1 files changed, 305 insertions, 0 deletions
diff --git a/flow/resample.cc b/flow/resample.cc
new file mode 100644
index 0000000..45cd099
--- /dev/null
+++ b/flow/resample.cc
@@ -0,0 +1,305 @@
+    /*
+
+    Copyright (C) 2000 Stefan Westerfeld
+                       stefan@space.twc.de
+
+    This library is free software; you can redistribute it and/or
+    modify it under the terms of the GNU Library General Public
+    License as published by the Free Software Foundation; either
+    version 2 of the License, or (at your option) any later version.
+  
+    This library is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+    Library General Public License for more details.
+   
+    You should have received a copy of the GNU Library General Public License
+    along with this library; see the file COPYING.LIB.  If not, write to
+    the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+    Boston, MA 02111-1307, USA.
+
+    */
+
+#include "resample.h"
+#include "debug.h"
+#include <math.h>
+#include <assert.h>
+#include <stdio.h>
+
+#define compose_16le(first,second) \
+    (((((second)+128)&0xff) << 8)+(first))
+ 
+#define compose_16be(first,second) \
+    (((((first)+128)&0xff) << 8)+(second))
+
+#define conv_16_float(x) \
+    ((float)((x)-32768)/32768.0)                                                
+
+#define conv_8_float(x) \
+	((float)((x)-128)/128.0)
+
+using namespace Arts;
+
+class Arts::ResamplerPrivate {
+public:
+	bool underrun;	
+	Resampler::Endianness endianness;
+};
+
+const unsigned int Resampler::bufferSize;
+const unsigned int Resampler::bufferWrap;
+
+Resampler::Resampler(Refiller *refiller) :
+	dropBytes(0), refiller(refiller), pos(0.0), step(1.0), channels(2),
+	bits(16),
+	block(0), haveBlock(-1)
+{
+	d = new ResamplerPrivate();
+	d->underrun = false;
+	d->endianness = littleEndian;
+	updateSampleSize();
+}
+
+Resampler::~Resampler()
+{
+	delete d;
+}
+
+void Resampler::updateSampleSize()
+{
+	sampleSize = channels * bits / 8;
+	bufferSamples = bufferSize / sampleSize;
+}
+
+void Resampler::setStep(double newStep)
+{
+	arts_return_if_fail(newStep > 0);
+
+	step = newStep;
+}
+
+void Resampler::setChannels(int newChannels)
+{
+	arts_return_if_fail(newChannels == 1 || newChannels == 2);
+
+	channels = newChannels;
+	updateSampleSize();
+}
+
+void Resampler::setBits(int newBits)
+{
+	arts_return_if_fail(newBits == 8 || newBits == 16);
+
+	bits = newBits;
+	updateSampleSize();
+}
+
+void Resampler::setEndianness(Endianness newEndianness)
+{
+	arts_return_if_fail(newEndianness == bigEndian || newEndianness == littleEndian);
+
+	d->endianness = newEndianness;
+}
+
+bool Resampler::underrun()
+{
+	return d->underrun;
+}
+
+void Resampler::ensureRefill()
+{
+	if(haveBlock == block) return;
+
+	unsigned long missing;
+	if(block == 0)
+	{
+		missing = bufferSize+sampleSize
+				- refiller->read(buffer,bufferSize+sampleSize);
+
+		d->underrun = (missing == bufferSize+sampleSize);
+	}
+	else
+	{
+		/*
+		 * try to drop away "half-sample" reads from the last refill
+		 */
+		if(dropBytes > 0)
+			dropBytes -= refiller->read(buffer,dropBytes);
+
+		/*
+		 * only if this worked there is hope that we can read sane data
+		 */
+		if(dropBytes == 0)
+		{
+			missing = bufferSize
+					- refiller->read(&buffer[sampleSize], bufferSize);
+
+			d->underrun = (missing == bufferSize);
+		}
+		else
+		{
+			missing = bufferSize;
+			d->underrun = true;
+		}
+	}
+	haveBlock++;
+	assert(haveBlock == block);
+
+	/*
+	 * If we don't have enough input to fill the block fully, it might be
+	 * that the input stall occurred in the middle of a sample. For instance,
+	 * if samples are 4 bytes long, it might be that we would have needed
+	 * 13 more bytes to do a full refill.
