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AAC passthrough (S/PDIF) solution? (PC to Home Audio)
DOHCtah
post Jun 3 2009, 10:28
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Hi guys,

I've been looking for a solution to output AAC on my PC through S/PDIF to my home audio system. My home audio receiver is capable of independently decoding AAC.

On my computer, I'm using ffdshow. It has options to passthrough AC3 and DTS, but not AAC. If I chose to disable AAC on ffdshow codecs, it still won't work.

I also know of the "convert AAC-to-AC3 on the fly" method, but I really would like to figure out a direct native passthrough to preserve quality.
I've also given thought to switching over to AC3Filter and others, but it doesn't seem like they support it either. If anyone could recommend one that works, it would be helpful

Its possible that I'm missing something very simple here. rolleyes.gif Any help would be appreciated. Thanks!
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cowunder
post Jun 10 2010, 15:57
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QUOTE (DOHCtah @ Jun 3 2009, 10:28) *
Hi guys,

I've been looking for a solution to output AAC on my PC through S/PDIF to my home audio system. My home audio receiver is capable of independently decoding AAC.

On my computer, I'm using ffdshow. It has options to passthrough AC3 and DTS, but not AAC. If I chose to disable AAC on ffdshow codecs, it still won't work.

I also know of the "convert AAC-to-AC3 on the fly" method, but I really would like to figure out a direct native passthrough to preserve quality.
I've also given thought to switching over to AC3Filter and others, but it doesn't seem like they support it either. If anyone could recommend one that works, it would be helpful

Its possible that I'm missing something very simple here. rolleyes.gif Any help would be appreciated. Thanks!


i have the same problem. any ideas?
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slks
post Jul 3 2010, 05:47
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I don't know the technical details of S/PDIF, so I can't say whether or not it's possible to send an AAC stream through it. But even if it is technically possible, I doubt that your equipment would be able to decode it, even if it's configured to decode AAC from discs, flash drives, or however you'd otherwise get it to your receiver. Nobody sends AAC through S/PDIF, so there's little reason for a manufacturer to implement that on their device. Why not just decode the AACs on your PC before sending them down the wire? S/PDIF is perfectly capable of handling 44 or 48 kHz decompressed audio.


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andy o
post Jul 3 2010, 06:29
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The Dolby Headphone device SU-DH1 can decode AAC through its SPDIF input, so I'm pretty sure it's possible. I think my receiver too can do it but I have no way to test it. I have never had the need though but I use HDMI. I understand that with SPDIF it is the only way to get multichannel to the receiver same as with DTS and DD. I suppose there should be a way same as with WMA pro which should also be bitstreamable but no one has implemented it yet.
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Centauri
post Jul 27 2010, 11:42
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QUOTE (slks @ Jul 2 2010, 23:47) *
I don't know the technical details of S/PDIF, so I can't say whether or not it's possible to send an AAC stream through it. But even if it is technically possible, I doubt that your equipment would be able to decode it, even if it's configured to decode AAC from discs, flash drives, or however you'd otherwise get it to your receiver. Nobody sends AAC through S/PDIF, so there's little reason for a manufacturer to implement that on their device. Why not just decode the AACs on your PC before sending them down the wire? S/PDIF is perfectly capable of handling 44 or 48 kHz decompressed audio.


I've been sending AAC and ALAC files to my receiver via optical for ages now. And the on-unit receiver display identifies them as PCM.


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andy o
post Jul 27 2010, 12:14
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You're sending the decoded AAC and ALAC streams to your receiver, you're not sending the AAC stream itself.

This post has been edited by andy o: Jul 27 2010, 12:14
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Centauri
post Jul 27 2010, 12:30
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Ah.

Well, so long as the receiver's DAC is getting to do the conversion. cool.gif

This post has been edited by Centauri: Jul 27 2010, 12:33


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cowunder
post Nov 24 2010, 14:50
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i have the same problem. i've searced many sites, but couldn't find a solution. aac->ac3 loses some quality.
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ramicio
post Nov 24 2010, 17:11
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FFDShow is open source, get to programming. I'd contact the manufacturer to see if there is even a data pipe path possible for this inside of the receiver. It sounds to me like a receiver like this decodes that kind of stuff from a stream over ethernet or from a plugged-in storage. I had an older receiver that had an icon on the VFD display for "MPEG" audio. I never did find out much about it or never did I test it. The receiver was second-hand and Pioneer wanted money for the manual, instead of a free download. This was before receivers had and kind of serial port, USB, firewire, or ethernet connection.
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KFal
post Nov 24 2010, 19:08
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QUOTE (cowunder @ Nov 24 2010, 15:50) *
i have the same problem. i've searced many sites, but couldn't find a solution. aac->ac3 loses some quality.


Are we talking about dual-channel or multi-channel AAC?


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cowunder
post Nov 25 2010, 12:05
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QUOTE (KFal @ Nov 24 2010, 19:08) *
QUOTE (cowunder @ Nov 24 2010, 15:50) *
i have the same problem. i've searced many sites, but couldn't find a solution. aac->ac3 loses some quality.


