Author Topic: Is it possible to adapt I2S to USB Audio Standard?  (Read 2182 times)

Offline panzeroceania

  • MassiveMember
  • ****
  • Posts: 133
Is it possible to adapt I2S to USB Audio Standard?
« on: July 21, 2015, 10:21:40 am »
Hello guys, there are several video game systems that have digital I2S internally. There are numerous guides here to adapt that to SPDIF or Toslink. This is helpful to connect your video game system to a home theater setup or AV Receiver.

That said there are more and more commercial DACs on the market that accept USB, and bypass some of the limitations of the aforementioned digital formats. I was wondering if there was a way to adapt the I2S signal to a USB Audio Standard interconnect so that I could interface it with something like a Schiit Audio Bifrost DAC

http://schiit.com/products/bifrost

Offline Hojo_Norem

  • MassiveMember
  • ****
  • Posts: 202
    • JCOM Computer Productions
Re: Is it possible to adapt I2S to USB Audio Standard?
« Reply #1 on: July 22, 2015, 05:15:05 am »
AFAIK, of all of the consoles that have usable I2S lines, none come even close to hitting the limitations of optically or electrically transmitted SPDIF.  SPDIF of today is a lot more capable that what was laid out in the original spec.  With the right equipment and cabling, 192Khz@24bps stereo is possible.

I took a quick look at the link.  By the looks of things, that bifrost DAC has both types of SPDIF input.  All you will need is the regular SPDIF mod for whatever console and a suitable cable.

I'd be surprised if a USB solution exists.  Most likely something custom will have to be designed, and when you start throwing terms around like 'USB Host' and 'USB audio codec', the project jumps a few orders in complexity.  Your best bet would be a fast microcontroller with I2S input and built in USB host controller.  All you would need to do is write the software that would join the two together, and write it good enough to keep latencies to a minimum.
Formerly 'butter_pat_head'

Offline panzeroceania

  • MassiveMember
  • ****
  • Posts: 133
Re: Is it possible to adapt I2S to USB Audio Standard?
« Reply #2 on: July 23, 2015, 02:20:28 am »
@Hojo

thanks for the advice, looks like something like this might be a good place to start

http://www.microchip.com/Developmenttools/ProductDetails.aspx?PartNO=DM320003-3

I'll look into it.

EDIT:

Part of me wonders if it would be a lot easier to pipe the I2S directly into the DAC by hacking the DAC
« Last Edit: July 23, 2015, 02:35:30 am by panzeroceania »

Offline Hojo_Norem

  • MassiveMember
  • ****
  • Posts: 202
    • JCOM Computer Productions
Re: Is it possible to adapt I2S to USB Audio Standard?
« Reply #3 on: July 23, 2015, 05:03:37 am »
Part of me wonders if it would be a lot easier to pipe the I2S directly into the DAC by hacking the DAC

It certainly would be easier and it will also provide the 'best' connection, seeing that you're dealing with the raw audio data and clocks.

But again, I would expect a multi-hundred dollar DAC to have a good enough clock recovery circuit that there shouldn't be any difference between SPDIF and raw I2S...

Or at least any difference that doesn't require hundreds or possibly even thousands of dollars worth of measuring equipment to detect.  ;D
Formerly 'butter_pat_head'

Offline panzeroceania

  • MassiveMember
  • ****
  • Posts: 133
Re: Is it possible to adapt I2S to USB Audio Standard?
« Reply #4 on: July 23, 2015, 08:28:59 am »
I suppose I could buy one of their cheaper models and try it both ways to see what I think

Edit: even if I get perfect audio though,  I'd then have to see what kind of lag I'd be introducing
« Last Edit: July 23, 2015, 08:31:59 am by panzeroceania »