Raspberry Pi Forums

Hello,
I was wondering if it would be possible to construct a multi channel ADC that would accept at least 5.1 analogue audio inputs and output a true 5.1 digital audio signal via an optical cable using a Raspberry Pi as a starting point? So far I have been unable to find a PC audio card that outputs true 5.1/7.1 audio via its optical output, all of them only output 2 channel audio and passes DTS and Doloby Digital from DVD's and Bluerays that must be processed by the DTS and Doloby converters in an AVR to produce the 5.1 or 7.1. audio that is then sent to the speakers. I simply do not understand why Sony is able to output 7.1 digital audio via HDMI or optical outputs from the 8 year old design of the PS3 and none of the audio card manufactures that design and build PC audio cards still only output true 5.1 and 7.1 audio via their analogue outputs. This 2 channel solution is ok if all you do is listen to music and watch commercial DVD's and Blueray movies but not for gaming. If you are a PC gamer the only way to get true 5.1 output from the games that support this is to use the analogue outputs from your sound card. After investing in a really good home theater sound system and wanting to utilize it for my PC audio as well I started wondering if constructing a relatively inexpensive ADC using the Raspberry Pi as a starting point were possible. Do any of you have any thoughts on this subject?

Firstly if you want to move 8 channels of audio from your computer to your amp, your not looking for an Analog-to-digital converter because your computer is not Analog. Likely your Amp has a nice DAC so you are looking for a digital-to-digital.

The Raspberry Pi would not be a good starting point for an audio card.
are you sure a mid range audio cards like this:
http://us.creative.com/p/sound-blaster/ ... -audigy-rx
or this:
http://www.asus.com/Sound_Cards_and_Dig ... AV13_Slim/
won't do 7.1 over optical/hdmi?
if not check the high end options from creative and asus.

Options with extra zeros:
http://music.tutsplus.com/articles/buye ... audio-2293
(36 channel craziness, etc)

Hi,
For some reason all of the PC audio cards only output a true 2 channels when using the optical connections. They will all pass through either Dolby digital or DTS digital signals through the 2 channels and then the Dolby and DTS encoders in an AVR will then convert it to a 5.1 or 7.1 stream to the speakers. This is fine as long as you only listen to music and play commercial DVD or Blue Ray movies on your PC. The vast majority of games however support 5.1 audio but do not use DTS or Dolby so the only way to get multi channel audio is via the analogue outputs on the sound card. There is only one or two newer games that are encoded with DTS that will work because this will be sent through the optical connection just like movies. I have tried both the top of the line audio cards from both Creative as well as Asus and they both cost around $250 which is a lot for an audio card. Both companies lied to me with respect to this issue when I specifically asked if they output a true 5.1 audio or if they were in fact only 2 channel digital. And both assured me that they did output true 5.1. When connecting the cards to my $1000 Yamaha AVR and looked at the info about the audio it was receiving from the PC no matter what I as playing on the PC, it was still only a 2 channel signal so the vast majority of games will only be played as stereo. As result of both of these companies lying to me I have returned both cards for refunds because the audio card they would have replaced operated the same way in only having 2 channels for the digital output. On the other hand my 8 year old PS3 is sending a true 5.1 and 7.1 signal to my AVR. Thanks for taking the time in replying to my post.

Can you set your PC up to stream the games sound output to your PS3 over the network? I know that the PS3 can receive streamed media from a PC.

Just to add , the Raspberry Pi has NO analog inputs ,
a peripherial which solves that satisfactorily for your
use-case will be expensive.

ghans

Is it not so much an engineering problem as a patents / IP / DRM / cost problem ? You can pass on an already-encoded stream, but if you encode or decode, you'll have to pay real money.

There was once some custom firmware for creative cards...can't seem. To find it now...but even without that, one should be able to make a loop audio out, use ffmpeg to encode the non-free format and push it out the optical... might be less simple on windows vs linux but it should be doable in just software.