Audacity’s FFT Filter and the Equalization effect
I will take a close look on Audacitys FFT Filter.
I’m still learning how to use all features.
I did FFT with Hypersignal
meanwhile I have discovered some nice pages I have previously
only seen in music magazines.
I was there many many years ago and I have seen an introduction
to what at that time was possible.
some nice introductory topics
the standard DSP textbooks
My personal preferred white paper
A Mathematical Theory of Communication
It is much better we agree about what DSPs can do,
most CPUs has the FLOPS required to do what a special purpose DSP
could at most ideally do few years ago.
Basically latency is for most practical applications like gaming or
video conferencing always a limiting factor.
By splitting the signal in small short time windows,
and applying some signal processing on each of these frames you get what you want.
The duration of this time windows will
always result in some kind of latency,
on a normal CPU this latency will always increase by threads and CPU load.
so striving for zero latency and claiming to be some application of FFT
is to me a contradiction.
After one time window sample has elapsed the processing can at most start.
constant latency and FFT is possible.
Zero latency and FFT plus inverse FFT is impossible.
What is neglectible latency is a personal matter.
Young persons can hear better than their parents.
only a DSP with application software and operating system
designed for real time can offer that.
If you google for fft filter marketing gimmick
you will find this
Jitter spectral extraction for multi-gigahertz signal - Design …
With marketing gimmicks pushing for higher processor … FFT. to extract the peaks and frequencies of the. sinusoidal jitters. …
ieeexplore.ieee.org/iel5/9284/29505/01337584.pdf - Similar pages
I don’t have access to the paper.
Esp in consumer oriented music for multimedia
they are often free to write anything.
inclusive FFT and IFFT.
Jitter congestion latency and round trip time is hot topics in real time gaming and
next generation network,
which could be a concert conducted over the internet.
Here is a nice podcast about post production.
some nice hardware.
discusses fft pro and contra.
Offers an alternative to FFT which I have never heard about.
Real-time FFT filtering
As an example red book specified 44.1 KHz 16 bit stereo
K at that time was 1000
In marketing it can be 2^10 = 1024
mp3 is a file format or streaming format which reduces bandwidth.
and saves file space. the same filter applied on all three signals
I feel will not give the same effect. analog (through ADC + DSP + DAC ), PCM, or mp3
The best evidence for that is aliasing.
for that we have anti aliasing filter.
Audio Critic’s Ten Biggest Lies
Shows that it exists smoke without fire.
Ideally an FFT filter is a piece of software which runs well on a DSP and uses a RTOS.
if it is not a DSP and not an RTOS the same software behaves different and does
not do what normally an FFT filter was designed to do.
This is independent of audacity, the OP had a Q about FFT in general,
FFT does not need to filter anything.
as in mp3 it does not filter anything, it simply reduces the bandwidth.
and shortens the download.