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View Full Version : SB2: A couple of questions and a suggestion



Mike Hartley
2005-03-09, 19:41
Very, very cool. I work in the tech field....voip and call center stuff primarily....and I have got to say that you guys have an extremely capable (barring any hideous bugs I find in the new box I'm about to order ;-) )and innovative design team for your proprietary side. You seem both technically capable and focused on open communication with your clients. That's pretty rare these days. That coupled with the open source side is really a nice mix. Please keep up the good work on BOTH fronts. Thanks for the info.

-----Original Message-----
From: Sean Adams [mailto:sadams (AT) slimdevices (DOT) com]
Sent: Wed 3/9/2005 7:42 PM
To: Slim Devices Discussion
Cc:
Subject: Re: [slim] SB2: A couple of questions and a suggestion





> A couple of questions regarding the design. First, where did you guys
> get the idea of doing all of the DSP work in software?

Mike,

Doing all the DSP in software (as opposed to fixed-function chips) is
more difficult but it's the right thing to do. Generally a/v products
are using less and less specialized hardware for signal processing,
because general purpose processors are now so cheap.

> Is this yours from the ground up?

Vidur did most of the DSP work, including porting mp3 (based on
Underbit MAD) and getting all the new bufferin, crossfading, and
visualizers in place. I did the logic design and the software s/pdif
driver.

> And second, you talk about the seperate data paths for the analog and
> s/PDIF. When you say you can output the digital stream to an AV
> receiver and a seperate rendition to the analog outs, where would the
> seperate data stream come from?

S/PDIF has an extension for compressed bitstreams. This is how DVD
players send 5.1 audio to a receiver over s/pdif. Our CPU could pass
the compressed 5.1 bitstream out the s/pdif, and simultaneously
decompress and feed a stereo signal to the DAC.

> Also, rather than seperate renditions of the same file, you might want
> to consider the option of sending one title to the analog and one to
> the digital.

Yep, another possibility. You could do a laser show by driving a pair
of galvanometers off the analog outputs while playing the audio out of
the s/pdif. :)

> I know there are many interface challenges to this suggestion, but
> many AV receivers have zone two capability that allows you to listen
> to different content in each zone and in most that capability is
> limited to analog input. This split would allow you to play different
> titles in zone one and zone two using one receiver. In the current
> scenario, you would have to listen to the same content in both zones.

We're all for suggestions...