Audio Recording


System Setting


This application records system-wide audio output into movie file.
It includes audio played by other applications and MIDI sequence converted into audio.
For example, our DoctorMX and SynVisum has a function that executes scenes synchronized to music player (iTunes, Windows Media Player).
By recording system-wide audio output, audio played by music player is also recorded into a movie file.
Also, SynVisum can play multiple movie or audio files simultaneously, thus actual mixed output can be recorded with minimal additional process.

It is called as "loopback" to return output back to input.

Default audio output device
System provides a function to specify default audio output device.
(by means of Control Panel, or System Preferences)
It is used as output device for audio played by applications.
This application records audio loopback-ed from default audio output device.
Specialized audio applications may offer setting to specify audio output device explicitly.
If it uses output other than default, such audio is not recorded.

Audio Compression
"PCM" (Linear PCM) does not compress nor degrade audio.
However, file becomes larger.
On Windows version, recorded into AVI format file.
In this case, Windows Media compressions (WMAudio, etc.) are not appropriate.
Use other compression instead.
(MPEG Layer-3, IMA ADPCM, etc.)

To use a loopback function, some system side settings are required.
Per system settings are explained below.

Windows Vista and later

No setting is required, because system itself provides loopback function.
(independent of audio device specification)

Windows XP

In Control Panel, specify default audio input device.
This input device is used for recording.

Loopback function is provided by audio device.
In "Volume Control", set "Recording" volume.
In the example below, "Stereo Mix" is loopback.
(name for loopback differs depending on device.
"Waveout Mix", "Mix Out", "What You Hear", etc.)

There may be device that does not offer loopback function.
For such device, loopback can be achieved by connecting output to input using external cable.
If necessary, use a splitter cable to connect to speaker too.


Because system does not provide loopback function, install "kuwatec Audio Loopback" we provide instead.
Download kuwatec Audio Loopback installer
v1.0.5 (64bit Intel / Apple silicon)

No additional procedure is required for normal use.
Recording mechanism using "kuwatec Audio Loopback" is explained below.
Read if necessary.

Details of kuwatec Audio Loopback
"kuwatec Audio Loopback" operates as a virtual audio device.
It returns output audio back to input.

If "kuwatec Audio Loopback" is installed, this application uses it as audio input.
(otherwise, use default audio input device)
Because "kuwatec Audio Loopback" does not have actual audio output, this application outputs loopback-ed audio to "original" default output device.

When [Movie Setting] - [Record with Audio] is selected, "kuwatec Audio Loopback" becomes default audio output device.
This makes audio played by applications are output to "kuwatec Audio Loopback".
In addition, the "original" default audio output device is used as output for loopback-ed audio.

In this state, system provided volume (a slider accessible from a menu bar) controls output of "kuwatec Audio Loopback".
Thus, it also works as recording volume.
(If necessary, volumes of other portions, such as "original" default output, can be controlled with "Audio MIDI Setup" application in the "Utilities" folder)

When [Movie Setting] - [Record with Audio] is deselected, "original" default audio output device is recovered.

Additional information:
"kuwatec Audio Loopback" is installed on the startup volume, into:
  • OS X 10.8 or earlier:
    /System/Library/Extensions folder
  • OS X 10.9 or later:
    /Library/Extensions folder
as "kuwatecAudioLoopback.kext".
You can delete it if unnecessary.
Administrator password is required on installation and deletion.

"kuwatec Audio Loopback" does not affect other process, unless used as an audio device explicitly.

"kuwatec Audio Loopback" does not degrade passing audio quality, but latency will increase for several 10mS.

Mac OSX 10.7 and later

The method explained above in "Mac OSX" can be used.
As an alternative, utilizing "Multi-Output Device" function provided by system, same audio can be output to both normal device and "kuwatec Audio Loopback" simultaneously.
To setup "Multi-Output Device", use "Audio MIDI Setup" application in "Utilities" folder.

Include "kuwatec Audio Loopback" in a "Multi-Output Device", and make it as a default output device.

If a default output device contains "kuwatec Audio Loopback", this application does not change a default output device.
("kuwatec Audio Loopback" is used as record input)

In this state, system provided volume (a slider accessible from a menu bar) cannot be used at all.
Each volume can be controlled with "Audio MIDI Setup" application.