Willakan
Posts: 9
Joined: Mon Oct 31, 2011 3:49 pm

Re: 24 bit/96 khz S/PDIF output using board attached to I2S bus?

Mon Oct 31, 2011 4:02 pm

Hello,

I am amazed, in an ignorant how-did-they-do-that sort of way, at the Raspberry Pi. Obviously, there are quite a lot of things you could potentially do with it; a generic media server has already been bought up as a possibility. I, however, am interested in a more specialised server: a high-definition music streamer, providing bit-perfect outputs at better-than-CD sampling rates.

This would be accomplished through the exposed I2S bus mentioned on the wiki, which would be connected to a board such as this (http://www.twistedpearaudio.co.....m8804.aspx), which would convert the I2S input to a S/PDIF output. Ideally, I would hope this to be capable of 16 and 24-bit audio at 44.1,48,88.2 and 96khz sample rates.

Is this possible with an appropriate linux distribution?

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Gert van Loo
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Re: 24 bit/96 khz S/PDIF output using board attached to I2S bus?

Mon Oct 31, 2011 5:56 pm

I have to be careful not promising what I can't keep: As things stand now, If nothing changes in the next few weeks and the PCB goes ahead as planned, we will have I2S coming out, maybe, hopefully, probably. As for SW driver: sorry I just do the hardware..

Willakan
Posts: 9
Joined: Mon Oct 31, 2011 3:49 pm

Re: 24 bit/96 khz S/PDIF output using board attached to I2S bus?

Fri Nov 04, 2011 5:15 pm

Looking at the distributions being used, they all use the Advanced Linux Sound Architecture as standard, which seems to support all manner of sample rates. I can't see that it would require anything particularly extravagant from a software perspective - whilst I hardly expect it to be plug-and-play assuming the I2S bus is present on the final PCB it all looks quite feasible.

If resampling turns out to be required for high-resolution audio files, will the CPU hold up. Obviously, the Pi can manage HD video, which is quite impressive, but then that's GPU accelerated unless I'm much mistaken.

carlosfm
Posts: 132
Joined: Fri Oct 21, 2011 3:23 pm
Location: Lisbon, Portugal

Re: 24 bit/96 khz S/PDIF output using board attached to I2S bus?

Sat Nov 05, 2011 12:09 am

There seems to be some confusion between I2S and I2C, which are completely different things.
Could you please clarify it there is really I2S signals that we could use for connecting an audio dac or I2S to S/PDIF converter?

This is my thread, where I asked several related questions:

http://www.raspberrypi.org/for.....#038;t=946

Thanks in advance.
Do you Pi?

jasonpatrick
Posts: 2
Joined: Fri Nov 04, 2011 10:29 pm

Re: 24 bit/96 khz S/PDIF output using board attached to I2S bus?

Sat Nov 05, 2011 12:59 am

Re the question on the other thread, suspect you found the details on the Wiki for the alpha board: http://elinux.org/RaspberryPiB.....I2S.2C_SPI

carlosfm
Posts: 132
Joined: Fri Oct 21, 2011 3:23 pm
Location: Lisbon, Portugal

Re: 24 bit/96 khz S/PDIF output using board attached to I2S bus?

Sat Nov 05, 2011 1:18 am

Yeah, that's where I've seen the mention of I2S being present.
But I'd like to see the connector pinouts, with identified signals.
It should be in the Wiki, as the board is done...
Do you Pi?

Willakan
Posts: 9
Joined: Mon Oct 31, 2011 3:49 pm

Re: 24 bit/96 khz S/PDIF output using board attached to I2S bus?

Sat Nov 05, 2011 2:57 pm

Whilst the HDMI audio output is supposedly quite good, the problem there is separating the audio from the video - few dedicated stereo DACs accept an HDMI input. The only products that could "strip out" the audio signal I've seen were rather expensive.

carlosfm
Posts: 132
Joined: Fri Oct 21, 2011 3:23 pm
Location: Lisbon, Portugal

Re: 24 bit/96 khz S/PDIF output using board attached to I2S bus?

Sat Nov 05, 2011 3:44 pm

There are HDMI converters which provide S/PDIF output (and even VGA) but they are not exactly cheap either, I mean... it costs more than an R-Pi.

Like this:
http://www.ebay.co.uk/itm/HDMI.....4cf731570b
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