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@ -7,24 +7,33 @@ A cross-platform modular software synthesizer for small intros, forked from
Summary
-------
Sointu is work-in-progress. It is a fork and an evolution of [4klang](
https://github.com/hzdgopher/4klang), a modular software synthesizer intended
to easily produce music for 4k intros-small executables with a maximum
Sointu is work-in-progress. It is a fork and an evolution of
[4klang](https://github.com/hzdgopher/4klang), a modular software synthesizer
intended to easily produce music for 4k intros-small executables with a maximum
filesize of 4096 bytes containing realtime audio and visuals. Like 4klang, the
sound is produced by a virtual machine that executes small bytecode to
produce the audio; however, by now the internal virtual machine has been
heavily rewritten and extended to make the code more maintainable, possibly
even saving some bytes in the process.
sound is produced by a virtual machine that executes small bytecode to produce
the audio; however, by now the internal virtual machine has been heavily
rewritten and extended. It is actually extended so much that you will never fit
all the features at the same time in a 4k intro, but a fairly capable synthesis
engine can already be fitted in 600 bytes (compressed), with another few hundred
bytes for the patch and pattern data.
Sointu consists of two core elements:
- A cross-platform synth-tracker app for composing music, written in
[go](https://golang.org/). The app is not working yet, but a prototype is
existing. The app exports (will export) the projects .yml files.
- A compiler, likewise written in go, which can be invoked from the command line
to compile these .yml files into .asm code. The resulting single file .asm can
be then compiled by [nasm](https://www.nasm.us/) or
[yasm](https://yasm.tortall.net).
Building
--------
Requires [CMake](https://cmake.org), [nasm](https://www.nasm.us/) or
[yasm](https://yasm.tortall.net), and your favorite c-compiler & build tool.
Results have been obtained using Visual Studio 2019, gcc&make on linux,
MinGW&mingw32-make, and ninja&AppleClang.
Additionally, building the tracker requires [go](https://golang.org/).
Requires [go](https://golang.org/), [CMake](https://cmake.org),
[nasm](https://www.nasm.us/) or [yasm](https://yasm.tortall.net), and your
favorite c-compiler & build tool. Results have been obtained using Visual Studio
2019, gcc&make on linux, MinGW&mingw32-make, and ninja&AppleClang.
### Example: building and running CTests using MinGW32
@ -54,96 +63,122 @@ cd ..
go test ./...
```
Running `mingw32-make sointu` only builds the static library that go needs. This is a lot
faster than building all the CTests.
Running `mingw32-make sointu` only builds the static library that go needs. This
is a lot faster than building all the CTests.
If you plan to build the Sointu library for using it from the Go side, you
*must* build in the build/ directory, as bridge.go assumes the library can be
found from build/.
> :warning: **If you are using MinGW and Yasm**: Yasm 1.3.0 (currently still the latest
stable release) and GNU linker do not play nicely along, trashing the BSS layout.
See [here](https://tortall.lighthouseapp.com/projects/78676/tickets/274-bss-problem-with-windows-win64)
and the fix [here](https://github.com/yasm/yasm/commit/1910e914792399137dec0b047c59965207245df5).
> :warning: At the moment, you must have gcc (e.g. mingw32 on Windows) to build
the project. This is because cgo (the bridge to call c from go) requires gcc
compiler, and the rest of the project uses the go code to automatically build
the .asm from the .yml test cases. A solution that drops the need for CMake and
gcc is in the works; it likely involves dropping precompiled binaries for the
most popular platforms in the repository, which should also allow `go get` the
project. Regardless, it is possible to build the test cases using Visual Studio,
after building the library using mingw32. Luckily, the prebuilt binaries will be
only few tens of KB; this is a 4k synth project after all.
> :warning: **If you are using MinGW and Yasm**: Yasm 1.3.0 (currently still the
latest stable release) and GNU linker do not play nicely along, trashing the BSS
layout. See
[here](https://tortall.lighthouseapp.com/projects/78676/tickets/274-bss-problem-with-windows-win64)
and the fix
[here](https://github.com/yasm/yasm/commit/1910e914792399137dec0b047c59965207245df5).
