
Geometric intuition for digital audio filters - khiner
https://karlhiner.com/jupyter_notebooks/intro_to_digital_filters
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anyfoo
Julius O. Smith's books are excellent, easily ranking up amongst the best text
books I've always read. It's always a good sign if I look forwarding to
continue reading as if it were a novel...

You can actually read them for free online:
[https://ccrma.stanford.edu/%7Ejos/Welcome.html](https://ccrma.stanford.edu/%7Ejos/Welcome.html)
I picked up printed copies on Amazon regardless, both because I wanted to
support the author after reading almost a full book online, and because I
sometimes prefer reading a physical textbook (the "spatiality" somehow helps
me remember better).

I'm a Software Engineer without any background in signal processing (or
audio), and stumbled upon his books when an FPGA hobby project of mine
involved a simple audio pipeline for which I wanted to do some sample rate
conversion. Since then DSP has become a hobby on its own.

I actually read the "Digital Filters" book (the second in the series) first,
before reading the first book about DFT fundamentals, and it worked pretty
well.

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snaky
And to all that said, all the pages and books on his site ain't require
JavaScript, unlike link in topic.

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khiner
Are you refering to my site or JOS’s site? Can you elaborate please?

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snaky
JOS's site doesn't require JavaScript to read the content. Your site requires
JavaScript to read the content.

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khiner
Yes, gotcha. My whole site is a react app with a lot of MathJax formatting and
some posts center around JavaScript animations. But mainly the holdup is that
it uses async-loaded code-splitting techniques to keep initial page loads
down. It would be a big challenge to make it friendly without a lot of dynamic
language help. Apologies. (Although I will think about how to make text-only
content available as I agree with the idea that JS-only is unnecessarily
restrictive when most of the actual content is text and images.)

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mrob
Good article, although in reality removing 60Hz hum isn't so simple, because
it's never a pure sine wave. You get harmonics too, and the ear is more
sensitive to those higher frequencies so they can be a problem even at lower
amplitudes.

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khiner
That is a really good point. “Remove” is a pretty flippant word to use in this
context. I’ll update, thanks :)

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bsder
The only gripe I always have with digital filtering texts is everything is
always around "normalized".

The problem is that my equipment always reports things in "real" time and
frequency.

Having to make this jump always confuses students horribly.

Look at all the grief that Monty got about why not 24/192 downloads. He
actually had to create a video about it:
[https://xiph.org/video/vid2.shtml](https://xiph.org/video/vid2.shtml)

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j7ake
This is an excellent exposition of the topic with nice animations. I look
forward to more of these.

How long does it take to work through the textbooks ?

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khiner
Thanks, glad you enjoyed it! Lately I’ve had a break from full time work, so I
could dedicate all my time to them. This one took a little over three weeks I
think, which is pretty typical. His next book, Physical Audio Signal
Processig, is a pretty huge tomb of a textbook so I imagine it would take much
longer even with full time dedication. I started it but have to put it down
for a bit to look for work. Even with this Filters book it was easy to get
stuck on a single problem for most of the day.

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jarmitage
This is brilliant, thank you!

I see JOS' other texts in the repo, are you aiming to complete those too?

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khiner
Thanks! I have a similar post for Mathemeatics of the DFT, and I’ve started
Physical Audio Signal Processing, but currently distracted by other software
projects. I love the books, can’t wait to get back to them.

