Useful Links

Essential reading, or not...

References

ffmpeg.exe : This is used for MP3 conversion, but it can be used to convert just about anything to anything else. For video processing too.
https://www.ffmpeg.org/about.html

flac.exe and metaflac.exe : For FLAC file handling.
https://xiph.org/flac/

LAME MP3 Encoder : For MP3 conversion.
https://lame.sourceforge.io/

Ogg file format
https://xiph.org/ogg/

FLAC and Ogg codecs : Install these so Matt's Music Player works with FLAC and Ogg files.
Install 'opencodecs_0.85.17777.exe' or later
https://www.xiph.org/dshow/

FreeDB database : The freeDB database was discontinued in May 2020, but...
https://en.wikipedia.org/wiki/CDDB : The original CD database, later became freeDB
https://en.wikipedia.org/wiki/freedb : About freedb, still supported by gnudb.org
freedb.howto.txt : Original freeDB developer documentation
Several servers continue to support freeDB, such as...
https://gnudb.org/

MusicBrainz : Open music encyclopedia
https://musicbrainz.org/
https://wiki.musicbrainz.org/History:FreeDB_Gateway : MusicBrainz no longer supports FreeDB
https://wiki.musicbrainz.org/Development : About the new MusicBrainz API

AcousticBrainz : The acoustic characteristics of millions of tracks. MuMan uses this to get the BPM values.
https://acousticbrainz.org/

GetSongBpm : The largest database of beats-per-minute in the world. MuMan also uses this to get the BPM values.
https://getsongbpm.com/

Discogs : Music database and marketplace. Research, buy and sell almost every CD and album that's ever been produced.
https://www.discogs.com/
https://www.discogs.com/developers : About the Discogs API

Broadcast Wave Format (BWF) Specification : WAV files that can store > 4GB (but still don't support UTF-8?)
https://tech.ebu.ch/docs/tech/tech3285.pdf

RF64 An extended file format for audio
https://tech.ebu.ch/docs/tech/tech3306v1_0.pdf

ID3 Tags in MP3 files : MuMan can read all versions of the MP3 tags (even corrupted tags which other apps cannot read), but it writes ID3v2.2 (ISO or UTF-8 characters) and ID2v2.1 tags (ISO only) to MP3 files which it creates.
https://mutagen-specs.readthedocs.io/en/latest/id3/id3v2.2.html
This is the original site, but it seems to be down (Internal Server Error)
https://id3.org/ If still down, try the archive https://web.archive.org/web/20221224181120/https://id3.org/

WavPack file format (.wv) : WavPack is a completely open lossless audio compression format, which also has a 'hybrid' lossy compression mode.
https://www.wavpack.com/

Hydrogenaudio Knowledgebase : A wiki-styled resource containing everything you need to know about digital audio technology.
https://wiki.hydrogenaud.io/
Here you can find amazing things like the APEv2 information tag specification.

Isolation Transformers - WARNING!

An isolation transformer is often recommended when working with mains-powered electronics - but if you use an isolation transformer, then YOUR SAFETY SWITCH* WILL NOT OPERATE if you accidentally touch a live part of the circuit! Most of the time you will be far safer WITHOUT an isolation transformer.

* safety switch = residual current device RCD/RCCB, earth leakage circuit breaker ELCB, ground fault interrupter, etc. I use a Hager ACA910C Residual Current Circuit Breaker RCCB, which switches off with a 10mA leakage to earth.

