This is a Foobar2000 DSP plug-in that provides a 31 band 1/3 ISO octave equalizer and DRC convolver using code ported from the linux program BruteFIR. While there are many other equalizer plug-ins available, I have found that convolution provides the cleanest equalization from a sonic standpoint.
Since the convolver filter requires a sampling rate that matches the input signal, using it as an equalizer typically presents some difficulty if streams with different sampling rates need to be processed. This plug-in automatically renders filter coefficients for the equalizer based on the sampling rate of the playback stream.
The rendered equalizer impulse response is cached to disk and stored in WAV format. The files can be found in tne foo_dsp_bfir subdirectory in the Foobar profile directory.
In addition to the equalizer, this plug-in also supports convolving with a set of coefficients stored in an impulse file for purposes of digital room correction. The libsndfile library is used to read the sound file, so any format that is supported by that library may be used.
The plug-in supports up to 3 impulse files. The plug-in selects the appropriate impulse file by matching the sampling rate of the impulse file to the playback stream. If the resample checkbox is selected for a given file, the impulse file is resampled to the sampling rate of the playback stream. The resampled file is cached to disk and stored in WAV format.
If more than one impulse file can be used, they are preprocessed by convolving them into a single impulse file. If the equalizer is enabled, it is also convolved with the specified impulse file(s). The resulting impulse response is cached to disk and stored in WAV format.
The equalizer configuration may be saved to and loaded from disk using the DSP configuration panel. The configuration is stored in JSON format.
Note that the FFTW DLL's (libfftw3-3.dll and libfftw3f-3.dll), the libsndfile DLL (libsndfile-1.dll), and the libsamplerate DLL (libsamplerate-0.dll) must be in the same directory as the plug-in DLL for proper operation.
The plug-in features a command-line interface server for remote control of settings. Commands consist of an operation code and data string separated by a space and terminated by a carriage return.
If there is no data string, the current setting is returned, otherwise the current setting is updated and "OK" or "ERR" is returned depending on if the update was successful.
The supported commands are:
EQMx <-200..200> get/set EQ magnitude where x is the band number (0..30)
EQEN <0 | 1> get/set EQ enable
F1EN <0 | 1> get/set file 1 enable
F2EN <0 | 1> get/set file 2 enable
F3EN <0 | 1> get/set file 3 enable
EQLV <-200..200> get/set EQ level
F1LV <-200..200> get/set file 1 level
F2LV <-200..200> get/set file 2 level
F3LV <-200..200> get/set file 3 level
F1FN <file path> get/set file 1 filename
F2FN <file path> get/set file 2 filename
F3FN <file path> get/set file 3 filename
F1MD get file 1 metadata
F2MD get file 2 metadata
F3MD get file 3 metadata
DIR <dir path> list directory
CLOSE close client connection
Command-specific notes:
Setting the filename to "?" (without quotes) indicates no file and resets metadata and file level.
The directory listing returns a JSON string with directory information. If the directory path argument is omitted, the default directory (the application path) is used.
You will need:
Foobar2000 SDK (http://www.foobar2000.org/SDK)
Include files from the Windows Template Library (http://sourceforge.net/projects/wtl/)
Boost C++ libraries (www.boost.org) (You can find pre-built binaries at boostpro.com)
The JSON Spirit, FFTW, libsndfile, and libsamplerate libraries are present in the solution directory or may be obtained from:
http://www.codeproject.com/KB/recipes/JSON_Spirit.aspx
http://www.mega-nerd.com/libsndfile/
Project and solution files are currently for Visual Studio 2010.