Use a newer nightly build of yasm that includes the fix. The linker had placed
our synth object overlapping with DLL call addresses; very funny stuff to debug.
New features since fork
-----------------------
- **Per instrument polyphonism**. An instrument has the possibility to
have any number of voices, meaning in practice that multiple voices can
reuse the same opcodes. Done, see [here](tests/test_polyphony.asm) for an
example and [here](src/opcodes/flowcontrol_footer.inc) for the implementation. The
maximum total number of voices will be 32: you can have 32 monophonic
instruments or any combination of polyphonic instruments adding up to 32.
- **Any number of voices per track**. For example, a polyphonic instrument of
3 voices can be triggered by 3 parallel tracks, to produce chords. But one
track can also trigger 3 voices, for example when using arpeggio. A track
can even trigger 2 voices of different instruments, alternating between
these two; maybe useful for example as an easy way to alternate between an
open and a closed hihat.
- **Compiler**. Written in go. The input is a .yml file and the output is an
.asm. It works by inputting the song data to the excellent go
`text/template` package, effectively working as a preprocessor. This allows
quite powerful combination: we can handcraft the assembly code to keep the
entropy as low as possible, yet we can call arbitrary go functions as
"macros".
- **Tracker**. Written in go. A prototype exists.
- **Supports 32 and 64 bit builds**. The 64-bit version is done with minimal
changes to get it work, using template macros to change the lines between
32-bit and 64-bit modes. Mostly, it's as easy as writing {{.AX}} instead of
eax; the macro {{.AX}} compiles to eax in 32-bit and rax in 64-bit.
- **Supports Windows, Linux and MacOS**. On all three 64-bit platforms, all
tests are passing. Additionally, all tests are passing on windows 32.
- **New units**. For example: bit-crusher, gain, inverse gain, clip, modulate
bpm (proper triplets!), compressor (can be used for side-chaining).
- **Per instrument polyphonism**. An instrument has the possibility to have
any number of voices, meaning in practice that multiple voices can reuse the
same opcodes. So, you can have a single instrument with three voices, and
three tracks that use this instrument, to make chords. See
[here](tests/test_chords.asm) for an example and [here](templates/patch.yml)
for the implementation. The maximum total number of voices will be 32: you
can have 32 monophonic instruments or any combination of polyphonic
instruments adding up to 32.
- **Any number of voices per track**. A single track can trigger more than one
voice. At every note, a new voice from the assigned voices is triggered and
the previous released. Combined with the previous, you can have a single
track trigger 3 voices and all these three voices use the same instrument,
useful to do polyphonic arpeggios (see [here](tests/test_polyphony.yml)).
Not only that, a track can even trigger voices of different instruments,
alternating between these two; maybe useful for example as an easy way to
alternate between an open and a closed hihat.
- **Easily extensible**. Instead of %ifdef hell, the primary extension
mechanism will be through new opcodes for the virtual machine. Only the
opcodes actually used in a song are compiled into the virtual machine. The
goal is to try to write the code so that if two similar opcodes are used,
the common code in both is reused by moving it to a function.
- **Take the macro languge to its logical conclusion**: it should probably be
called an internal domain specific language, hosted within the .asm preprocessor,
implemented using loads of macro definitions. Only the patch definition is needed;
all the %define USE_SOMETHING will be defined automatically by the macros. Only
the opcodes needed are compiled into the program. Done, see for example
[this test](tests/test_oscillat_trisaw.asm)! This has the nice implication that,
in future, there will be no need for binary format to save patches: the .asm
is easy enough to be imported into / exported from the GUI. Being a text
format, the .asm based patch definitions play nicely with source control.
the common code in both is reused by moving it to a function. Macro and
linker magic ensure that also helper functions are only compiled in if they
are actually used.
- **Songs are YAML files**. These markup files are simple data files,
describing the tracks, patterns and patch structure (see
[here](tests/test_oscillat_trisaw.yml) for an example). The sointu-cli
compiler then reads these files and compiles them into .asm code. This has
the nice implication that, in future, there will be no need for a binary
format to save patches, nor should you need to commit .o or .asm to repo:
just put the .yml in the repo and automate the .yml -> .asm -> .o steps
using sointu-cli & nasm.
