DXVU Meter is an ActiveX control, that
can monitor any audio device configured as a recording source, such as a
Microphone, the 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 display the peak value in the form of a peak bar.
The Oscilloscope works by taking samples of the monitored data and
display it as a waveform.
DXVU Meter is also capable of saving the monitored audio to a WAV file
and since it uses a circular (or infinite) buffer there's no limitation
on the amount of audio that can be captured or saved.
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 runtime libraries installed.
These libraries are free and can be obtained from Microsoft at their
DirectX web site: http://microsoft.com/directx
To test the control, first, you should
have some audio device playing, such as the CD-ROM playing and selected
as the recording source.
To select a recording source open the Windows Mixer, select
Options->Properties, choose the Recording round check and click OK.
Now make sure the CD-ROM line has a checkbox in the "Select"
option and the Volume is high enough.
Now, simply run one of the Tester applications and click on the "StartVU"
Bugs & DEMO Limitations
When placing the control in a form for
the first time, all the leds will appear green. Their color will be
restored when running the application or by changing any of the leds
color. This issue is currently being investigated.
Under Windows 9x/Me, shutting down
the control (by issuing the StopVU method) will take from 3 to 7
seconds. Under Windows 2000 and XP the control takes less than 1 seconds to
perform the exact same operation.
A nag screen will be displayed every
time the control is initialized.
If you wish to write us with your
opinions, suggestions or bug reports about this release of DXVU Meter,
please use our online support form at:
You may also want to visit a public
forum, dedicated to DXVU Meter at:
The control will be made available in
both, the binary version and the control's full source code.
Including Documentation and three tester
applications with their source code
To buy this control online, please
follow this link:
- The rendering engine to display the
Oscilloscope mode (wave form) now uses the DirectX API instead of
the GDI producing a much more fluid wave form while requiring fewer
- The code has been optimized so
multiple controls can be used simultaneously on the same
This optimization should also provide a small performance boost.
- Fixed bug that caused the control
to invert the left and right channels.
- Added support to playback any type
of media file.
The media files that can be played with DXVU Meter will depend on
the filters available on the host machine. This means that if the
host machine has a filter to decode MP3 files, then DXVU Meter will
be able to playback MP3 files.
- Added two new properties:
- Added one new method:
- Added two new samples with source
- Highly improved performance and
memory utilization now allows the control to run with fewer CPU
- Added support for five new events:
Calibration property now
affects the oscilloscope mode.
- Slightly improved quality of the
rendering engine while in oscilloscope mode to properly reflect
clipping and to avoid flickering.
- Highly improved playing quality.
The control will not properly stream wav files and play them without
introducing any noise. It will also stop the playback more
- Added support to play files in
- Add two new sample applications:
- Get DirectX 8 Capabilities: This
application will use the DirectX 8 API to retrieve the supported
playing and recording formats for all the installed sound cards.
- Sample Recorder: One of the most
requested samples is an application that can detect the audio level
on some of the input lines and record or stop recording based on a
pre-set set point.
This application monitors a specific input line and starts recording
when the audio level goes above the set point.
When a silence is detected the application will wait a pre-defined
delay and then stop recording if the duration of the silence extends
the pre-set delay.
- Fixed bug that caused the led
display to render the monitored and played audio incorrectly when a
16bit/Mono mode was selected.
- Fixed bug that caused the
Resolution property to be improperly initialized when the control
Added a new property to set the
background color of the control while in the Leds mode.
- Improved the led display.
- Documented the
Calibration property on the
- Added the return data type
information to all the properties
on the documentation.
now returns a Long as recommended by Microsoft's DirectX
- Added a
new property to set the number of leds to be displayed while the
control is used in VU mode.
- Added support for selecting the
output device for Playback. (See the
- The VU mode now calculates an
average between the last three values monitored to create a smoother
- The control has been re-calibrated
providing more realistic results in the rendering engine. This has
also affected the way the array returned by the
PeakValues event should be
The control should now display 99% exact results regardless of the
sampling frequency being used, of course, as long as the sampling
frequency is at least twice the central frequency of the sampled
data. Because of this, you may notice that the rendering engine
tends to display the same sampled audio at lower levels when using
lower sampling frequencies; this is just a result of the information
being lost at the sampling process.
- Fixed bug that caused the control to
improperly monitor stereo sound under some frequencies.
- All the sample applications have
been re-adjusted to accommodate to the new Calibration system used
by the control.
- The DXVUMeterTester application has
been updated to reflect the new ability of the control to select the
- The Frequency Analyzer 2.0 has been
updated (it's still considered in beta state) and now includes a small document
explaining all the features.
Version 1.x update log