Convolver 4.3 released on http://convolver.sf.net

Convolver is an open source high performance Windows application for applying long finite impulse response (FIR) filters to multi-channel digital audio in the form of

* a real time DSP audio plug-in (DMO) for Windows Media Player. The install package also contains

* two DirectX/DirectShow filter versions — ConvolverWrapper or the equivalent ConvolverFilter — for Adobe Audition and real time applications such as Zoom Player Pro, TheaterTek 2.2, Windows Media Player Classic, J.River Media Center (when used with the DirectX host plug-in), or Console. See the setup walkthrough for ZoomPlayer after reading this page for further details. In many cases the DMO (Convolver DSP plug-in will also work).

* a VST plug-in and finally, there are a number of

* command line applications for testing performance, and convolving files offline, for example

Convolver will take a set of impulse response (FIR filter) files and convolve them with sound paths mixed from the input channels, mixing the results into a set of specified output channels.

Applications:

Why would you want to do this? There are several main applications:

* With a suitable impulse response generated by a tool such as DRC you will be able to play sound corrected for your room response. For more details, see Ed Wildgoose's Duff Room Correction site.

* You can also use Convolver for bass management, cross-overs, cross-talk cancellation, equalization and other purposes that require the source signal to be filtered and redirected to different output channels.

* You can also use Convolver as an effects filter (reverb) in Adobe Audition, or other sound or music application that accepts DX filters.

Features:

* Performance is excellent, possibly the best available under Windows, and subject continual improvement. A stereo 65536-tap filter, the largest that makes sense when applied to a 44.1kHz source, executes at 40 times real time, representing a 3% cpu hit, on a 3.4GHz Pentium 4. Even on a 300MHz Pentium II, the reported cpu hit is about 30% when convolving with such a filter. So your old machine can be put to good use. Mixing channels results in some slowdown (six 65536-tap filters will consume less than 10% cpu on a 3.4GHz Pentium 4).

* Arbitrary-length convolutions for unusual applications (1 million tap limit imposed only as a sanity check)

* Multi-channel input and output, 8, 16, 20, 24 and 32-bit PCM and 32 and 64-bit IEEE Float

* Mixing, scaling and delay of both input and output channels (eg, for "true stereo" convolution, or cross-talk cancellation)

* Dither and noise shape of 8, 16, 20 and 24-bit output

* Wide range of filter file formats accepted (Microsoft WAV, SGI/Apple AIFF/AIFC, Sun AU/Snd, Raw (headerless 32-bit IEEE float), Paris Audio File (PAF) Commodore IFF/SVX, Sphere/NIST WAV, IRCAM SF, Creative VOC, SoundForge W64, GNU Octave MAT4/5, Portable Voice Format, Fasttracker 2 XI, HMM Tool Kit HTK)
* Sample encodings supported include unsigned and signed 8, 16, 24 and 32 bit PCM, IEEE 32 and 64 floating point, U-LAW, A-LAW, IMA ADPCM, MS ADPCM, GSM 6.10, G721/723 ADPCM, 12/16/24 bit DWVWk, OK Dialogic ADPCM, and 8/16 DPCM. Wavpack files are not currently supported.

* Windows Media Player plug-in (DMO) and DirectShow / DirectX / DX filter and VST interfaces.

Several filters can be loaded at once. The first to match the playback format (channels, sample rate) is automatically selected.

In this release:

Used FFTW 3.1.2 (which is faster and should run on more non-Pentium 4 platforms)

Disabled "Lost filter" convolverVST error message, to give the user a chance to select a filter

Feedback welcome