If you have a signal-processing algorithm that you would like to apply system-wide on a Windows tablet or PC as part of a signed audio driver package,, then the Optimal Sound APO Framework is a perfect fit.

The licensing is normally combined with a development effort which results in a fully implemented driver package based on the Windows† HD Audio or USB class driver, as well as components which can be easily and quickly integrated into a third party driver package from any of the loading hardware vendors.

We typically develop each new project on the HD Audio or USB Audio class drivers, which allows the APO development effort to be fully decoupled from integration with IHV drivers. This allows the Optimal-built components to be fully tested in isolation, and provides an easy way to compare performance between IHV and class drivers. This makes integration with IHV drivers very simple and straightforward.


The APO Framework supports

  • The new and largely undocumented APO types required for Windows 8.1: SFX (Stream Effects), MFX (Mode Effects), and EFX (Endpoint Effects)
  • The older LFX (Local Effects) and GFX (Global Effects) APO types required for Windows 8, Windows 7, and Windows Vista
  • Hardware Proxy APOs, used with offloaded processing
  • Windows 8.1, Windows 8, Windows 7, and Windows Vista
  • Both 64-bit and 32-bit versions of Windows
  • Integration with all major HD Audio Codec vendors
  • Integration with all major HDMI  Codec vendors
  • HD Audio and USB Audio class drivers can be used, no custom hardware or driver needed in order to install APO at system level
  • USB Headsets (wired and wireless)
  • Microphone Arrays, up to 4 microphones.
  • 2.0, 2.1, 4.0, 5.1, and 7.1 speaker configurations
  • 7.1->2, 5.1->2, and 2.0 audio virtualizers for both headphones and speakers
  • Spreader/phase-decoder upmixing for 2->5.1, 2->7.1, and 5.1->7.1
  • Proprietary-format encoders like Dolby Digital Live† and DTS Interactive†
  • Customized public or private APIs for real-time control of APOs from modern (metro) apps, desktop apps, audio control panel
  • Both Capture and Render
  • Protection against floating point underflows and denormals on 32-bit systems. Without this protection, algorithms that have values that decay to zero could generate interrupt storms that seriously degrade system performance.
  • Support for Echo Canceller reference signal for Capture APOs
  • Support for Lync† & Skype†
  • Support for ARM† Windows RT tablets
  • Independent capture processing for Speech Recognition and Communications streams
  • I2S and Hardware-offloaded systems
  • We normally do not need to see your proprietary signal-processing source code. Instead we provide you with a shell DLL that you use to implement your code. We also provide you with a command-line test app that can fully exercise and debug the shell DLL outside the APO real-time environment.
  • The debug variant of the APO has the ability to write incoming and outgoing streams to a file, to more easily pinpoint the cause of signal processing issues involving the APO.
  • All of our APOs implement Event Tracing for Windows for easy integration and analysis with Windows Performance Analyzer, Perfview, and Windows Performance Recorder. This makes it quick and easy to trace performance issues down to the source code level.

Audio Property Page

The only officially supported mechanism for branding and to control APO parameter settings in real-time is to use an Audio Property page, which is installed on the associated audio endpoint within the desktop Sound Control Panal.

The associated APO control parameters are stored in the Windows registry on either a global basis (applies to all endpoints) or on a per-endpoint basis. The global approach is usually used when applications other than an Audio Property Page need to be able to control an APO.

Most OEMs require the Audio Property page to be localized for at least 40 languages. While Optimal doesn't provide translation and validation services, we can handle all other aspects of localization