Something Unreal

Up to 15 notes at once on an Arduino using no timers! Well, the quality drops a lot as the number of playing notes increases, but still!

[Watch in HD]

This is a demo of a MIDI synth I’m developing for the Arduino. Its sound is currently very basic – it has no concept of different instruments, can only produce square waves and noise, and each MIDI channel can only be at one of 3 different volume levels. It has no fixed sample rate, and is always producing a new sample as quickly as possible, which is slower when more notes play at once (in practise, the sample rate ranges from about 20 KHz down to about 6 KHz).

It supports pitch-bends, modulation, monophonic/polyphonic MIDI channel mode, and some percussive notes. It also recognises some sysex messages, including GM/GS/XG “reset” messages and GS/XG messages to set a MIDI channel’s percussion mode.

To use the code yourself (hardware info):

If you want the Arduino to accept MIDI data from “real” MIDI hardware (through a MIDI socket), you’ll need to build a circuit with an optocoupler and connect that to the Arduino’s serial RX port, and change #define UseRealMIDIPort False to #define UseRealMIDIPort True (this affects the baud rate used). Due to laziness, while testing, I used a program called “Hairless MIDI<->Serial Bridge” and the virtual MIDI cable driver “MIDI Yoke” to send MIDI data straight over the Arduino’s USB serial connection, instead of building the proper circuit.
The code controls one “port” on the Arduino (a group of 8 pins determined by the specific Arduino board model), which connects to an 8-bit DAC (a simple R2R resistor ladder) to give an 8-bit audio output. I’m using port C on the Arduino Mega, because that neatly corresponds to digital pins 37 (LSB) to 30 (MSB), but it may work on other Arduino boards as long as there is a port where all 8 bits are mapped to digital pins, with minimal changes to the code. The output port (PORTAudio and DDRAudio) would need changing to one consisting of 8 usable pins, and the maximum number of playing notes at once (NumSoundChans) could either be reduced (will save CPU time and memory) or, in the case of the Arduino Due, increased.

You can download the code for the current version here (13.2 KB). You will also need the Fast Division library (info). Note that the code includes most of the above hardware info in the form of comments. =)

P.S. The MIDI in the video is being played on MIDITester. I did not make the MIDI, and I don’t know who did. Please, people, at least credit yourself in the metadata ;_;

I’m working on an Arduino MIDI synth, and just tonight, I tried to add support for complex wave shapes (previously, it was only square waves and noise). Since I’ve now got enough working to be able to listen to these tiny (8-sample) lookup tables for different waveforms, I thought I’d make this video to show what they sound like. =)

(Also, I finally found a good use for block Unicode characters!)

[Watch in HD]

This update fixes a bunch of bugs and issues, and improves on what is saved between runs. As always, full details of changes are below, but please make sure that you check the details of which settings are now saved between runs to avoid any surprises, and because it has affected a couple of command line parameters.

You can download this new version here (7.82 MB).

(more…)

I made a program to send pitch-bend messages to Bawami (my MIDI synth) based on the strongest reading out of the X/Y/Z axes of the gyroscope on the GY-87 sensor board, via an Arduino. Gently moving the sensor makes for a really natural-feeling control for vibrato, allowing really subtle (or not-so-subtle) pitch changes.

[Watch in HD]

I was able to get readings from the board to Windows at a stable speed of 400 Hz, but to avoid spamming too many MIDI messages (a problem if sending them outside the computer to some hardware synth), the pitch-bends are “only” being sent at 100 Hz. =P

The GY-87 also has X/Y/Z accelerometers, but these were way too sensitive to orientation to be convenient to use as a controller. Gravity is always pulling down on one axis, so if you tilt the sensor then it massively overwhelms the readings that you actually want (the ones caused by moving the sensor around). The best use I could get from them was tracking the maximum difference between 2 points in time and sending that as a MIDI message, which basically just made it respond to vibrations (and only made positive numbers). The gyros naturally only detect changes, so the readings centre around 0 and go negative when turning in one direction and positive in the other, ideal for vibrato.

This is a tiny update which simply fixes the checkbox to enable/disable responding to MIDI channel coarse/fine tuning messages, on the “MIDI params” tab of the config window, so that it actually has an effect. Previously, Bawami always responded to those messages even if the checkbox was unticked.

You can grab this fixed version here (7.80 MB).

This is a big update which fixes a bunch of bugs, especially ones related to the PC speaker, and graphical mistakes. A new internal tuning system means Bawami now supports a big range of tuning messages (their effects can combine together!), plus there are a few new instruments and tweaks to existing ones.

Some of the MIDI Tuning Standard messages are quite advanced, and you’d typically use some other scale-related software to generate the SysEx messages rather than hand-crafting them, but they mean that Bawami can now play with tuning other than equal temperament, or different scales entirely (e.g. Arabic).

