[lug] Ethernet sound card

[Alan Robertson]

Peter Hutnick wrote:
> I seem to have utterly failed to communicate.
> 
> A picture is worth a thousand words they say.  See
> http://hutnick.com/network_sound_card.jpg
> 
> Note that there is no processor.  Note that there is a DAC (and NOT a
> DSP).  Note that some magic happens on the non-straight line between
> Ethernet Controller and Buffer and some more (lesser) magic happens
> between Buffer and DAC.
> 
> The first magical thing is that (raw) Ethernet frames with the device's
> MAC are picked up (or, I think more properly, aren't dropped) and are put
> in the (FIFO) buffer.
> 
> The second magical thing is that the buffer is "read" out to the DAC at
> the right rate (150kb/s?  1x CD speed, anyway).  The DAC doesn't know that
> this isn't output from a CD's laser.
> 
> I don't think that either of these things are insurmountable (to, say, a
> third year EE student) or requires a microprocessor.

Protocol - TCP retransmission, etc?

Buffer management?

Security?

Configuration?

A microprocessor with memory and NVRAM doesn't add much more than $10 to the 
cost (if that).  All these features need a processor, and all of them are 
needed.

If the whole problem is that your stereo is in one room and your computer in 
another, then controlling it through your computer (which you've already 
said isn't close by) would be a problem.

Luke's suggestion is better.  Just use cat5 wire and a pair of codecs over 
the wire.  You can buy these easily - and a pair of high-quality codecs is 
in the same price range as the Auditron - because of low market volumes.

What you can buy the parts for is quite a different matter from what you can 
buy the device for.


	-- Alan Robertson
	   alanr at unix.sh