- **Harmonized support for stereo signals**. Every opcode supports a stereo
variant: the stereo bit is hidden in the least significant bit of the
command stream and passed in carry to the opcode. This has several nice
advantages: 1) the opcodes that don't need any parameters do not need an
entire byte in the value stream to define whether it is stereo; 2) stereo
variants of opcodes can be implemented rather efficiently; in many cases,
the extra cost of stereo variant is only 7 bytes, of which 4 are zeros, so
should compress quite nicely. 3) Since stereo opcodes usually follow stereo
opcodes (and mono opcodes follow mono opcodes), the stereo bits of the
command bytes will be highly correlated and if crinkler or any other
modeling compressor is doing its job, that should make them highly
predictable i.e. highly compressably. Done.
variants of opcodes can be implemented rather efficiently; in some cases,
the extra cost of stereo variant is only 5 bytes (uncompressed). 3) Since
stereo opcodes usually follow stereo opcodes (and mono opcodes follow mono
opcodes), the stereo bits of the command bytes will be highly correlated and
if crinkler or any other modeling compressor is doing its job, that should
make them highly predictable i.e. highly compressably.
- **Test-driven development**. Given that 4klang was already a mature project,
the first thing actually implemented was a set of regression tests to avoid
breaking everything beyond any hope of repair. Done, using CTest.
- **New units**. Bit-crusher, gain, inverse gain, clip, modulate bpm
(proper triplets!), compressor (can be used for side-chaining)... As
always, if you don't use them, they won't be compiled into the code.
- **Arbitrary signal routing**. SEND (used to be called FST) opcode normally
sends the signal as a modulation to another opcode. But with the new
RECEIVE opcode, you just receive the plain signal there. So you can connect
signals in an arbitrary way. Actually, 4klang could already do this but in
a very awkward way: it had FLD (load value) opcode that could be modulated;
FLD 0 with modulation basically achieved what RECEIVE does, except that
RECEIVE can also handle stereo signals. Additionally, we have OUTAUX, AUX
and IN opcodes, which route the signals through global main or aux ports,
more closer to how 4klang does. But this time we have 8 mono ports / 4
stereo ports, so even this method of routing is unlikely to run out of ports
in small intros.
breaking everything beyond any hope of repair. Done, using go test (runs the
.yml regression tests through the library) and CTest (compiles each .yml
into executable and ensures that when run like this, the test case produces
identical output). The tests are also ran in the cloud using github actions.
- **Arbitrary signal routing**. SEND (used to be called FST in 4klang) opcode
normally sends the signal as a modulation to another opcode. But with the
new RECEIVE opcode, you just receive the plain signal there. So you can
connect signals in an arbitrary way. Actually, 4klang could already do this
but in a very awkward way: it had FLD (load value) opcode that could be
modulated; FLD 0 with modulation basically achieved what RECEIVE does,
except that RECEIVE can also handle stereo signals. Additionally, we have
OUTAUX, AUX and IN opcodes, which route the signals through global main or
aux ports, more closer to how 4klang does. But this time we have 8 mono
ports / 4 stereo ports, so even this method of routing is unlikely to run
out of ports in small intros.
- **Pattern length does not have to be a power of 2**.
- **Sample-based oscillators, with samples imported from gm.dls**. Reading
gm.dls is obviously Windows only, but the sample mechanism can be used also
without it, in case you are working on a 64k and have some kilobytes to
spare. See [this example](tests/test_oscillat_sample.asm), and this Python
[script](scripts/parse_gmdls.py) parses the gm.dls file and dumps the
sample offsets from it.
- **Unison oscillators**. Multiple copies of the oscillator running sligthly
spare. See [this example](tests/test_oscillat_sample.yml), and this Python
[script](scripts/parse_gmdls.py) parses the gm.dls file and dumps the sample
offsets from it.
- **Unison oscillators**. Multiple copies of the oscillator running slightly
detuned and added up to together. Great for trance leads (supersaw). Unison
of up to 4, or 8 if you make stereo unison oscillator and add up both left
and right channels. See [this example](tests/test_oscillat_unison.asm).
