Reply by robert bristow-johnson●July 29, 20132013-07-29
i just gotta make sure this doesn't go public...
On 7/28/13 7:50 PM, Tim Wescott wrote:
>
...
>
> I thought it was very nice and polite. More polite than, for instance,
> you ever are to us.
>
oh c'mon, "ever"?
who here do i pick on? (besides the heathen heretical DFT periodicity
deniers)
oh, i guess that there are the
we-must-count-from-one-otherwise-MATLAB-would-break crowd (not too many
on comp.dsp but there were a couple, at least)
then there was those troll-kinda guys (who were they? i can only
remember E.Bob. but there were others).
i don't pick on noobs. i don't think i do.
> I wasn't sure at first if it was an open letter or a misdirect, but your
> above response does at least clarify that point.
it coulda been worse. but it's not the first time this happened. some
designer or coder should be hurt in retribution for deciding to do it
that way. death penalty might be a little harsh.
> And in case you're wondering -- this is part of the reason that I prefer
> having separate email and news clients.
i just want my life to be simple. as simple as possible. i just want
something that i can run on this mac and Google Groups became horribly
bad and eternal september doesn't do a webpage-based service (but i'm
grateful it's free and not icky in some way), it seemed that i had to
get a client to do it, and the only one i found was Thunderbird. dunno
why Apple's Mail does this dumb RSS that you can't get rid of, but it
doesn't do USENET like all of the old email clients used to do.
ya know, i used to know how product builds go (although i left it to
someone else to be the keeper of the makefile) and how version control
works, i used to be able to use the CodeWarrior and SourceSafe to build
an app (or a code resource), how to back up, commit, check-in, "push",
whatever you wanna call it.
now it's just so much more complicated when what i wanna do is just the
same as it used to be. that's like negative progress: i have to pay
more to do the same, a declining payback. but isn't that opposite of
the promise of modern computers (particularly the user-friendly
revolution that sorta came with the Mac in 1984)? the computers exist
to make my life easier, not the other way around. how come is it so
much more complicated to do anything (even a simple graphic or
something) now than it used to be?
--
r b-j rbj@audioimagination.com
"Imagination is more important than knowledge."
Reply by robert bristow-johnson●July 28, 20132013-07-28
Dear Dr. Mitra,
I've been hoping to possibly run into you sometime at a professional
conference, perhaps the IEEE WASPAA (a.k.a. Mohonk), but I haven't been
to that conference since 2001 and I haven't yet seen you at an Audio
Engineering Convention (and, admittedly, I'm not in IEEE). I am now
working for a company in Calabasas (Music Mastermind) so I hope that
someday I can meet you while I am local to USC.
I was sorta exploring the dsp.stackexchange.com site and I came upon a
short monograph attributed to you called "Applications of Digital Signal
Processing". I don't know if this is part of an existing book in print,
or is on the way to print. I found the link to at the University of
Vermont site, which is quite coincidental since Burlington Vermont is my
permanent address and the prof listing it (Gagan Mirchandani) is someone
I am acquainted with.
The work appears useful and valuable to me, and I immediately noticed
Sections 5 and 6, which are about what I do for a living and where I
also have published. In fact, one old paper I have written (that later
resulted in the Audio EQ Cookbook) called "The Equivalence of Various
Methods of Computing Biquad Coefficients for Audio Parametric
Equalizers" (long title) came from a paper by Dana Massie that came from
your Regalia and Mitra paper about APFs and the bell-shaped parametric
EQ. I have also written about wavetable synthesis ("Wavetable synthesis
101, a fundamental perspective") which is what I want to write you about.
I don't believe previous authors, nor even the seminal authors
themselves, would identify or categorize the Karplus-Strong algorithm
for generating harmonically-rich musical tones as "wavetable synthesis".
there is a delay-line with feedback, and so also do reverb algorithms
have delay lines and feedback, but they are not "wavetables".
Wavetable Synthesis is more about what the Palm PPG (
http://wolfgangpalm.com/ ) and Waldorf software synthesizers have been
doing. Another, more local example is the Prophet VS synthesizer (Dave
Smith Instruments, also the creator of MIDI), There has been, nearly 2
decades ago, a confusion about the meaning of "wavetable synthesis"
because of Creative Labs and the Soundblaster sound card that label
their sample-playback-and-looping rendering of tones as "wavetable
synthesis". It took some years and some editing of certain blogs and
sites (including Wikipedia) to set the record straight that simple
soundfile playback (even with sample interpolation and playback speed
adjustment for changing pitch) with a single loop at the end is not what
the original "wavetable synthesis" had been. It was used as a marketing
term by Creative Labs.
But neither is the Karplus-Strong technique wavetable synthesis. I
would judge that Karplus-Strong more closely is categorized as a simple
form of Physical Modeling Synthesis, and I think that Julius Smith would
agree.
Wavetable Synthesis is similar to the pedestrian
sample-playback-and-looping technique, except that in wavetable
synthesis, it is virtually always in looping mode. And the loops are
always exactly one period or cycle of the quasiperiodic tone. Yes,
there is at least one paper (by Andrew Horner and one of his students)
combining Wavetable and an unrepeated attack waveform of the instrument,
but in wavetable synthesis, the tone spectra morphs from one line
spectrum to the next simply by cross-fading from one wavetable to the next.
If you want, I could help you describe what is fundamentally involved
with Wavetable Synthesis, how it relates to sample-playback-and-looping
and also to Additive Synthesis (wavetable synthesis can be thought of as
a way of performing additive synthesis of quasiperiodic tones where the
inverse Fourier transform is done in advance and not at the real-time
generation of the tone, the waveforms are pre-computed).
Also, if you want, I would be happy to meet with you in person at your
convenience (say at your office or even over food somewhere) since I am
not local (I am lucky to have found a little place to live in Malibu, by
the Backbone trail).
Although I haven't written a monograph myself, I have participated in
some other efforts including Principles of Digital Audio by Pohlmann and
also that large compendium by Mark Khars and Karlheinz Brandenburg (Dana
Massie had a chapter on "Wavetable Sampling Synthesis").
I can also be contacted by cell phone: 802/310-4096 if you would want.
Best regards,
Robert Bristow-Johnson
--
r b-j rbj@audioimagination.com
"Imagination is more important than knowledge."