 and 7.1 compressed formats and just send out the 8ch LPCM ?

My motivation is I think I can spend money on a quality multichannel pro DAC and use my HTPC to decode the 5.1/7.1 formats and get better performance than spending the same money on a consumer pre/pro and bitstream from my HTPC.

Anyone else tried to do something like this ?
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post #2 of 23 Old 03-19-2012, 02:37 PM
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What kind of files/file types are you playing?
DVD, Audio, CD, Blu-Ray??

What is your definition of expensive?

Usually the best way to get audio from a HTPC is to bitstream it; anytime there is software involved, I wouldn't trust the signal coming out. Maybe someone here has some experience with it and has a solution.

For instance, here's my setup: I have a HD5450 video card to send the original audio signal from the HTPC to my AVR (which has pre-outs). I am using this AVR as a Pre/Pro to feed the analog signals to a 7-channel Emotiva amp.
I am not an audiophile by any means so this is more than sufficient for my needs.

There have been threads where users have used expensive sound cards in their PCs to decode the sound and send out 8-ch analog audio. You might want to look into that too.
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post #3 of 23 Old 03-19-2012, 02:41 PM - Thread Starter
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If you look around the high-end forum alot of the top pre/pro are starting to include the Dirac Live room correction. Dirac is now offering a software version of this

http://www.dirac.se/en/consumer-products.aspx

So unless this software is going to re-encode It will have to output LPCM.
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post #4 of 23 Old 03-20-2012, 12:07 PM - Thread Starter
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In case anyone else was wondering I did get an answer, thanks Carl !

Looks like I will be using something like the Lynx AES16, running an ASIO driver. I will be using FFdshow to decode the multichannel formats, and the Dirac Live and it's driver will appear as a virtual soundcard. The Dirac Live soundcard will output the LPCM over the 16channel AES/BEU Lynx card to an external DAC. Now I might have to rethink the DAC and volume control.
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post #5 of 23 Old 03-20-2012, 12:09 PM
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post #6 of 23 Old 03-20-2012, 12:16 PM - Thread Starter
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No clue what you are talking about The Lynx mentions having drivers for WDM and ASIO.
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post #7 of 23 Old 03-20-2012, 12:18 PM
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Quote:
Originally Posted by HFGuy View Post

No clue what you are talking about The Lynx mentions having drivers for WDM and ASIO.

WASAPI is supported by the new motherboards with no latency. Soundcards are not needed even for audiophiles.

We have tested extensively and worked with a few as consultants.
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post #8 of 23 Old 03-20-2012, 12:32 PM - Thread Starter
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If you use the motherboard what are you outputting the audio over ? HDMI isn't going to be an option for me as I am trying to replace an AVR with a pro multi-ch DAC.
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post #9 of 23 Old 03-20-2012, 12:38 PM
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Quote:
Originally Posted by HFGuy View Post

If you use the motherboard what are you outputting the audio over ? HDMI isn't going to be an option for me as I am trying to replace an AVR with a pro multi-ch DAC.

True. You can add spdif coax to many boards though. And almost all boards also come with toslink out as well.
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post #10 of 23 Old 03-20-2012, 12:56 PM - Thread Starter
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My understanding was that spdif coax and toslink was limited to well under 8channels.
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post #11 of 23 Old 03-20-2012, 01:05 PM
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Quote:
Originally Posted by HFGuy View Post

My understanding was that spdif coax and toslink was limited to well under 8channels.

I see your dilemma now.
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post #12 of 23 Old 03-20-2012, 01:16 PM - Thread Starter
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I always have to be difficult, I get a kick out of this stuff, trying to find a new and better way to do things.
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post #13 of 23 Old 03-20-2012, 05:57 PM
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S/PDIF is limited to stereo PCM.

ffdshow Audio Decoder can't decode DTS-HD. You have to use LAV Audio Decoder + dtsdecoderdll.dll (included in ArcSoft TotalMedia Theatre).
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post #14 of 23 Old 03-20-2012, 06:10 PM
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Quote:
Originally Posted by renethx View Post

S/PDIF is limited to stereo PCM.

