DXVU Meter is an ActiveX control (click here for a .NET version of this control), which can monitor any audio device configured as a recording source, such a Microphone, CD ROM, etc... and display the monitored audio levels like a standard VU Meter or as an Oscilloscope.

The VU display mode works by calculating the RMS value of the monitored audio and displaying the peak value in the form of a peak bar.
The Oscilloscope, rendered using DirectX, works by taking samples of the monitored data and displays it as a waveform.

DXVU Meter is also able to save to a WAV file the monitored audio data and since it uses a circular (or infinite) buffer there's no limitation on the amount of audio that can be captured.

The interface of the control is fully resizable in order to let it fit into any form design. The VU mode also supports vertical and horizontal placement of the bars.

DXVU Meter uses the DirectX 8.0 interface, so in order to use the control; the target machine must have the DirectX 8.0 (or above) runtime libraries installed.

These libraries are free and can be obtained from Microsoft at their DirectX web site: http://microsoft.com/directx

The setup for DXVU Meter includes the binary distribution of DXVU Meter, a complete documentation in HTML format and several sample application with their source code in Visual Basic 6 format. Here's the description for some of them:

This powerful real-time spectrum analyzer is a great example of what you can do with DXVU Meter.

The Spectrum Analyzer provides three rendering modes: line, bars and leds. You can customize the colors, set options usually found on professional spectrum analyzers such as logarithmic scales, hold peaks, DTMF detection and more.
Also, the horizontal scale (frequency) is dynamic so you can select a range of frequencies to analyze and even zoom to the range.

The library used to generate and render the Fast Fourier Transform is included with DXVU Meter and it's free so you can use it in all your applications.

In this sample it is demonstrated how to detect silences and peaks to perform different actions.

When the audio is below the set point it will stop recording. When the audio is at the set point, or above it, then the application will start recording.

This new application, included with DXVU Meter version 3.0, combines the above two samples into one. With FVMonitor you set a volume and frequency set point to perform a custom action.

When the audio volume reaches the specified level at the desired frequency an action will be triggered.

• MixerPRO: Used to detect and control the level of the sound card's recording sources.
• xFXSlider: Used instead of Windows' default slider and provide a much more versatile control over the sample application's parameters.