VST MIDI Driver (Falcomod)

is a Windows user-mode software MIDI synthesizer driver which is capable of using any 32 or 64 bit VST2 Instruments.

This fork of the driver supports Windows NT4 SP6/2000/XP/Vista/7/8/10/11 (both WaveOut and ASIO output).


The source code can be downloaded from Github:

The change log and new releases can also be found on GitHub:

The source code of the included ASIO2WASAPI plugin can also be downloaded from GitHub:


If you would like to support the development of VST MIDI Driver (Falcomod) you can donate through PayPal.


New features and fixes of this fork:

Some guidelines for the new features and options :

  1. Sample rate: The best option is if you select the sample rate to be the same as the audio card's sample rate selected on Windows -> Speaker Properties -> Advanced tab. This way no resampling is necessary by Windows. The only problem is that some plugins are sample rate dependent or work best with a particular sample rate. E.g. S-YXG50 works best only with 44100/48000 Hz. On other frequencies it produces bad output (most noticeable at 32000 and 192000 Hz , but 96000 Hz is alo problematic). Munt VSTi has the most proper timing on 32000 Hz. OPL3 plugins have the best emulation accuracy at 49716 Hz. Of course in these cases the emulation accuracy is more important than some resampling. Generally 48000 Hz is the most compatible one.

  2. Buffer size: Lower size means lower latency but the sound output is more fragile (intermittent pauses because of high CPU consumption etc.). So it is always a compromise. For a general Midi usage scenario (where real-time jamming is not the most important) I recommend values in the 80-160 ms range for waveOut mode. Too high latency can result in disturbing delay between visual effects (such as virtual piano, Midi channel volume displays etc.) and audible audio.
    For ASIO output mode (so real-time jamming) the recommended way is to set as low value as possible in the 10-40ms range or leave it at Default and set the buffer size at the ASIO control panel of the ASIO driver.

  3. Sample format: The default is 32-bit float but 16-bit int can also be selected. On older Windows versions 16-bit int can be more compatible but even on modern Windows versions (Vista+) 16-bit int option can be somewhat still relevant. It's because in case of 32-bit float output modern Windows versions apply a limiter/compressor automatically which on the one hand prevents clipping but on the other hand can result in wavy volume response and makes it harder to calibrate proper synth output level.

  4. Output Gain: This increases/decreases the output level after the plugin has already rendered the sound so it cannot prevent clipping in the synth's digital domain. For plugins that include volume/gain slider on the VST editor interface (such as S-YXG50) it may be more useful to use the editor's volume/gain control in real-time. But e.g. in case of SC-VA where the sound output level is rather low even at maximum this feature can be useful.
    It can be also useful for editorless plugins.

  5. Show VST dialog when port is activated: If it is selected then the VST editor is shown when a port is opened by a MIDI client. In case of more complex plugins it can be hard to tune settings on the configuration dialog without hearing the results. If the VST editor is shown then you can fine tune and save the settings while the plugin is producing audio.
    Be aware that it is possible that you cannot save plugin settings from the editor at runtime while you can from the configuration dialog.
    It's because the configuration dialog runs with elevated administrator rights while the driver does not. So make sure to give write permission for normal 'Users' to the plugin's folder (this usually has to be done for plugins located in Program Files (x86) or Program Files).

  6. 4 channel mode: If this option is selected then you can enjoy surround Midi sound. In WaveOut mode Port A is assigned to Front speakers and Port B is assigned to Rear speakers. In ASIO mode the speaker assignment is somewhat more versatile since you can select any ASIO channel pairs (left/right) to port A and you can set the offset from port A for the channel pair of port B.
    You can use FSMP or Midi Trail to play back 32-channel Midi files where Midi channels 1-16 can be played on port A and Midi channels 17-32 on port B.
    Besides 32-channel Midi playback you can also use 4 channel audio option for gaming. E.g. if you assign DosBox Midi to port B then game music would sound from rear speakers while normal game audio/digital effects from front speakers.

  7. Always on Top: By default both the configuration dialog and VST editors open in topmost state to prevent z-order problems at startup (e.g. the editors may open up behind the MIDI client that opened the port). But in some cases some VST editor related dialogs and ASIO control panels may open up behind the dialog that is in topmost state. In these cases disabling topmost status can be helpful. So if always on top is disturbing for some reason then you can switch it off for both the configuration dialog and VST editor dialogs.