- **Supports 32 and 64 bit builds**. The 64-bit version is done with minimal
changes to get it work, mainly for the future prospect of running the MIDI
instrument in 64-bit mode. All tests are passing so it seems to work.
- **Supports Windows, Linux and MacOS**. On all three 64-bit platforms,
all tests are passing. Additionally, all tests are passing on windows 32.
and right channels. See [this example](tests/test_oscillat_unison.yml).
- **Compiling as a library**. The API is very rudimentary, a single function
render, and between calls, the user is responsible for manipulating
the synth state in a similar way as the actual player does (e.g. triggering/
render, and between calls, the user is responsible for manipulating the
synth state in a similar way as the actual player does (e.g. triggering/
releasing voices etc.)
- **Calling Sointu as a library from Go language**. The Go API is slighty more
sane than the low-level library API, offering more Go-like experience.
@ -151,25 +186,44 @@ New features since fork
Future goals
------------
- **Find a more general solution for skipping opcodes / early outs**. It's
probably a new opcode "skip" that skips from the opcode to the next out in
case the signal entering skip and the signal leaving out are both close to
zero.
- **Even more opcodes**. Maybe an equalizer? DC-offset removal?
- **Browser-based GUI and MIDI instrument**. Modern browsers support WebMIDI,
WebAudio and, most importantly, they are cross-platform and come installed
on pretty much any computer. The only thing needed is to be able to
communicate with the platform specific synth; for this, the best
option seems to be to run the synth inside a tiny websocket server that
receives messages from browser and streams the audio to the browser.
The feasibility of the approach is proven (localhost websocket calls
have 1 ms range of latency), but nothing more is done yet.
- **Find a more general solution for skipping opcodes / early outs**. It might
be a new opcode "skip" that skips from the opcode to the next out in case
the signal entering skip and the signal leaving out are both close to zero.
Need to investigate the best way to implement this.
- **Even more opcodes**. Some potentially useful additions could be:
- Equalizer / more flexible filters
- Very slow filters (~ DC-offset removal). Can be implemented using a single
bit flag in the existing filter
- Arbitrary envelopes; for easier automation.
- **MIDI support for the tracker**.
- **Reintroduce the sync mechanism**. 4klang could export the envelopes of all
instruments at a 256 times lower frequency, with the purpose of using them
as sync data. This feature was removed at some point, but should be
reintroduced at some point. Need to investigate the best way to implement
this; maybe a "sync" opcode that save the current signal from the stack? Or
reusing sends/outs and having special sync output ports, allowing easily
combining multiple signals into one sync. Oh, and we probably should dump
the whole thing also as a texture to the shader; to fly through the song, in
a very literal way.
Nice-to-have ideas
------------------
- **Tracker**. If the list of primary goals is ever exhausted, a browser-based
tracker would be nice to take advantage of all the features.
Crazy ideas
-----------
- **Using Sointu as a sync-tracker**. Similar to [GNU
Rocket](https://github.com/yupferris/gnurocket), but (ab)using the tracker
we already have for music. We could define a generic RPC protocol for Sointu
tracker send current sync values and time; one could then write a debug
version of a 4k intro that merely loads the shader and listens to the RPC
messages, and then draws the shader with those as the uniforms. Then, during
the actual 4k intro, just render song, get sync data from Sointu and send as
uniforms to shader. A track with two voices, triggering an instrument with a
single envelope and a slow filter can even be used as a cheap smooth
interpolation mechanism.
- **Support WASM targets with the compiler**. It should not be impossible to
reimplement the x86 core with WAT equivalent. It would be nice to make it
work (almost) exactly like the x86 version, so one could just track the song
with Sointu tools and export the song to WAT using sointu-cli.
- **Hack deeper into audio sources from the OS**. Speech synthesis, I'm eyeing
at you.
Anti-goals
----------
@ -182,17 +236,20 @@ Anti-goals
VSTi2... There is [JUCE](https://juce.com/), but it is again a mammoth and
requires apparently pretty deep integration in build system in the form of
Projucer. If someone comes up with a light-weight way and easily
maintainable way to make the project into DAW plugin, I may reconsider.
maintainable way to make the project into DAW plugin, I may reconsider. For
now, if you really must, we aim to support MIDI.
