Re: Multiplexing and mixing


"Bob.Jones5400@xxxxxxxxx" <bob.jones5400@xxxxxxxxx> wrote in message
news:81e96a71-cdd1-4f33-b72c-e9db2a11da91@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
I want to design a system, unless something similar exists, that
multiplexes digital audio signals but also allow for mixing of those
signals in arbitrary ways. This should be relatively cheap because I
want to use a lot of them.

The signal is arranged Sample1_audio1, sample1_audio2, etc...

Where a sample is n bits with some way to determine when a new sample
happens(I guess another line to signal the new bit or a serial like
protocol with start and stop after a "frame").

In any case it should not be difficult to "mix" to signals. I would
just extract a sample, multiply it by a the "mix" value, and add it to
a some a buffer.

But how difficult will this be to implement using discrete components
(IC's but not fpga's or uP's)? The number of signals is fixed around
20(the more the better). The audio rate is ~200khz @ 24-bit. 200khz is
over sampling so please don't whine about the human ear not being able
to hear above 20khz. This requires about 5Mhz per audio signal.

Once the signal's are mixed the new mixed signal is added to a slot in
the "bus"(it will replace one of the slots as designated by the user).

If this is easily implementable in an fgpa and doing it "discretely"
is just as costly then I suppose it is the better option. I'm just not
quite sure...




Something like this. There may be a dsp that will do the job. You do need to
add a register for each input channel level at each output. If you want
analog output you need some dacs. You need all of the inputs on each
processor. The number of outputs on each processor is limited by processing
speed.A regular processor could also be used but would probably be severely
limited as to the number of inputs. You could also build a microsequencer to
run the system.

Bob


.

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