  8. System tray menu: Even if you do not select the 'Show VST dialog when port is activated' option you can still open (and close) VST editor dialogs with the help of the system tray menu. From this menu you can also send GM/GS/XG/GM2 SysEx reset messages to active VSTi plugin instances. This way you can set your preferred Midi mode or simply reset the plugin to corresponding defaults even if the used Midi client has no such feature.
    From version 2.2. you can also switch between pre-configured plugins from the tray menu.

Storage of settings:

The driver settings are stored in the registry at HKEY_CURRENT_USER\Software\VSTi Driver. The plugin settings are stored in the plugin's folder with the same name as the plugin dll but with the extension of .set.

Some rare to be changed driver settings have no options available on the GUI but can be changed directly from the registry if necessary:

1. EnableSinglePort32ChMode. Enabled by default so has a value of 1. When the driver used together with FSMP it can accept the special 0xF5 xx MIDI port select messages sent by FSMP to select ports automatically. This way the driver can open port B automatically (or vice versa port A when port B is selected as output port) when a 32-channel MIDI file is detected by FSMP. You can disable this function if you set the value to 0.

2. HighDpiMode. This option sets the High DPI mode of the VST editor dialog together with the embedded GUI of the plugin.
Since VST2 editors mostly do not handle high DPI at all the default is not DPI aware + GDI scaling in Win10 1809+. The default DPI mode is rather compatible but DPI mode can be changed the following way:

HighDpiMode: -5 (0xFFFFFFFB) = Windows enhanced GDI scaling (Win10 1809+). This is the default.
HighDpiMode: -1 (0xFFFFFFFF) = Windows normal scaling. This is the most compatible one but results in blurry texts. This is the default before Win10 1809 (Vista/7/8/10).
HighDpiMode: -2 (0xFFFFFFFE) = Plugin scaling. This is the less compatible option. Since VST2 editors cannot do scaling in 90% of cases this option most likely results in tiny editors.
Enhanced GDI scaling optimizations are mostly visible on fonts/texts and common controls (they are sharper). Unfortunately bitmaps cannot be scaled without blur.


Brief history of the driver:

The original driver was written by Mudlord and Kode54. Unfortunately development has stopped at about 2017.
According to Kode54 even the source code had been lost.
When Windows 10 version 2004 had been released the driver stopped working in the sense that it could not survive reboots.

Later it seems the source code had been found and a new fork from Arakula fixed the reboot related problems on Windows 10.
Another fork from DB50XG was also born.
Unfortunately both forks have been abandoned since then and both forks were left in a problematic state with major bugs.

Arakula's fork had 2 major problems:
It could not save/load plugin settings (actually this problem was inherited from the original driver).
It had huge 500 ms latency thanks to some Bass related misconfiguration and a path related bug that prevented basswasapi.dll to be found.

DB50XG's version cured the save/load related problem but it had non-working Bass/BassWASAPI code paths so only ASIO output worked.
And even the ASIO output mode had serious stability problems (quitting from the Midi client in 99% of cases resulted in a hung ghost process).
This fork also had broken dual port functionality (only port A worked).

And both forks inherited the problem of integrated Bass libraries. Kode54 had decided to replace pure WinMM Waveout to Bass/Basswasapi right before the abandonment. Since VST Midi driver is an in-process driver it could not use its own Bass libraries if the Midi client already used some other versions of Bass libraries.
More info: Re: Yamaha S-YXG50 Portable VSTi (a software MIDI synth)

This was also true the other way around: If a Midi client used VST Midi driver then it could not use its own Bass libraries afterward since the libraries were already loaded to the client's address space through VST Midi driver.
More Info: Re: Falcosoft Soundfont Midi Player + Munt VSTi + BassMidi VSTi

Both situations could cause subtle and hard to debug problems.

The change to Bass libraries also resulted in inferior MIDI timing/precision. The ASIO output mode of DB50XG's fork had the same problem.
Both versions dropped timestamps so Midi precision depended on Bass update period (5-10ms at best case) or ASIO buffer size (above about 20ms buffer size the result was horrible).

On Vogons there was (actually still is) a thread about the driver where many would have liked to see a version that fixed the main bugs.
That was the point where the story of this fork began:


VST MIDI Driver (Falcomod) in action:

FSMP + VST Midi driver - 32 channel KONAMI Midi files FSMP + VST Midi driver - 32 channel KONAMI Midi files

Have fun.

Zoltán Bacskó (Falco)


Ps: One of the best free all around VST2 instrument plugins is S-YXG50.
It's a very good replacement for the Windows default MS GS Soft Synth and it works perfectly with this driver:


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