[Tfug] Audio client

[Harry McGregor]

Bexley Hall wrote:
> Seasoned Greetings,
>
> OK, I have just about finalized my hardware design for
> these little "audio clients".  I'd appreciate any comments
> folks might have (esp folks who own things like Audiotrons).
>
> - 10/100 interface
>   
I would recommend both an RJ45 and a 110 punch block.  RJ45 for patch
cables, and 110 for inwall installation.
> - ~64KB RAM
> - ~128KB Flash
> - dual 24 bit D/AC's
> - ~10W stereo amplifier (1x10 or 2x5)
> - PoE
>   
802.3af or some hack job?
> - "line out" at the expense of amplified output
>
> Note there is *no* user interface!  The goal is to make the
> audio gear in the house "become invisible" (so why design a
> box with a display and controls that will then need to be
> *visible* in order to be usable??).  This also greatly reduces
> cost (I'm probably in the $25 range for "one off" quantities)
> and size (ideally, I can build this *into* a speaker and
> never have to see any of it!)
>
> My plan is to use a simple codec and (in my case) convert all
> of the media files to that form so they can be served directly.
> Or, write a transcoder that resides server-side and effectively
> does the same thing.
>
>   
10/100 has lots of bandwidth, just use PCM/WAV, no need for compression.

You don't have to transcode, just "play" the file, as your target is
uncompressed audio.

Even 24bit 96Khz audio is under 5mbit/sec

More "normal" / CD quality audio is 16bit 48KHz and is about 1.5Mbit/sec

Both of these should easily fit on 10/100 ethernet.

> Note that simplifying the client also makes it easier for people
> to hack the box -- since you can hack the server side instead of
> having to deal with the actual target (cross development, etc.)
>
> And, it lets folks decide how *they* want to talk to the box
> instead of living with someone else's (e.g., me) idea of what 
> a user interface should entail.
>
> Of course, this also means people will have to make an
> *investment* (time) in that -- instead of just buying it off
> the shelf!  :>  (Free software, not free lunches!)
>
>   
Sounds very cool, we did a bunch of work with the Channel Vision's A-Bus
products.

Worked quite well, but very expensive.

Having the low power amp in the face plate was great.  Wired speakers to
the wall plate in the room, and not back to a wiring closet.  Speaker
wire adds up quickly, cat 5 is cheap.

These units use Cat-5 to the unit, and have both an RJ45 and a 110 block.

http://www.hometech.com/hts/products/audio/whole_house/cv_abus/index.html


                               Harry


> --don
>
>
>       
>
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