Are we talking about dual-channel or multi-channel AAC?


both of them. amplifier never said the file is aac.
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citylimits
post Jan 5 2011, 20:33
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Good timing! I got this working last night, so I registered an account on this site to post my hopefully HELPFUL reply!

I had a 720p Blu-ray movie with an AAC encoded multi-chanell audio stream

In XBMC ver. 10 the movie would decode from AAC to Dolby digital surround on my receiver without issue, however I wanted to try playback on Media center classic - Home theater edition just for kicks.

I played around with the settings for about 30 minutes and finally got it to work, i'll post pix later!

I used the latest versions of FFDShow and MCC - Home theater edition, both version are x64 (My HTPC runs Win 7 x64) I also have the latest version of the Haali media splitter.

Because FFDShow is software based and I wanted to have take advantage of hardware based acceleration for H264/VC-1 content, so I don't use FFDshow for video - JUST AUDIO.

As such, the internal filters for DTS/AAC/AC3 are all turned off within MCC HT (media center classic home theater)

Within FFDShow - audio config, I enabled the codecs for AC3/DTS/AAC.

I then went to the MIXER section and set it to 5.1.
Under output I enabled some additional settings which I can't recall @ the moment. I believe I checked EVERY BOX with regards to AC3/AAC/DTS and S/PDIF output though.

Once this was all done, I closed and re-opened MCC - HT and voila ! A Dolby digital icon appeared on my onkyo receiver and I had surround sound. This is the best I can get it working AFAIK, because my Onkyo receiver doesn't support AAC.

The above was mostly an exercise is tinkering as I mostly use XBMC 10 for movie playback now, it doesn't require much of any tinkering for A/V playback to work successfully biggrin.gif
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savantique
post Apr 7 2012, 07:33
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What is MCC - Home Theater Edition? I've never heard of it, unless you mean Media Player Classic - Home Cinema.
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andy o
post Apr 7 2012, 08:31
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I thought he meant that too, but it doesn't matter. What he's doing is not what the OP wanted (almost 3 years ago). He's transcoding to AC3, which is lossy->lossy. The OP wanted to bitstream AAC to avoid this.
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savantique
post Apr 7 2012, 09:37
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From what I understand, only specific hardware can bitstream AAC. I also understand that an HDMI cable running to the TV, that has an optical cable running from the back of the TV to the receiver, cannot stream AAC either?
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andy o
post Apr 7 2012, 15:36
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I don't think so, but nobody is transmitting AAC content, so what your TV can decode/transmit is not important. And even if they were, they would be stupid not to provide some decoder box, cause probably no TVs out there can decode AAC the way they can Dolby Digital, for broadcasts.

I have never seen AAC being bitstreamed, but as I said above I have a decoder. There is not a lot of multichannel AAC content out there though, and if you have HDMI audio, which is possible with even the cheapest modern equipment now, it's moot cause you can just decode it and send multichannel uncompressed LPCM.

This post has been edited by andy o: Apr 7 2012, 15:42
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savantique
post Apr 7 2012, 15:51
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How would I go about doing that, though? I definitely have a multi-channel AAC video, it just downmixes it to stereo on my receiver, though. The AC3/DTS stuff gets properly represented as multi-channel modes on my receiver, on the other hand.

Edit: typo.

This post has been edited by savantique: Apr 7 2012, 15:51
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andy o
post Apr 7 2012, 16:28
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Well 3 years later I still don't know if it's possible with any software, but I have never had the need to. I think the easiest way to do it is by doing the on-the-fly conversion to DD. ffdshow can do it (you can even use another decoder if you wish, then use ffdshow's audio processor AFAIK), or ReClock can also do it. If your PC has a Dolby Digital Live or a DTS Connect card, it can also be done at the driver level. These schemes were created specifically for this purpose, to get any multichannel stream through SPDIF, but in the case of lossy multichannel you'll be doing a lossy->lossy conversion.
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Pusherman
post Apr 7 2012, 17:34
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Have you tried new XBMC? I might remember wrong, but think there was AAC Passthrough checkbox in settings.
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LOCKDOC
post Dec 27 2012, 03:26
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QUOTE (savantique @ Apr 7 2012, 16:51) *
How would I go about doing that, though? I definitely have a multi-channel AAC video, it just downmixes it to stereo on my receiver, though. The AC3/DTS stuff gets properly represented as multi-channel modes on my receiver, on the other hand.

Edit: typo.

Hey fellaz! I have the same prob. Using MPC-HC 64bit + ffdshow 64bit + coaxial cable + yamaha rx-v659
Well, the are no problems with DTS and AC3 bitstreaming to my AV receiver.
But AAC doesn't want. I'm not really good in all this $hi%. I just tried everithing I read here in this topic and still getting PCM signal ((
OK, I dont need to bitstream AAC. Just to encode it to any multichannel format at least.

Can anyone explain me step by step where to go and what to push\tick ?
There are only very few movies with AAC but I want to finish it))

P.S> Sorry so my war from perfect English.
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