You can grab this new version from here (7.80 MB), and view details of all the changed stuff in the full post, below:

(more…)

This biggest update ever to my MIDI software synth contains dozens of bug- and crash-fixes, improvements to live MIDI input, and a big new feature for instruments called “multi-osc” (explained below), which many instruments now take advantage of! It’s stable when clicking “Apply” to restarting the sound system, which often caused crashes in the past, and there are a couple of new features to do with overriding controls. Also, one particular system file (included since a long time ago) is now correctly checked / set up when Bawami starts, which may fix Bawami not being able to start for some people. All these improvements mean that Bawami has grown to version 0.7!

The new “multi-osc” feature for instrument files allows one note to trigger more than one sound channel, massively improving the sound of some instruments. This opens the door to having a proper Fifths instrument, octave basses, octave-stacked strings, detuned Honkey Tonk, better organs and more! Of course, I updated lots of instruments to take advantage of this, and added new GS instruments whose sounds simply weren’t possible to generate before. Multi-osc is enabled by default, but can be disabled if you want to keep CPU usage as low as possible (if you really hate the new sound, you can replace all instrument files with those from the previous version, or have fun editing them yourself!).

You can grab this shiny new version from here (7.79 MB), and view the full post to see exactly what’s changed, below:

(more…)

I started playing around using the melody and chord progression that a huge number of people created together at CrowdSound, and ended up making this little arrangement for Bawami, my MIDI synth. It took a few hours over 3 nights.

CrowdSound is a site where people were given a chord progression and song structure, and were then allowed to vote note-by-note to make a melody. It’s an experiment to see if lots of people can work together to gradually make an entire song by voting on many tiny additions. Since people are making remixes already, I decided I’d try, too.

[Watch in HD]

As of the 15th of August 2016, only the melody is complete, so I imported the MIDI of the melody (from here) into Sekaiju (the MIDI editor I use). From there, based on the chord progression, I made tracks for bass, percussion, overdriven and acoustic guitar parts, 2-part pad and a portamento synth sequence to liven things up a bit. Then I decided on how I’d switch between the various backing parts so they weren’t all fighting for the spotlight at the same time. After that, I changed the velocities of all the melody notes (since I’m using a velocity-sensitive lead instrument on Bawami), to make it sound less annoying and repetitive and to complement the beat. I also shortened some long notes (which is within CrowdSound’s rules for arranging) to let the lead stop for breath every now and then, added modulation (vibrato) sparingly, and decided to somtimes pitch-bend from one note to another during the conclusion instead of instantly jumping (I think this should be allowed, because a real human voice would have to do this all the time =P).

In keeping with the openness of CrowdSound, you can download my MIDI (designed to be played on Bawami rev.132 or later) here. It uses several GS “variation” instruments, so it will sound worse on GM synths. It also uses an instrument (12-string Guitar) which is not present in Bawami rev.131, the currently-released version, but it should still sound fine on that version (it’ll fall back to the “Acoustic Guitar (Steel)” instrument). That, along with many other changes, will be in the next version I release!

This MIDI is playing on BaWaMI, which is a freeware, retro-sounding MIDI synth that uses subtractive synthesis. I’ve been working on it every now and then since 2010. You can find out more (and grab the latest version) here (click its title to get to the download page).

The 3D scrolling view of notes is MIDITrail.

Here’s my MIDI software synth Bawami doing its best to even keep responding while trying to play TheSuperMarioBros2‘s black MIDI “Arecibo“. The left view shows how it’s processing every MIDI message. Not shown: About 5 minutes of Bawami loading the 12MB MIDI file hideously inefficiently (tempo changes make it even worse).

[Watch in HD]

This problem of my player stopping responding when maxed out is something I need to (re-)fix. I fixed this a long time ago (probably before releasing Bawami), but broke it again afterwards somehow, also a long time ago now… As always, the most recent version of Bawami can be download here (also check the most recently tagged posts to see recent changes).

TheSuperMarioBros2 have made a lot of great black MIDIs that are often fun to stress-test MIDI players with. You can see lots playing at their channel (they also provide download links for the MIDI files). However, Bawami’s loading of MIDIs is inefficient, so I’d recommend not trying to torture it with black MIDIs too much. I also suggest unticking “Loop” so that, if it stops responding during playback, it’ll eventually start responding again at the end.

This is a small update which fixes OGG file rendering, and a couple of other superficial things.

• Fixed tabbing order of controls on “Mod shape” tab of the config window.
• Writing OGG files works again – I accidentally removed a file needed by the OGG encoder in revision 130. Users who extracted revision 130′s folder over revision 129′s would not have experienced the problem.
• Stopped warning about buggy controls from being displayed on the “MIDI params” tab of the config window, since it’s no longer true.

You can grab the new version from here (7.87 MB)!