Everyone who works with mains-powered devices should read this article.
https://sound-au.com/articles/iso-xfmr.htm

LTspice Simulator and Electronic Design

To learn about the LTspice simulator from Analog Devices, I recommend watching the YouTube video series by FesZ Electronics. He also has many other videos which go into very esoteric details about almost every aspect of electronic design.
https://www.youtube.com/playlist?list=PLT84nve2j1g_wgGcm0Bv3K4RSl2Jdjsey

https://www.youtube.com/@FesZElectronics

Microcontrollers

Wilderness Labs
A Colorado company producing amazingly small and powerful single board computers programmed in C#! With WiFi coprocessor, Bluetooth, file system, web server, etc. all for $45. Programmed in C# using Microsoft Visual Studio. Check out their "F7 Feather", a beautiful device.
https://www.wildernesslabs.co/
https://github.com/WildernessLabs

GHI Electronics
C# on a chip. Powerful microcontrollers with their own TinyCLR operating system, and just about everything else you can think of. Also programmed in C# using Microsoft Visual Studio. The "FEZ Duino" is pin-compatible with the Arduino. These are great!
https://www.ghielectronics.com/

Here's one you can get for CHF4.50, the ESP32-S2 mini, a 32-bit microcontroller with very fast WiFi, programmed in C++ using the Arduino IDE.
https://www.espressif.com/sites/default/files/documentation/esp32-s2_datasheet_en.pdf

Also check out the Arduino Nano 33 Sense Rev2, it has almost every sensor on it you would ever need...

Other interesting stuff

Programmable Logic Controllers (PLCs) are history : Check out the competition...
https://revolutionpi.com/revolution-pi-series
https://store.arduino.cc/pages/professional

OBS Studio : Excellent free software for video recording and live streaming.
https://obsproject.com/

hifiengine : The HiFi Engine Library has images, specifications and reviews for thousands of audio components. This includes user manuals, original service manuals and circuit diagrams, so when your favourite amp blows up, you can fix it yourself!
https://www.hifiengine.com/

C# : Beautifully crafted linear and curve-fit algorithms in C#, from Rod Stevens' C# Helper. Very useful for sensor calibration.
http://csharphelper.com/howtos/howto_polynomial_least_squares.html
http://csharphelper.com/howtos/howto_linear_least_squares.html

Neon Lamps : Ancient arcane technology, but it's great! Here you will find everything you need to know, all in one place.
https://www.giangrandi.org/electronics/neon/neon.shtml

Tom Nelson Podcasts : Interviews and presentations on climate and energy by top-level scientists. Scary stuff, if you're a Warmist.
https://www.youtube.com/@tomnelson2080/videos

Climate Change Data : Climate change information needs to be both accurate and undistorted, and analysis unemotional. This site does just that.
https://www.climate4you.com/

Electron Tubes and Valves : Databases used by Matt's Thermionic Valve/Electron Tube Analyser (in development)
http://www.dl7avf.info/charts/roehren/index.html
https://frank.pocnet.net/

Reading old floppy discs : Digitize your old floppies now, before they disintegrate or are demagnetized by a magnetic storm!
The Greaseweazle adapter connects a floppy disc drive to your computer via USB. Supports 3.5", 5.25", and 8" with a 50-to-34-pin adapter (e.g. FDADAP). You can read/write floppy disc images in almost any format: PC, Amiga, Amstrad, DOS, CP/M, DEC PDP etc.
https://github.com/keirf/greaseweazle/wiki : Keir Fraser's Greaseweazle wiki, user manual and software tools
https://www.kryoflux.com/ : Another USB floppy adapter, much more expensive than the Greaseweazle but has more sophisticated hardware

CP/M and DOS
This was state-of-the-art when I first started out...
https://www.sydneysmith.com/wordpress/run-cpm/ : CP/M 2.2 emulator running on Windows
https://www.sydneysmith.com/wordpress/z80emu/ : Browser-based Z80 emulator, boots CP/M from a disk image
https://www.retrotechnology.com/herbs_stuff/drive.html : Everything you will ever need to know about floppy disks, by Herb Johnson
https://www.dosbox.com/ : Cross-platform MS-DOS emulator, runs on Windows, Linux, Mac
http://www.freedos.org/ : Free DOS-compatible operating system, boots from CD or USB

Shelly, low cost WiFi/Bluetooth controls/sensors with built in web servers

https://www.shelly.com/en