Home News Download Usage Command line utilities Feedback Troubleshooting Links


Config file
ZoomPlayer Pro
Panned binaural demonstration

Web This site


To install Convolver:

1. download convolver and unzip it.

There are two versions: a complete source version (convolver-source), and a version that contains only the installation package (convolver).

  • The source version can be run from Visual Studio 2005, or
  • Run Setup.exe to install the installation package version.

Getting started

The following describes getting started with WMP, Media Player Classic and Adobe Audition.  There is also a full walkthrough for ZoomPlayer Pro which is more complex to set up. Other DirectShow hosts, such as Media Player Classic, may offer a choice of using Convolver DSP plug-in (ConvolverWMP, a DMO), ConvolverFilter or ConvolverWrapper.  These have identical functionality.

Windows Media Player

2.  In Windows Media Player select Tools | Plug-ins | Options.

On the Plug-ins tab, select Audio DSP you should see this:

Media Player Classic

2. In Media Player Classic hit O | External Filters | Add Filter ... | ConvolverFilter | OK and then set the merit to Prefer:


Adobe Audition

2. Select Effects | Refresh Effects List and confirm that you want to refresh the effects list.

3. Select Properties to configure the plug-in:

The number of taps will be double the length of the relevant filter file.

3. Double click on ConvolverFilter

3. The properties page may come up when you scan for DirectX filters, or select Effects | DirectX | ConvolverFilter (or ConvolverWrapper) to configure the plug-in

4. Select Get config or IR and pick up either

an impulse response (IR) sound file
which will be a WAV (or other supported sound file format) file.  The file will be convolved channel by channel with the source.  The file must have the same number of input and output channels and sample rate as the source that you are playing back and the number of speakers that you are using. Raw PCM (.PCM) files are assumed to be single-channel 44.1kHz 32-bit float files.  Similarly .DBL files are assumed to be single-channel 44.1kHz 64-bit float files.  If you need to specify a different sample rate with a raw file, use a config file.
This is not the best approach theoretically for room correction, but is simple and may give you good sound anyway; or
a configuration (text) file
This is more complex, but more flexible approach.  There are also some examples, although they will not be intelligible without looking at the config file instructions first.
The links page has some pointers to sources of impulse responses that you can try, just to get going. See duffroomcorrection if you want to record your own room impulse responses.

5. The input channels are also scaled by 10 Attenuation / 20. So negative values will help to to prevent clipping and positive ones will result in amplification.  If you hear no playback, try raising this value.

  •  Push the Calculate optimum attenuation button to have the plug-in calculate a (probably conservative) attenuation value.  The optimum attenuation will vary slightly from calculation to calculation.  Subsequent calculations will typically execute faster than the first calculation as Convolver tunes itself to your system.
  • The theoretical maximum gain for the filter that you have selected is shown as the peak gain in the filter description (70dB in the above example). You could set the attenuation to the negative of this value (eg, -70dB in the above example) although that value is likely to be extremely conservative and you will probably just hear silence. The Estimated gain is less conservative.
  • Set Attenuation to 0 for no attenuation.
  • Attenuation must be between ±1000.

6. The dither and noise shaping settings apply only to 8, 16, 20 and 24-bit PCM output and have no effect otherwise. Triangular uses triangular "high pass" additive dither and is the theoretically optimal setting.  The perceived noise due to dither can be reduced by using noise shaping.

7. The No of partitions setting allows you to tune the convolution algorithm to your cpu (and the size of its cache).  Try values such as 0, 2, 4, 8 or 16.  Observe how long it takes to Calculate optimum attenuation to find the best number of partitions for your setup or, preferably, use the perftest command line utility.. A value of 0 will use straight overlap-save convolution. (A setting of 1 will effectively do the same, or more precisely overlap-add, but slightly less efficiently.)  Also, the larger the number of partitions, the shorter the lag between input and output.

8. Convolver tunes itself for a particular filter and number of partitions when the filter is loaded or the number of partitions changed.  The Tuning rigour setting allows you to specify how much effort the convolution routines put into tuning themselves to your system:

specifies that, instead of actual measurements of different algorithms, a simple heuristic is used to pick a (probably sub-optimal) method quickly.
finds an optimized method by actually and measuring the execution time of candidate methods, so there may be a pause while this happens. Depending on your machine, this can take some time (often a few seconds). This is a good default option.
is like Measure, but considers a wider range of algorithms and often produces a “more optimal” method (especially for large convolutions), but at the expense of much longer tuning time (minutes). This option also considers multi-threaded execution, which may be a benefit for longer filters and multiple processors (or even multi-core and perhaps even hyperthreading processors).
is like Patient, but considers an even wider range of algorithms, including many that are unlikely to be fast, to produce the most optimal calculation method but with a substantially increased tuning time.
Take 1 minute
Finds the best method that it can within a minute for each filter path.

The tuning results are retained for reuse in a file called wisdom.fftw.

9. After loading a new (or initial) filter, you may need to restart Windows Media Player (or select a new track) to get WMP to recognise Convolver's new capabilities.

10. In the case of Media Player Classic, you should be able to see the playback format of the input and output. After selecting a file for playback (Ctrl-O), select Play | Filter | ConvolverFilter | Pin Info.


Home ] News ] Download ] [ Usage ] Command line utilities ] Feedback ] Troubleshooting ] Links ]

Send mail to with questions or comments Convolver or about this web site.
Copyright © 2006-8 Convolver
Last modified: 16-Jan-2008 20:24 -0000 Logo