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https://github.com/dechamps/flexasio

A flexible universal ASIO driver that uses the PortAudio sound I/O library. Supports WASAPI (shared and exclusive), KS, DirectSound and MME.
https://github.com/dechamps/flexasio

asio asio-drivers audio audio-plugin c-plus-plus directsound mme portaudio wasapi windows

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A flexible universal ASIO driver that uses the PortAudio sound I/O library. Supports WASAPI (shared and exclusive), KS, DirectSound and MME.

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README 

        
# FlexASIO, the flexible universal ASIO driver

*Brought to you by [Etienne Dechamps][] - [GitHub][]*



*ASIO is a trademark and software of Steinberg Media Technologies GmbH*



**If you are looking for an installer, see the

[GitHub releases page][releases].**



## Description



FlexASIO is a *universal [ASIO][] driver*, meaning that it is not tied to

specific audio hardware. Other examples of universal ASIO drivers include

[ASIO4ALL][], [ASIO2KS][], [ASIO2WASAPI][]. [KoordASIO][] is a derivative of

FlexASIO that focuses on WASAPI and user convenience.



Universal ASIO drivers use hardware-agnostic audio interfaces provided by the

operating system to produce and consume sound. The typical use case for such a

driver is to make ASIO usable with audio hardware that doesn't come with its own

ASIO drivers, or where the bundled ASIO drivers don't provide the desired

functionality.



While ASIO4ALL and ASIO2KS use a low-level Windows audio API known as

*[Kernel Streaming]* (also called "DirectKS", "WDM-KS") to operate, and

ASIO2WASAPI uses [WASAPI][] (in exclusive mode only), FlexASIO differentiates

itself by using an intermediate library called [PortAudio][] that itself

supports a large number of operating system sound APIs, which includes Kernel

Streaming and WASAPI (in shared *and* exclusive mode), but also the more mundane

APIs [MME][] and [DirectSound][]. Thus FlexASIO can be used to interface with

*any* sound API available on a Windows system. For more information, see the

[backends documentation][BACKENDS].



Among other things, this makes it possible to emulate a typical Windows

application that opens an audio device in *shared mode*. This means other

applications can use the same audio devices at the same time, with the

Windows audio engine mixing the various audio streams. Other universal ASIO

drivers do not offer this functionality as they always open audio devices in

*exclusive mode*.



## Requirements



 - Windows Vista or later

 - Compatible with 32-bit and 64-bit ASIO Host Applications



## Usage



After running the [installer][releases], FlexASIO should appear in the ASIO

driver list of any ASIO Host Application (e.g. Cubase, Sound Forge, Room EQ

Wizard).



The default settings are as follows:



 - DirectSound [backend][BACKENDS]

 - Uses the Windows default recording and playback audio devices

 - 32-bit float sample type

 - 20 ms "preferred" buffer size



All of the above can be customized using a [configuration file][CONFIGURATION].

You might want to use a third-party tool such as flipswitchingmonkey's

[FlexASIO GUI][FlexASIO_GUI] to make this easier.



For more advanced use cases, such as low-latency operation and bit-perfect

streaming, see the [FAQ][].



## Troubleshooting



The [FAQ][] provides information on how to deal with common issues. Otherwise,

FlexASIO provides a number of troubleshooting tools described below.



### Logging



FlexASIO includes a logging system that describes everything that is

happening within the driver in an excruciating amount of detail. It is

especially useful for troubleshooting driver initialization failures and

other issues. It can also be used for verification (e.g. to double-check

that FlexASIO is using the device and audio format that you expect).



To enable logging, simply create an empty file (e.g. with Notepad) named

`FlexASIO.log` directly under your user directory (e.g.

`C:\Users\Your Name Here\FlexASIO.log`). Then restart your ASIO Host

Application. FlexASIO will notice the presence of the file and start

logging to it.



Note that the contents of the log file are intended for consumption by

developers. That said, grave errors should stick out in an obvious way

(especially if you look towards the end of the log). If you are having

trouble interpreting the contents of the log, feel free to

[ask for help][report].



*Do not forget to remove the logfile once you're done with it* (or move

it elsewhere). Indeed, logging slows down FlexASIO, which can lead to

discontinuities (audio glitches). The logfile can also grow to a very

large size over time. To prevent accidental disk space exhaustion, FlexASIO will

stop logging if the logfile exceeds 1 GB.



### Device list program



FlexASIO includes a program that can be used to get the list of all the audio

devices that PortAudio (and therefore FlexASIO) knows about, as well as detailed

information about each device.



The program is called `PortAudioDevices.exe` and can be found in the `x64`

(64-bit) or `x86` (32-bit) subfolder in the FlexASIO installation

folder. It is a console program that should be run from the command line. It

doesn't matter much which one you use.



### Test program



FlexASIO includes a rudimentary self-test program that can help diagnose

issues in some cases. It attempts to emulate what a basic ASIO host

application would do in a controlled, easily reproducible environment.



The program is called `FlexASIOTest.exe` and can be found in the `x64`

(64-bit) or `x86` (32-bit) subfolder in the FlexASIO installation

folder. It is a console program that should be run from the command

line.



It is a good idea to have [logging][] enabled while running the test.



Note that a successful test run does not necessarily mean FlexASIO is

not at fault. Indeed it might be that the ASIO host application that

you're using is triggering a pathological case in FlexASIO. If you

suspect that's the case, please feel free to [ask for help][report].



## Reporting issues, feedback, feature requests



FlexASIO welcomes feedback. Feel free to [file an issue][] in the

[GitHub issue tracker][], if there isn't one already.



When asking for help, it is strongly recommended to [produce a log][logging]

while the problem is occurring, and attach it to your report. The output of

[`FlexASIOTest`][test], along with its log output, might also help.



---



![ASIO logo](ASIO.jpg)



[ASIO]: http://en.wikipedia.org/wiki/Audio_Stream_Input/Output

[ASIO2KS]: http://www.asio2ks.de/

[ASIO2WASAPI]: https://github.com/levmin/ASIO2WASAPI

[ASIO4ALL]: http://www.asio4all.org/

[BACKENDS]: BACKENDS.md

[CONFIGURATION]: CONFIGURATION.md

[DirectSound]: https://en.wikipedia.org/wiki/DirectSound

[Etienne Dechamps]: mailto:[email protected]

[FAQ]: FAQ.md

[FlexASIO_GUI]: https://github.com/flipswitchingmonkey/FlexASIO_GUI

[file an issue]: https://github.com/dechamps/FlexASIO/issues/new

[GitHub]: https://github.com/dechamps/FlexASIO

[GitHub issue tracker]: https://github.com/dechamps/FlexASIO/issues

[logging]: #logging

[MME]: https://en.wikipedia.org/wiki/Windows_legacy_audio_components#Multimedia_Extensions_(MME)

[Kernel Streaming]: https://en.wikipedia.org/wiki/Windows_legacy_audio_components#Kernel_Streaming

[KoordASIO]: https://github.com/koord-live/KoordASIO

[PortAudio]: http://www.portaudio.com/

[releases]: https://github.com/dechamps/FlexASIO/releases

[report]: #reporting-issues-feedback-feature-requests

[test]: #test-program

[WASAPI]: https://docs.microsoft.com/en-us/windows/desktop/coreaudio/wasapi