Subject: Re: [linux-audio-dev] Software filter engines for high end audio and now DSP's
From: Anders Torger (torger_AT_ludd.luth.se)
Date: ke helmi 16 2000 - 15:37:05 EST
On Wed, 16 Feb 2000, you wrote:
> That is why I am still dreaming about an "audio operating system",
> ( MuCoS) which would provide an abstraction layer to run your
> native audio processing components on top on a high performance OS.
> (in this case Linux).
How about RT Linux? It exists today.
> The only hurdles for useful native processing until now were:
> - CPUs too slow , (this is changing because we are approaching the GHz
> frequency range, plus CPUs are more and more equipped with DSP-like instructions
> ( MMX etc) which will speedup greatly the DSP processing.
What I have noticed when I made the WFIR and FIR engines, is that one wants a 64
bit processor. The reason is that 32 bits is not enough as accumulation
register. 56 bit is common in DSPs, and is the least one need. It is possible
to accumulate to 64 bits on the IA32, but then you need to use two 32 bit
registers and a cumbersome clock-cycle eating way of adding numbers. When it
comes to MMX, it is only suitable for 16 bit data, making it irrelevant for
high end use, I thought at first. But with some tricks it is possible to use it
anyway while maintaining signal quality, however the input is limited to
16 bit. But 24 bit @ 96 kHz is anyway today a too high data rate for most real
time applications running on standard hardware.
By the way, has anyone tried clustering machines (preferrably Linux boxes) to
do real time audio processing? I'm especially interested in FIR filters with
more than 15000 taps. It must be a problem to keep latency low in these
systems. I have thought of the idea to use digital soundcards for data transfer
between the machines in the clusters, must be perfect for low latency hard real
time data transfers [at limited rates]. However multichannel digital sound cards
are a lot more expensive than network adaptors, so I guess it is just a wierd
idea :-)
-- /Anders Torger"Lascia la spina, cogli la rosa"
This archive was generated by hypermail 2b28 : pe maalis 10 2000 - 07:23:27 EST