Design philosophy
-----------------
- Try to avoid %ifdef hell as much as possible. If needed, try to include all
code toggled by a define in one block.
- Make sure the assembly code is readable after compiling: it should have
liberally comments *in the outputted .asm file*. This allows humans to study
the outputted code and figure out more easily if there's still way to
squueze out instructions from the code.
- Instead of prematurely adding %ifdef toggles to optimize away unused
features, start with the most advanced featureset and see if you can
implement it in a generalized way. For example, all the modulations are
now added into the values when they are converted from integers, in a
implement it in a generalized way. For example, all the modulations are now
added into the values when they are converted from integers, in a
standardized way. This got rid of most of the %ifdefs in 4klang. Also, with
no %ifdefs cluttering the view, many opportunities to shave away
instructions became apparent. Also, by making the most advanced synth
@ -201,34 +258,48 @@ Design philosophy
becomes untolerable.
- Benchmark optimizations. Compression results are sometimes slightly
nonintuitive so alternative implementations should always be benchmarked
e.g. by compiling and linking a real-world song with [Leviathan](https://github.com/armak/Leviathan-2.0)
and observing how the optimizations
affect the byte size.
e.g. by compiling and linking a real-world song with
[Leviathan](https://github.com/armak/Leviathan-2.0) and observing how the
optimizations affect the byte size.
Background and history
----------------------
[4klang](https://github.com/hzdgopher/4klang) development was started in 2007
by Dominik Ries (gopher) and Paul Kraus (pOWL) of Alcatraz. The [write-up](
http://zine.bitfellas.org/article.php?zine=14&id=35) will still be helpful for
anyone looking to understand how 4klang and Sointu use the FPU stack to
manipulate the signals. Since then, 4klang has been used in countless of scene
productions and people use it even today.
[4klang](https://github.com/hzdgopher/4klang) development was started in 2007 by
Dominik Ries (gopher) and Paul Kraus (pOWL) of Alcatraz. The
[write-up](http://zine.bitfellas.org/article.php?zine=14&id=35) will still be
helpful for anyone looking to understand how 4klang and Sointu use the FPU stack
to manipulate the signals. Since then, 4klang has been used in countless of
scene productions and people use it even today.
However, 4klang is pretty deep in the [%ifdef hell](https://www.cqse.eu/en/blog/living-in-the-ifdef-hell/),
and the polyphonism was never implemented in a very well engineered way (you
can have exactly 2 voices per instrument if you enable it). Also, reading
through the code, I spotted several avenues to squeeze away more bytes. These
observations triggered project Sointu. That, and I just wanted to learn x86
assembly, and needed a real-world project to work on.
However, 4klang is not actively developed anymore and the polyphonism was never
implemented in a very well engineered way (you can have exactly 2 voices per
instrument if you enable it). Also, reading through the code, I spotted several
avenues to squeeze away more bytes. These observations triggered project Sointu.
That, and I just wanted to learn x86 assembly, and needed a real-world project
to work on.
What's with the name
--------------------
"Sointu" means a chord, in Finnish; a reference to the polyphonic capabilities
of the synth. Also, I assume we have all learned by now what "klang" means in
German, so I thought it would fun to learn some Finnish for a change. And
[there's](https://www.pouet.net/prod.php?which=53398)
[enough](https://www.pouet.net/prod.php?which=75814)
[klangs](https://www.pouet.net/prod.php?which=85351) already.
Credits
-------
The original 4klang was developed by Dominik Ries ([gopher](https://github.com/hzdgopher/4klang)) and Paul Kraus
(pOWL) of Alcatraz.
The original 4klang was developed by Dominik Ries
([gopher](https://github.com/hzdgopher/4klang)) and Paul Kraus (pOWL) of
Alcatraz. :heart:
Sointu was initiated by Veikko Sariola (pestis/bC!).
Apollo/bC! put the project on the path to Go, and wrote the prototype of the
tracker GUI.
PoroCYon's [4klang fork](https://github.com/PoroCYon/4klang) inspired the macros
to better support cross-platform asm.