Correct. I got caught up in the asio vs wasapi audiophile chatter and forgot he wanted 7.1.
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post #15 of 23 Old 03-20-2012, 06:25 PM - Thread Starter
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Thanks guys, I appreciate your attention. I still have ALOT of details to work out, but I wanted to make sure I am going in the right direction. Carl has also been a big help understanding how my HTPC will be formed. And now because of him I am also looking at some DIY DACs with volume control ... yes I need help
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post #16 of 23 Old 03-20-2012, 09:56 PM
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do they not make hdmi receivers that can function as high end dacs?
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post #17 of 23 Old 03-21-2012, 05:52 AM
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Quote:
Originally Posted by MlNDBOMB View Post

do they not make hdmi receivers that can function as high end dacs?

They do. Just don't use the amplifier.
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post #18 of 23 Old 03-21-2012, 07:14 AM - Thread Starter
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I am starting to look at some DIY DACs ... I am already going off the beaten path, why not go all the overboard
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post #19 of 23 Old 03-21-2012, 08:12 AM
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I also got the similar problem as HFGuy. I built my HTPC recently with ASUS P8H67-M-EVO +i3-2100T, my plan was to use VGA connect to a touchscreen to operator the HTPC, while connect HDMI to my receiver for lossless music,since these lossless files are too big for SPDIF to transfer. But now if I didn't turn on the TV which connect to my receiver, FB2K can't find my receiver in the output device. I guess this is because the motherboard didn't detect video output through HDMI, so HDMI doesn't function in this case, can someone help with this?
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post #20 of 23 Old 03-21-2012, 08:46 AM
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Quote:
Originally Posted by fubird View Post

I also got the similar problem as HFGuy. I built my HTPC recently with ASUS P8H67-M-EVO +i3-2100T, my plan was to use VGA connect to a touchscreen to operator the HTPC, while connect HDMI to my receiver for lossless music,since these lossless files are too big for SPDIF to transfer. But now if I didn't turn on the TV which connect to my receiver, FB2K can't find my receiver in the output device. I guess this is because the motherboard didn't detect video output through HDMI, so HDMI doesn't function in this case, can someone help with this?

The size of the file has nothing to do with if the audio stream can be sent over S/PDIF. Audio is limited to stereo in S/PDIF and the supported frequency is usually 44.1kHz, 48kHz, 96kHz, 192kHz. So if you try to play a 5.1 88.1kHz file, you are out of luck.

AVR is considered as a display device. Make sure to select extended desktop mode. Then video is always sent to AVR, along with audio.
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post #21 of 23 Old 03-21-2012, 09:22 AM
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Quote:
Originally Posted by renethx View Post

The size of the file has nothing to do with if the audio stream can be sent over S/PDIF. Audio is limited to stereo in S/PDIF and the supported frequency is usually 44.1kHz, 48kHz, 96kHz, 192kHz. So if you try to play a 5.1 88.1kHz file, you are out of luck.

AVR is considered as a display device. Make sure to select extended desktop mode. Then video is always sent to AVR, along with audio.

Thank you renethx. I will try this setting. Another question on the setting for FB2K and AVR. I got some FLAC file which are 16bit, and my AVR D/A is 24bit/192KHz, should I set in FB2K the output format to 16bit or 24bit?
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post #22 of 23 Old 03-22-2012, 02:12 PM - Thread Starter
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I think I am going to use 4 of these operating in stereo-mode

http://www.twistedpearaudio.com/digital/buffalo.aspx

Not sure how to do the volume yet. I will need to experiment to see if an analog attenuator is worth the extra cost and time compared to the digital volume on the ESS DAC. I would also like some way to control the volume via the HTPC, so i'll need some interface between the DAC and the HTPC.
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post #23 of 23 Old 03-22-2012, 03:52 PM
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Quote:
Originally Posted by fubird View Post

Thank you renethx. I will try this setting. Another question on the setting for FB2K and AVR. I got some FLAC file which are 16bit, and my AVR D/A is 24bit/192KHz, should I set in FB2K the output format to 16bit or 24bit?

Either one that works. 24 bit is just 16 bit padded to 24 bit in such a case so that you neither get nor lose anything.
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