ensure that imported regions have names based on the files they are based on

[ardour.git] / libs / ardour / interpolation.cc

diff --git a/libs/ardour/interpolation.cc b/libs/ardour/interpolation.cc
index 9a45d560c0b0ef5813dba8bd3e0f79a50816ff23..1393d8aae81e659c1e4c87b9954307e44c5ce8b3 100644 (file)
--- a/libs/ardour/interpolation.cc
+++ b/libs/ardour/interpolation.cc
@@ -11,16 +11,16 @@ LinearInterpolation::interpolate (int channel, nframes_t nframes, Sample *input,
 {
        // index in the input buffers
        nframes_t   i = 0;
-       
+
        double acceleration;
        double distance = 0.0;
-       
+
        if (_speed != _target_speed) {
                acceleration = _target_speed - _speed;
        } else {
                acceleration = 0.0;
        }
-       
+
        distance = phase[channel];
        for (nframes_t outsample = 0; outsample < nframes; ++outsample) {
                i = floor(distance);
@@ -29,19 +29,19 @@ LinearInterpolation::interpolate (int channel, nframes_t nframes, Sample *input,
                        fractional_phase_part -= 1.0;
                        i++;
                }
-               
+
                if (input && output) {
                // Linearly interpolate into the output buffer
-                       output[outsample] = 
+                       output[outsample] =
                                input[i] * (1.0f - fractional_phase_part) +
                                input[i+1] * fractional_phase_part;
                }
                distance += _speed + acceleration;
        }
-       
+
        i = floor(distance);
        phase[channel] = distance - floor(distance);
-       
+
        return i;
 }
 
@@ -50,34 +50,87 @@ CubicInterpolation::interpolate (int channel, nframes_t nframes, Sample *input,
 {
     // index in the input buffers
     nframes_t   i = 0;
-    
+
     double acceleration;
     double distance = 0.0;
-    
+
     if (_speed != _target_speed) {
         acceleration = _target_speed - _speed;
     } else {
         acceleration = 0.0;
     }
-    
+
     distance = phase[channel];
-    for (nframes_t outsample = 0; outsample < nframes; ++outsample) {
-        i = floor(distance);
-        Sample fractional_phase_part = distance - i;
-        if (fractional_phase_part >= 1.0) {
-            fractional_phase_part -= 1.0;
-            i++;
-        }
-        
-        if (input && output) {
-            // Cubically interpolate into the output buffer
-            output[outsample] = cube_interp(fractional_phase_part, input[i-1], input[i], input[i+1], input[i+2]);
-        }
-        distance += _speed + acceleration;
+
+    if (nframes < 3) {
+           /* no interpolation possible */
+
+           for (i = 0; i < nframes; ++i) {
+                   output[i] = input[i];
+           }
+
+           return nframes;
     }
+
+    /* keep this condition out of the inner loop */
     
+    if (input && output) {
+
+           Sample inm1;
+           
+           if (floor (distance) == 0.0) {
+                   /* best guess for the fake point we have to add to be able to interpolate at i == 0: 
+                      .... maintain slope of first actual segment ...
+                   */
+                   inm1 = input[i] - (input[i+1] - input[i]);
+           } else {
+                   inm1 = input[i-1];
+           }
+
+           for (nframes_t outsample = 0; outsample < nframes; ++outsample) {
+
+                   float f = floor (distance);
+                   float fractional_phase_part = distance - f;
+
+                   /* get the index into the input we should start with */
+
+                   i = lrintf (f);
+
+                   /* fractional_phase_part only reaches 1.0 thanks to float imprecision. In theory
+                      it should always be < 1.0. If it ever >= 1.0, then bump the index we use
+                      and back it off. This is the point where we "skip" an entire sample in the
+                      input, because the phase part has accumulated so much error that we should
+                      really be closer to the next sample. or something like that ...
+                   */
+
+                   if (fractional_phase_part >= 1.0) {
+                           fractional_phase_part -= 1.0;
+                           ++i;
+                   } 
+
+                   // Cubically interpolate into the output buffer: keep this inlined for speed and rely on compiler
+                   // optimization to take care of the rest
+                   // shamelessly ripped from Steve Harris' swh-plugins (ladspa-util.h)
+
+                   output[outsample] = input[i] + 0.5f * fractional_phase_part * (input[i+1] - inm1 +
+                                                         fractional_phase_part * (4.0f * input[i+1] + 2.0f * inm1 - 5.0f * input[i] - input[i+2] +
+                                                               fractional_phase_part * (3.0f * (input[i] - input[i+1]) - inm1 + input[i+2])));
+
+                   distance += _speed + acceleration;
+                   inm1 = input[i];
+           }
+
+    } else {
+
+           /* not sure that this is ever utilized - it implies that one of the input/output buffers is missing */
+
+           for (nframes_t outsample = 0; outsample < nframes; ++outsample) {
+                   distance += _speed + acceleration;
+           }
+    }
+
     i = floor(distance);
     phase[channel] = distance - floor(distance);
-    
+
     return i;
 }