Xinterpolation.*: Add old fixed point and double linear interpolation as alternatives

git-svn-id: svn://localhost/ardour2/branches/3.0@5258 d708f5d6-7413-0410-9779-e7cbd77b26cf

libs/ardour/interpolation.cc

@@ -4,8 +4,141 @@
 
 using namespace ARDOUR;
 
-LibSamplerateInterpolation::LibSamplerateInterpolation()  : _speed (1.0L), state (0)
+nframes_t
+FixedPointLinearInterpolation::interpolate (int channel, nframes_t nframes, Sample *input, Sample *output)
 {
+	// the idea behind phase is that when the speed is not 1.0, we have to 
+	// interpolate between samples and then we have to store where we thought we were. 
+	// rather than being at sample N or N+1, we were at N+0.8792922
+	// so the "phase" element, if you want to think about this way, 
+	// varies from 0 to 1, representing the "offset" between samples
+	uint64_t	phase = last_phase[channel];
+	
+	// acceleration
+	int64_t	 phi_delta;
+
+	// phi = fixed point speed
+	if (phi != target_phi) {
+		phi_delta = ((int64_t)(target_phi - phi)) / nframes;
+	} else {
+		phi_delta = 0;
+	}
+	
+	// index in the input buffers
+	nframes_t   i = 0;
+
+	for (nframes_t outsample = 0; outsample < nframes; ++outsample) {
+		i = phase >> 24;
+		Sample fractional_phase_part = (phase & fractional_part_mask) / binary_scaling_factor;
+		
+		if (input && output) {
+			// Linearly interpolate into the output buffer
+			// using fixed point math
+			output[outsample] = 
+				input[i] * (1.0f - fractional_phase_part) +
+				input[i+1] * fractional_phase_part;
+		}
+		
+		phase += phi + phi_delta;
+	}
+
+	last_phase[channel] = (phase & fractional_part_mask);
+	
+	// playback distance
+	return i;
+}
+
+void 
+FixedPointLinearInterpolation::add_channel_to (int input_buffer_size, int output_buffer_size)
+{
+	last_phase.push_back (0);
+}
+
+void 
+FixedPointLinearInterpolation::remove_channel_from ()
+{
+	last_phase.pop_back ();
+}
+
+void
+FixedPointLinearInterpolation::reset() 
+{
+	for(int i = 0; i <= last_phase.size(); i++) {
+		last_phase[i] = 0;
+	}
+}
+
+
+nframes_t
+LinearInterpolation::interpolate (int channel, nframes_t nframes, Sample *input, Sample *output)
+{
+	// 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;
+	}
+	
+	printf("phase before: %lf\n", phase[channel]);
+	distance = phase[channel];
+	for (nframes_t outsample = 0; outsample < nframes; ++outsample) {
+		i = distance;
+		Sample fractional_phase_part = distance - i;
+		if (fractional_phase_part >= 1.0) {
+			fractional_phase_part -= 1.0;
+			i++;
+		}
+		//printf("I: %u, distance: %lf, fractional_phase_part: %lf\n", i, distance, fractional_phase_part);
+		
+		if (input && output) {
+		// Linearly interpolate into the output buffer
+			output[outsample] = 
+				input[i] * (1.0f - fractional_phase_part) +
+				input[i+1] * fractional_phase_part;
+		}
+		//printf("distance before: %lf\n", distance);
+		distance += _speed + acceleration;
+		//printf("distance after: %lf, _speed: %lf\n", distance, _speed);
+	}
+	
+	printf("before assignment: i: %d, distance: %lf\n", i, distance);
+	i = floor(distance);
+	printf("after assignment: i: %d, distance: %16lf\n", i, distance);
+	phase[channel] = distance - floor(distance);
+	printf("speed: %16lf, i after: %d, distance after: %16lf, phase after: %16lf\n", _speed, i, distance, phase[channel]);
+	
+	return i;
+}
+
+void 
+LinearInterpolation::add_channel_to (int input_buffer_size, int output_buffer_size)
+{
+	phase.push_back (0.0);
+}
+
+void 
+LinearInterpolation::remove_channel_from ()
+{
+	phase.pop_back ();
+}
+
+
+void
+LinearInterpolation::reset() 
+{
+	for(int i = 0; i <= phase.size(); i++) {
+		phase[i] = 0.0;
+	}
+}
+
+LibSamplerateInterpolation::LibSamplerateInterpolation() : state (0)
+{
+	_speed = 1.0;
 }
 
 LibSamplerateInterpolation::~LibSamplerateInterpolation() 
@@ -77,12 +210,12 @@ LibSamplerateInterpolation::interpolate (int channel, nframes_t nframes, Sample
 		return 0;
 	}
 	
-	data[channel]->data_in       = input;
-	data[channel]->data_out      = output;
+	data[channel]->data_in	   = input;
+	data[channel]->data_out	  = output;
 	
 	data[channel]->input_frames  = nframes * _speed;
 	data[channel]->output_frames = nframes;
-	data[channel]->src_ratio     = 1.0/_speed; 
+	data[channel]->src_ratio	 = 1.0/_speed; 
 
 	if ((error = src_process (state[channel], data[channel]))) {	
 		printf ("\nError : %s\n\n", src_strerror (error));