+	 *
+	 * In this situation, there are four samples and one byte missing to
+	 * refill the buffer - the one byte is what we need to care about here:
+	 * on the next read, we'll have one byte too much (if we simply ignore
+	 * the fact, we end up with misaligned reading, causing noise, or
+	 * swapped stereo channels or similar).
+	 *
+	 * So we set dropBytes here, which is a variable which indicates how
+	 * many bytes to drop away upon next refill.
+	 */
+	if(missing & (sampleSize - 1))
+		dropBytes = missing & (sampleSize - 1);
+
+	unsigned int i = 0, wrap = (block == 0)?0:sampleSize;
+	if(bits == 16)
+	{
+		// wrap the last part of the buffer back to the beginning (history)
+		while(i<wrap)
+		{
+			fbuffer[i/2] = fbuffer[(bufferSize+i)/2];
+			i += 2;
+		}
+
+		// convert data from incoming
+		if(d->endianness == littleEndian)
+		{
+			while(i<bufferSize+sampleSize-missing)
+			{
+				fbuffer[i/2] = conv_16_float(compose_16le(buffer[i],buffer[i+1]));
+				i += 2;
+			}
+		}
+		else
+		{
+			while(i<bufferSize+sampleSize-missing)
+			{
+				fbuffer[i/2] = conv_16_float(compose_16be(buffer[i],buffer[i+1]));
+				i += 2;
+			}
+		}
+
+		// fill up missing bytes with zero samples
+		while(i<bufferSize+sampleSize)
+		{
+			fbuffer[i/2] = 0.0;
+			i += 2;
+		}
+	}
+	else if(bits == 8)
+	{
+		// wrap the last part of the buffer back to the beginning (history)
+		while(i<wrap)
+		{
+			fbuffer[i] = fbuffer[bufferSize+i];
+			i++;
+		}
+
+		// convert data from incoming
+		while(i<bufferSize+sampleSize-missing)
+		{
+			fbuffer[i] = conv_8_float(buffer[i]);
+			i++;
+		}
+
+		// fill up missing bytes with zero samples
+		while(i<bufferSize+sampleSize)
+		{
+			fbuffer[i++] = 0.0;
+		}
+	}
+	else
+	{
+		assert(false);
+	}
+}
+
+#define RESAMPLER_STEP()							\
+	pos += step;									\
+	i++;											\
+	while(pos >= bufferSamples)						\
+	{												\
+		pos -= bufferSamples;						\
+		block++;									\
+		ensureRefill();								\
+	}
+
+void Resampler::run(float *left, float *right, unsigned long samples)
+{
+	ensureRefill();
+	unsigned long i = 0;
+	double delta = step - floor(step);
+	bool interpolate = fabs(delta) > 0.001;
+
+	if(channels == 2 && interpolate)
+	{
+		while(i < samples)
+		{
+			double error = pos - floor(pos);
+			unsigned long offset = 2*(unsigned long)pos;
+
+			left[i]  = fbuffer[offset+0]*(1.0-error)+fbuffer[offset+2]*error;
+			right[i] = fbuffer[offset+1]*(1.0-error)+fbuffer[offset+3]*error;
+			RESAMPLER_STEP();
+		}
+	}
+	else if(channels == 1 && interpolate)
+	{
+		while(i < samples)
+		{
+			double error = pos - floor(pos);
+			unsigned long offset = (unsigned long)pos;
+
+			left[i] = right[i] = fbuffer[offset]*(1.0-error)
+							   + fbuffer[offset+1]*error;
+			RESAMPLER_STEP();
+		}
+	}
+	else if(channels == 2)
+	{
+		while(i < samples)
+		{
+			unsigned long offset = 2*(unsigned long)pos;
+
+			left[i]  = fbuffer[offset+0];
+			right[i] = fbuffer[offset+1];
+			RESAMPLER_STEP();
+		}
+	}
+	else if(channels == 1)
+	{
+		while(i < samples)
+		{
+			unsigned long offset = (unsigned long)pos;
+
+			left[i] = right[i] = fbuffer[offset];
+			RESAMPLER_STEP();
+		}
+	}
+	else
+	{
+		assert(false);
+	}
+}
+
+Refiller::~Refiller()
+{
+}
+
+#undef RESAMPLER_STEP
+#undef compose_16le
+#undef compose_16be
+#undef conv_16_float
+#undef conv_8_float