[LAU] zedboard fpga dev board and linux audio

[Simon Wise]

On 02/02/13 04:07, Kelly Hirai wrote:
>

> fpga seems a natural way to express in silicon, data flow languages like
> pd, chuck, csound, ecasound. regarding the stretch, the idea that one
> could code in c or c++ might streamline refactoring code, but i'm still
> trying to wrap my head around designing graph topology for code that is
> tied to the program counter register. nor do i see the right peripherals
> for sound. perhaps the g.711 codec support is software implementation
> and could be rewritten. need stats on the 8 bnc to dvi adapter audio port.

The Stretch seems to be focussed on video, the examples given to explain their 
compiler process show it picking reasonably complex mathematical expressions 
inside loops which it then converts to logic with registers in and out, I guess 
probably duplicated logic if possible. That way the critical inner loops are 
optimised. With video and image recognition stuff it could work very well, there 
is lots of iterating over rows of pixels with convolutions and stuff in those 
algorithms.

>
> on the xlinx side, would you really have to hack it in vhdl? rewriting
> opcodes / function blocks in vhdl could be rewarding but still, that
> would be the end of my time.

The Xilinx software claims to include a large library of elements to use, not 
sure what areas they would cover, and there seems to be some DSP stuff too, 
perhaps at extra cost. The example application on the website is building 
automotive sound systems ... which would involve filters, eqs, codecs, radio 
decoders and so forth.

But the open source stuff seems pretty serious as well, with NASA and the 
European Space Agency featuring as contributors. They probably use a lot of DSP, 
in many frequency ranges, so maybe they have contributed more than just their 
CPU designs?

For serious audio the large supply of GPIO pins connected to the FPGA all on the 
chip seems to fit a physical control surface with lots of inputs and extremely 
low latency very well. And as you say the dataflow languages seem to fit the 
FPGA type of machine very well.

But all of this is serious, time consuming, work of course.


Simon