VAC is a "wave-version" of the "MIDI loopback cable" like MultiMid or Hubi's Loopback drivers. It is also similar to "What You Hear" (or "What U Hear") feature of Sound Blaster Live! and Audigy cards.
If more than one applications are sending audio to VAC, it will mix all streams together. If more than one applications are receiving audio from VAC, it will share the same audio data between all targets.
VAC is useful to record application's audio output in real time (for example - Generator, Reality or other software synth), or transfer a sound stream to another application processing it. You can, for example, use two or more software audio generators/synthesizers/sequencers to produce audio streams sending them to VAC Out, and record the mixed stream from VAC In using any recording software - Windows Sound Recorder, Audacity, Sound Forge, WaveLab, Adobe Audition (formerly Cool Edit), Gold Wave, Cakewalk/Sonar, Cubase/Nuendo etc.
With an ASIO wrapper like ASIO4ALL from Michael Tippach, you can use VAC in ASIO supporting applications.
If you use an audio encoder application that encodes a stream coming from a sound card, you can use VAC to supply such encoder with a stream produced by other application.
You can use VAC to capture an output sound stream from the application that doesn't allow to write it into WAV file directly. Unlike Total Recorder allowing you to simply save audio stream, VAC allows to route it in real time.
If you are using some Voice Over IP (VoIP) and/or Internet Telephony applications like Skype, you can use VAC to record your calls and conversations.
VAC needs no audio card; it is a "virtual audio card" itself.
A detailed description is included into a free trial package.
Since VAC 4 is a WDM driver, there are some benefits but some (generally older) applications that use MME (waveIn/waveOut) interface can work better with the older VAC 3 version. This version also supports Windows 98/ME.
If you need to simply share your In/Out wave ports among several applications, take a look to the Wave Clone software.
Features
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How to install
Release history
Support
Source code and other options
Use VAC with UniScope!
Other software from me
Features
Windows 2000/XP/2003/Vista platforms (32-bit and 64-bit)
Local session only (not available from Remote Desktop).
Native WDM/KS audio technology.
Up 256 Virtual Cables (Windows limits number of MME devices to 32. Number of DirectSound devices is not limited). Trial version is limited to 2 cables only.
1..20 milliseconds per interrupt.
1..100 pin instances.
Almost any of fixed point PCM audio formats (200..1000000 samples per second, 8..32 bits per sample, 1..8 channels). Floating point formats are not supported.
Almost no sound latency with maximal interrupt frequency.
Unlimited number of clients connected to each port.
Signal mixing (with saturation) between output port clients.
PCM format conversion.
Volume control features.
Control Panel application to dynamically configure cables.
Audio Repeater application that transfers from any Wave In to any Wave Out port.
http://rapidshare.com/files/208208674/Virtual.Audio.Cable.v4.09_by_Azi.rar
