remove Session::get_nth_stripable.cc

[ardour.git] / libs / ardour / ardour / dsp_filter.h

diff --git a/libs/ardour/ardour/dsp_filter.h b/libs/ardour/ardour/dsp_filter.h
index 0ecf08cf44f1752e164e9d57807e8175d11e8853..994d8725ea418576c6c3edacfacd779f49f8dcb1 100644 (file)
--- a/libs/ardour/ardour/dsp_filter.h
+++ b/libs/ardour/ardour/dsp_filter.h
@@ -27,18 +27,20 @@
 
 namespace ARDOUR { namespace DSP {
 
-       /** C Shared Memory
+       /** C/C++ Shared Memory
         *
-        * A convenience class representing a C array or float[] or int32_t[]
+        * A convenience class representing a C array of float[] or int32_t[]
         * data values. This is useful for lua scripts to perform DSP operations
-        * directly using C, C++.
-        * Access to this memory area is always 4 byte aligned: float, int.
+        * directly using C/C++ with CPU Hardware acceleration.
         *
-        * This memory area can also be shared between different instances.
+        * Access to this memory area is always 4 byte aligned. The data
+        * is interpreted either as float or as int.
+        *
+        * This memory area can also be shared between different instances
+        * or the same lua plugin (DSP, GUI).
         *
         * Since memory allocation is not realtime safe it should be
         * allocated during dsp_init() or dsp_configure().
-        *
         * The memory is free()ed automatically when the lua instance is
         * destroyed.
         */
@@ -191,7 +193,7 @@ namespace ARDOUR { namespace DSP {
        };
 
        /** Biquad Filter */
-       class LIBARDOUR_API BiQuad {
+       class LIBARDOUR_API Biquad {
                public:
                        enum Type {
                                LowPass,
@@ -209,8 +211,8 @@ namespace ARDOUR { namespace DSP {
                         *
                         * @param samplerate Samplerate
                         */
-                       BiQuad (double samplerate);
-                       BiQuad (const BiQuad &other);
+                       Biquad (double samplerate);
+                       Biquad (const Biquad &other);
 
                        /** process audio data
                         *
@@ -220,12 +222,19 @@ namespace ARDOUR { namespace DSP {
                        void run (float *data, const uint32_t n_samples);
                        /** setup filter, compute coefficients
                         *
-                        * @param t filter type
+                        * @param t filter type (LowPass, HighPass, etc)
                         * @param freq filter frequency
                         * @param Q filter quality
                         * @param gain filter gain
                         */
                        void compute (Type t, double freq, double Q, double gain);
+
+                       /** filter transfer function (filter response for spectrum visualization)
+                        * @param freq frequency
+                        * @return gain at given frequency in dB (clamped to -120..+120)
+                        */
+                       float dB_at_freq (float freq) const;
+
                        /** reset filter state */
                        void reset () { _z1 = _z2 = 0.0; }
                private: