Adding upstream version 115.7.0esr.upstream/115.7.0esr

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1108 insertions, 0 deletions

diff --git a/media/libsoundtouch/src/TDStretch.cpp b/media/libsoundtouch/src/TDStretch.cpp
new file mode 100644
index 0000000000..709e979d1d
--- /dev/null
+++ b/media/libsoundtouch/src/TDStretch.cpp
@@ -0,0 +1,1108 @@
+///////////////////////////////////////////////////////////////////////////////
+/// 
+/// Sampled sound tempo changer/time stretch algorithm. Changes the sound tempo 
+/// while maintaining the original pitch by using a time domain WSOLA-like 
+/// method with several performance-increasing tweaks.
+///
+/// Notes : MMX optimized functions reside in a separate, platform-specific 
+/// file, e.g. 'mmx_win.cpp' or 'mmx_gcc.cpp'.
+///
+/// This source file contains OpenMP optimizations that allow speeding up the
+/// corss-correlation algorithm by executing it in several threads / CPU cores 
+/// in parallel. See the following article link for more detailed discussion 
+/// about SoundTouch OpenMP optimizations:
+/// http://www.softwarecoven.com/parallel-computing-in-embedded-mobile-devices
+///
+/// Author        : Copyright (c) Olli Parviainen
+/// Author e-mail : oparviai 'at' iki.fi
+/// SoundTouch WWW: http://www.surina.net/soundtouch
+///
+////////////////////////////////////////////////////////////////////////////////
+//
+// License :
+//
+//  SoundTouch audio processing library
+//  Copyright (c) Olli Parviainen
+//
+//  This library is free software; you can redistribute it and/or
+//  modify it under the terms of the GNU Lesser General Public
+//  License as published by the Free Software Foundation; either
+//  version 2.1 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
+//  Lesser General Public License for more details.
+//
+//  You should have received a copy of the GNU Lesser General Public
+//  License along with this library; if not, write to the Free Software
+//  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+//
+////////////////////////////////////////////////////////////////////////////////
+
+#include <string.h>
+#include <limits.h>
+#include <assert.h>
+#include <math.h>
+#include <float.h>
+
+#include "STTypes.h"
+#include "cpu_detect.h"
+#include "TDStretch.h"
+
+using namespace soundtouch;
+
+#define max(x, y) (((x) > (y)) ? (x) : (y))
+
+/*****************************************************************************
+ *
+ * Constant definitions
+ *
+ *****************************************************************************/
+
+// Table for the hierarchical mixing position seeking algorithm
+const short _scanOffsets[5][24]={
+    { 124,  186,  248,  310,  372,  434,  496,  558,  620,  682,  744, 806,
+      868,  930,  992, 1054, 1116, 1178, 1240, 1302, 1364, 1426, 1488,   0},
+    {-100,  -75,  -50,  -25,   25,   50,   75,  100,    0,    0,    0,   0,
+        0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,   0},
+    { -20,  -15,  -10,   -5,    5,   10,   15,   20,    0,    0,    0,   0,
+        0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,   0},
+    {  -4,   -3,   -2,   -1,    1,    2,    3,    4,    0,    0,    0,   0,
+        0,    0,    0,    0,    0,    0,    0,    0,    0,    0,    0,   0},
+    { 121,  114,   97,  114,   98,  105,  108,   32,  104,   99,  117,  111,
+      116,  100,  110,  117,  111,  115,    0,    0,    0,    0,    0,   0}};
+
+/*****************************************************************************
+ *
+ * Implementation of the class 'TDStretch'
+ *
+ *****************************************************************************/
+
+
+TDStretch::TDStretch() : FIFOProcessor(&outputBuffer)
+{
+    bQuickSeek = false;
+    channels = 2;
+
+    pMidBuffer = NULL;
+    pMidBufferUnaligned = NULL;
+    overlapLength = 0;
+
+    bAutoSeqSetting = true;
+    bAutoSeekSetting = true;
+
+    tempo = 1.0f;
+    setParameters(44100, DEFAULT_SEQUENCE_MS, DEFAULT_SEEKWINDOW_MS, DEFAULT_OVERLAP_MS);
+    setTempo(1.0f);
+
+    clear();
+}
+
+
+
+TDStretch::~TDStretch()
+{
+    delete[] pMidBufferUnaligned;
+}
+
+
+
+// Sets routine control parameters. These control are certain time constants
+// defining how the sound is stretched to the desired duration.
+//
+// 'sampleRate' = sample rate of the sound
+// 'sequenceMS' = one processing sequence length in milliseconds (default = 82 ms)
+// 'seekwindowMS' = seeking window length for scanning the best overlapping 
+//      position (default = 28 ms)
+// 'overlapMS' = overlapping length (default = 12 ms)
+
+void TDStretch::setParameters(int aSampleRate, int aSequenceMS, 
+                              int aSeekWindowMS, int aOverlapMS)
+{
+    // accept only positive parameter values - if zero or negative, use old values instead
+    if (aSampleRate > 0)
+    {
+        if (aSampleRate > 192000) ST_THROW_RT_ERROR("Error: Excessive samplerate");
+        this->sampleRate = aSampleRate;
+    }
+
+    if (aOverlapMS > 0) this->overlapMs = aOverlapMS;
+
+    if (aSequenceMS > 0)
+    {
+        this->sequenceMs = aSequenceMS;
+        bAutoSeqSetting = false;
+    } 
+    else if (aSequenceMS == 0)
+    {
+        // if zero, use automatic setting
+        bAutoSeqSetting = true;
+    }
+
+    if (aSeekWindowMS > 0) 
+    {
+        this->seekWindowMs = aSeekWindowMS;
+        bAutoSeekSetting = false;
+    } 
+    else if (aSeekWindowMS == 0) 
+    {
+        // if zero, use automatic setting
+        bAutoSeekSetting = true;
+    }
+
+    calcSeqParameters();
+
+    calculateOverlapLength(overlapMs);
+
+    // set tempo to recalculate 'sampleReq'
+    setTempo(tempo);
+}
+
+
+
+/// Get routine control parameters, see setParameters() function.
+/// Any of the parameters to this function can be NULL, in such case corresponding parameter
+/// value isn't returned.
+void TDStretch::getParameters(int *pSampleRate, int *pSequenceMs, int *pSeekWindowMs, int *pOverlapMs) const
+{
+    if (pSampleRate)
+    {
+        *pSampleRate = sampleRate;
+    }
+
+    if (pSequenceMs)
+    {
+        *pSequenceMs = (bAutoSeqSetting) ? (USE_AUTO_SEQUENCE_LEN) : sequenceMs;
+    }
+
+    if (pSeekWindowMs)
+    {
+        *pSeekWindowMs = (bAutoSeekSetting) ? (USE_AUTO_SEEKWINDOW_LEN) : seekWindowMs;
+    }
+
+    if (pOverlapMs)
+    {
+        *pOverlapMs = overlapMs;
+    }
+}
+
+
+// Overlaps samples in 'midBuffer' with the samples in 'pInput'
+void TDStretch::overlapMono(SAMPLETYPE *pOutput, const SAMPLETYPE *pInput) const
+{
+    int i;
+    SAMPLETYPE m1, m2;
+
+    m1 = (SAMPLETYPE)0;
+    m2 = (SAMPLETYPE)overlapLength;
+
+    for (i = 0; i < overlapLength ; i ++)
+    {
+        pOutput[i] = (pInput[i] * m1 + pMidBuffer[i] * m2 ) / overlapLength;
+        m1 += 1;
+        m2 -= 1;
+    }
+}
+
+
+
+void TDStretch::clearMidBuffer()
+{
+    memset(pMidBuffer, 0, channels * sizeof(SAMPLETYPE) * overlapLength);
+}
+
+
+void TDStretch::clearInput()
+{
+    inputBuffer.clear();
+    clearMidBuffer();
+    isBeginning = true;
+    maxnorm = 0;
+    maxnormf = 1e8;
+    skipFract = 0;
+}
+
+
+// Clears the sample buffers
+void TDStretch::clear()
+{
+    outputBuffer.clear();
+    clearInput();
+}
+
+
+
+// Enables/disables the quick position seeking algorithm. Zero to disable, nonzero
+// to enable
+void TDStretch::enableQuickSeek(bool enable)
+{
+    bQuickSeek = enable;
+}
+
+
+// Returns nonzero if the quick seeking algorithm is enabled.
+bool TDStretch::isQuickSeekEnabled() const
+{
+    return bQuickSeek;
+}
+
+
+// Seeks for the optimal overlap-mixing position.
+int TDStretch::seekBestOverlapPosition(const SAMPLETYPE *refPos)
+{
+    if (bQuickSeek) 
+    {
+        return seekBestOverlapPositionQuick(refPos);
+    }
+    else 
+    {
+        return seekBestOverlapPositionFull(refPos);
+    }
+}
+
+
+// Overlaps samples in 'midBuffer' with the samples in 'pInputBuffer' at position
+// of 'ovlPos'.
+inline void TDStretch::overlap(SAMPLETYPE *pOutput, const SAMPLETYPE *pInput, uint ovlPos) const
+{
+#ifndef USE_MULTICH_ALWAYS
+    if (channels == 1)
+    {
+        // mono sound.
+        overlapMono(pOutput, pInput + ovlPos);
+    }
+    else if (channels == 2)
+    {
+        // stereo sound
+        overlapStereo(pOutput, pInput + 2 * ovlPos);
+    } 
+    else 
+#endif // USE_MULTICH_ALWAYS
+    {
+        assert(channels > 0);
+        overlapMulti(pOutput, pInput + channels * ovlPos);
+    }
+}
+
+
+// Seeks for the optimal overlap-mixing position. The 'stereo' version of the
+// routine
+//
+// The best position is determined as the position where the two overlapped
+// sample sequences are 'most alike', in terms of the highest cross-correlation
+// value over the overlapping period
+int TDStretch::seekBestOverlapPositionFull(const SAMPLETYPE *refPos) 
+{
+    int bestOffs;
+    double bestCorr;
+    int i;
+    double norm;
+
+    bestCorr = -FLT_MAX;
+    bestOffs = 0;
+
+    // Scans for the best correlation value by testing each possible position
+    // over the permitted range.
+    bestCorr = calcCrossCorr(refPos, pMidBuffer, norm);
+    bestCorr = (bestCorr + 0.1) * 0.75;
+
+    #pragma omp parallel for
+    for (i = 1; i < seekLength; i ++)
+    {
+        double corr;
+        // Calculates correlation value for the mixing position corresponding to 'i'
+#if defined(_OPENMP) || defined(ST_SIMD_AVOID_UNALIGNED)
+        // in parallel OpenMP mode, can't use norm accumulator version as parallel executor won't
+        // iterate the loop in sequential order
+        // in SIMD mode, avoid accumulator version to allow avoiding unaligned positions
+        corr = calcCrossCorr(refPos + channels * i, pMidBuffer, norm);
+#else
+        // In non-parallel version call "calcCrossCorrAccumulate" that is otherwise same
+        // as "calcCrossCorr", but saves time by reusing & updating previously stored 
+        // "norm" value
+        corr = calcCrossCorrAccumulate(refPos + channels * i, pMidBuffer, norm);
+#endif
+        // heuristic rule to slightly favour values close to mid of the range
+        double tmp = (double)(2 * i - seekLength) / (double)seekLength;
+        corr = ((corr + 0.1) * (1.0 - 0.25 * tmp * tmp));
+
+        // Checks for the highest correlation value
+        if (corr > bestCorr) 
+        {
+            // For optimal performance, enter critical section only in case that best value found.
+            // in such case repeat 'if' condition as it's possible that parallel execution may have
+            // updated the bestCorr value in the mean time
+            #pragma omp critical
+            if (corr > bestCorr)
+            {
+                bestCorr = corr;
+                bestOffs = i;
+            }
+        }
+    }
+
+#ifdef SOUNDTOUCH_INTEGER_SAMPLES
+    adaptNormalizer();
+#endif
+
+    // clear cross correlation routine state if necessary (is so e.g. in MMX routines).
+    clearCrossCorrState();
+
+    return bestOffs;
+}
+
+
+// Quick seek algorithm for improved runtime-performance: First roughly scans through the 
+// correlation area, and then scan surroundings of two best preliminary correlation candidates
+// with improved precision
+//
+// Based on testing:
+// - This algorithm gives on average 99% as good match as the full algorithm
+// - this quick seek algorithm finds the best match on ~90% of cases
+// - on those 10% of cases when this algorithm doesn't find best match, 
+//   it still finds on average ~90% match vs. the best possible match
+int TDStretch::seekBestOverlapPositionQuick(const SAMPLETYPE *refPos)
+{
+#define _MIN(a, b)   (((a) < (b)) ? (a) : (b))
+#define SCANSTEP    16
+#define SCANWIND    8
+
+    int bestOffs;
+    int i;
+    int bestOffs2;
+    float bestCorr, corr;
+    float bestCorr2;
+    double norm;
+
+    // note: 'float' types used in this function in case that the platform would need to use software-fp
+
+    bestCorr =
+    bestCorr2 = -FLT_MAX;
+    bestOffs = 
+    bestOffs2 = SCANWIND;
+
+    // Scans for the best correlation value by testing each possible position
+    // over the permitted range. Look for two best matches on the first pass to
+    // increase possibility of ideal match.
+    //
+    // Begin from "SCANSTEP" instead of SCANWIND to make the calculation
+    // catch the 'middlepoint' of seekLength vector as that's the a-priori 
+    // expected best match position
+    //
+    // Roughly:
+    // - 15% of cases find best result directly on the first round,
+    // - 75% cases find better match on 2nd round around the best match from 1st round
+    // - 10% cases find better match on 2nd round around the 2nd-best-match from 1st round
+    for (i = SCANSTEP; i < seekLength - SCANWIND - 1; i += SCANSTEP)
+    {
+        // Calculates correlation value for the mixing position corresponding
+        // to 'i'
+        corr = (float)calcCrossCorr(refPos + channels*i, pMidBuffer, norm);
+        // heuristic rule to slightly favour values close to mid of the seek range
+        float tmp = (float)(2 * i - seekLength - 1) / (float)seekLength;
+        corr = ((corr + 0.1f) * (1.0f - 0.25f * tmp * tmp));
+
+        // Checks for the highest correlation value
+        if (corr > bestCorr)
+        {
+            // found new best match. keep the previous best as 2nd best match
+            bestCorr2 = bestCorr;
+            bestOffs2 = bestOffs;
+            bestCorr = corr;
+            bestOffs = i;
+        }
+        else if (corr > bestCorr2)
+        {
+            // not new best, but still new 2nd best match
+            bestCorr2 = corr;
+            bestOffs2 = i;
+        }
+    }
+
+    // Scans surroundings of the found best match with small stepping
+    int end = _MIN(bestOffs + SCANWIND + 1, seekLength);
+    for (i = bestOffs - SCANWIND; i < end; i++)
+    {
+        if (i == bestOffs) continue;    // this offset already calculated, thus skip
+
+        // Calculates correlation value for the mixing position corresponding
+        // to 'i'
+        corr = (float)calcCrossCorr(refPos + channels*i, pMidBuffer, norm);
+        // heuristic rule to slightly favour values close to mid of the range
+        float tmp = (float)(2 * i - seekLength - 1) / (float)seekLength;
+        corr = ((corr + 0.1f) * (1.0f - 0.25f * tmp * tmp));
+
+        // Checks for the highest correlation value
+        if (corr > bestCorr)
+        {
+            bestCorr = corr;
+            bestOffs = i;
+        }
+    }
+
+    // Scans surroundings of the 2nd best match with small stepping
+    end = _MIN(bestOffs2 + SCANWIND + 1, seekLength);
+    for (i = bestOffs2 - SCANWIND; i < end; i++)
+    {
+        if (i == bestOffs2) continue;    // this offset already calculated, thus skip
+
+        // Calculates correlation value for the mixing position corresponding
+        // to 'i'
+        corr = (float)calcCrossCorr(refPos + channels*i, pMidBuffer, norm);
+        // heuristic rule to slightly favour values close to mid of the range
+        float tmp = (float)(2 * i - seekLength - 1) / (float)seekLength;
+        corr = ((corr + 0.1f) * (1.0f - 0.25f * tmp * tmp));
+
+        // Checks for the highest correlation value
+        if (corr > bestCorr)
+        {
+            bestCorr = corr;
+            bestOffs = i;
+        }
+    }
+
+    // clear cross correlation routine state if necessary (is so e.g. in MMX routines).
+    clearCrossCorrState();
+
+#ifdef SOUNDTOUCH_INTEGER_SAMPLES
+    adaptNormalizer();
+#endif
+
+    return bestOffs;
+}
+
+
+
+
+/// For integer algorithm: adapt normalization factor divider with music so that 
+/// it'll not be pessimistically restrictive that can degrade quality on quieter sections
+/// yet won't cause integer overflows either
+void TDStretch::adaptNormalizer()
+{
+    // Do not adapt normalizer over too silent sequences to avoid averaging filter depleting to
+    // too low values during pauses in music
+    if ((maxnorm > 1000) || (maxnormf > 40000000))
+    { 
+        //norm averaging filter
+        maxnormf = 0.9f * maxnormf + 0.1f * (float)maxnorm;
+
+        if ((maxnorm > 800000000) && (overlapDividerBitsNorm < 16))
+        {
+            // large values, so increase divider
+            overlapDividerBitsNorm++;
+            if (maxnorm > 1600000000) overlapDividerBitsNorm++; // extra large value => extra increase
+        }
+        else if ((maxnormf < 1000000) && (overlapDividerBitsNorm > 0))
+        {
+            // extra small values, decrease divider
+            overlapDividerBitsNorm--;
+        }
+    }
+
+    maxnorm = 0;
+}
+
+
+/// clear cross correlation routine state if necessary 
+void TDStretch::clearCrossCorrState()
+{
+    // default implementation is empty.
+}
+
+
+/// Calculates processing sequence length according to tempo setting
+void TDStretch::calcSeqParameters()
+{
+    // Adjust tempo param according to tempo, so that variating processing sequence length is used
+    // at various tempo settings, between the given low...top limits
+    #define AUTOSEQ_TEMPO_LOW   0.5     // auto setting low tempo range (-50%)
+    #define AUTOSEQ_TEMPO_TOP   2.0     // auto setting top tempo range (+100%)
+
+    // sequence-ms setting values at above low & top tempo
+    #define AUTOSEQ_AT_MIN      90.0
+    #define AUTOSEQ_AT_MAX      40.0
+    #define AUTOSEQ_K           ((AUTOSEQ_AT_MAX - AUTOSEQ_AT_MIN) / (AUTOSEQ_TEMPO_TOP - AUTOSEQ_TEMPO_LOW))
+    #define AUTOSEQ_C           (AUTOSEQ_AT_MIN - (AUTOSEQ_K) * (AUTOSEQ_TEMPO_LOW))
+
+    // seek-window-ms setting values at above low & top tempoq
+    #define AUTOSEEK_AT_MIN     20.0
+    #define AUTOSEEK_AT_MAX     15.0
+    #define AUTOSEEK_K          ((AUTOSEEK_AT_MAX - AUTOSEEK_AT_MIN) / (AUTOSEQ_TEMPO_TOP - AUTOSEQ_TEMPO_LOW))
+    #define AUTOSEEK_C          (AUTOSEEK_AT_MIN - (AUTOSEEK_K) * (AUTOSEQ_TEMPO_LOW))
+
+    #define CHECK_LIMITS(x, mi, ma) (((x) < (mi)) ? (mi) : (((x) > (ma)) ? (ma) : (x)))
+
+    double seq, seek;
+    
+    if (bAutoSeqSetting)
+    {
+        seq = AUTOSEQ_C + AUTOSEQ_K * tempo;
+        seq = CHECK_LIMITS(seq, AUTOSEQ_AT_MAX, AUTOSEQ_AT_MIN);
+        sequenceMs = (int)(seq + 0.5);
+    }
+
+    if (bAutoSeekSetting)
+    {
+        seek = AUTOSEEK_C + AUTOSEEK_K * tempo;
+        seek = CHECK_LIMITS(seek, AUTOSEEK_AT_MAX, AUTOSEEK_AT_MIN);
+        seekWindowMs = (int)(seek + 0.5);
+    }
+
+    // Update seek window lengths
+    seekWindowLength = (sampleRate * sequenceMs) / 1000;
+    if (seekWindowLength < 2 * overlapLength) 
+    {
+        seekWindowLength = 2 * overlapLength;
+    }
+    seekLength = (sampleRate * seekWindowMs) / 1000;
+}
+
+
+
+// Sets new target tempo. Normal tempo = 'SCALE', smaller values represent slower 
+// tempo, larger faster tempo.
+void TDStretch::setTempo(double newTempo)
+{
+    int intskip;
+
+    tempo = newTempo;
+
+    // Calculate new sequence duration
+    calcSeqParameters();
+
+    // Calculate ideal skip length (according to tempo value) 
+    nominalSkip = tempo * (seekWindowLength - overlapLength);
+    intskip = (int)(nominalSkip + 0.5);
+
+    // Calculate how many samples are needed in the 'inputBuffer' to 
+    // process another batch of samples
+    //sampleReq = max(intskip + overlapLength, seekWindowLength) + seekLength / 2;
+    sampleReq = max(intskip + overlapLength, seekWindowLength) + seekLength;
+}
+
+
+
+// Sets the number of channels, 1 = mono, 2 = stereo
+void TDStretch::setChannels(int numChannels)
+{
+    if (!verifyNumberOfChannels(numChannels) ||
+        (channels == numChannels)) return;
+
+    channels = numChannels;
+    inputBuffer.setChannels(channels);
+    outputBuffer.setChannels(channels);
+
+    // re-init overlap/buffer
+    overlapLength=0;
+    setParameters(sampleRate);
+}
+
+
+// nominal tempo, no need for processing, just pass the samples through
+// to outputBuffer
+/*
+void TDStretch::processNominalTempo()
+{
+    assert(tempo == 1.0f);
+
+    if (bMidBufferDirty) 
+    {
+        // If there are samples in pMidBuffer waiting for overlapping,
+        // do a single sliding overlapping with them in order to prevent a 
+        // clicking distortion in the output sound
+        if (inputBuffer.numSamples() < overlapLength) 
+        {
+            // wait until we've got overlapLength input samples
+            return;
+        }
+        // Mix the samples in the beginning of 'inputBuffer' with the 
+        // samples in 'midBuffer' using sliding overlapping 
+        overlap(outputBuffer.ptrEnd(overlapLength), inputBuffer.ptrBegin(), 0);
+        outputBuffer.putSamples(overlapLength);
+        inputBuffer.receiveSamples(overlapLength);
+        clearMidBuffer();
+        // now we've caught the nominal sample flow and may switch to
+        // bypass mode
+    }
+
+    // Simply bypass samples from input to output
+    outputBuffer.moveSamples(inputBuffer);
+}
+*/
+
+
+// Processes as many processing frames of the samples 'inputBuffer', store
+// the result into 'outputBuffer'
+void TDStretch::processSamples()
+{
+    int ovlSkip;
+    int offset = 0;
+    int temp;
+
+    /* Removed this small optimization - can introduce a click to sound when tempo setting
+       crosses the nominal value
+    if (tempo == 1.0f) 
+    {
+        // tempo not changed from the original, so bypass the processing
+        processNominalTempo();
+        return;
+    }
+    */
+
+    // Process samples as long as there are enough samples in 'inputBuffer'
+    // to form a processing frame.
+    while ((int)inputBuffer.numSamples() >= sampleReq) 
+    {
+        if (isBeginning == false)
+        {
+            // apart from the very beginning of the track, 
+            // scan for the best overlapping position & do overlap-add
+            offset = seekBestOverlapPosition(inputBuffer.ptrBegin());
+
+            // Mix the samples in the 'inputBuffer' at position of 'offset' with the 
+            // samples in 'midBuffer' using sliding overlapping
+            // ... first partially overlap with the end of the previous sequence
+            // (that's in 'midBuffer')
+            overlap(outputBuffer.ptrEnd((uint)overlapLength), inputBuffer.ptrBegin(), (uint)offset);
+            outputBuffer.putSamples((uint)overlapLength);
+            offset += overlapLength;
+        }
+        else
+        {
+            // Adjust processing offset at beginning of track by not perform initial overlapping
+            // and compensating that in the 'input buffer skip' calculation
+            isBeginning = false;
+            int skip = (int)(tempo * overlapLength + 0.5 * seekLength + 0.5);
+
+            #ifdef ST_SIMD_AVOID_UNALIGNED
+            // in SIMD mode, round the skip amount to value corresponding to aligned memory address
+            if (channels == 1)
+            {
+                skip &= -4;
+            }
+            else if (channels == 2)
+            {
+                skip &= -2;
+            }
+            #endif
+            skipFract -= skip;
+            if (skipFract <= -nominalSkip)
+            {
+                skipFract = -nominalSkip;
+            }
+        }
+
+        // ... then copy sequence samples from 'inputBuffer' to output:
+
+        // crosscheck that we don't have buffer overflow...
+        if ((int)inputBuffer.numSamples() < (offset + seekWindowLength - overlapLength))
+        {
+            continue;    // just in case, shouldn't really happen
+        }
+
+        // length of sequence
+        temp = (seekWindowLength - 2 * overlapLength);
+        outputBuffer.putSamples(inputBuffer.ptrBegin() + channels * offset, (uint)temp);
+
+        // Copies the end of the current sequence from 'inputBuffer' to 
+        // 'midBuffer' for being mixed with the beginning of the next 
+        // processing sequence and so on
+        assert((offset + temp + overlapLength) <= (int)inputBuffer.numSamples());
+        memcpy(pMidBuffer, inputBuffer.ptrBegin() + channels * (offset + temp), 
+            channels * sizeof(SAMPLETYPE) * overlapLength);
+
+        // Remove the processed samples from the input buffer. Update
+        // the difference between integer & nominal skip step to 'skipFract'
+        // in order to prevent the error from accumulating over time.
+        skipFract += nominalSkip;   // real skip size
+        ovlSkip = (int)skipFract;   // rounded to integer skip
+        skipFract -= ovlSkip;       // maintain the fraction part, i.e. real vs. integer skip
+        inputBuffer.receiveSamples((uint)ovlSkip);
+    }
+}
+
+
+// Adds 'numsamples' pcs of samples from the 'samples' memory position into
+// the input of the object.
+void TDStretch::putSamples(const SAMPLETYPE *samples, uint nSamples)
+{
+    // Add the samples into the input buffer
+    inputBuffer.putSamples(samples, nSamples);
+    // Process the samples in input buffer
+    processSamples();
+}
+
+
+
+/// Set new overlap length parameter & reallocate RefMidBuffer if necessary.
+void TDStretch::acceptNewOverlapLength(int newOverlapLength)
+{
+    int prevOvl;
+
+    assert(newOverlapLength >= 0);
+    prevOvl = overlapLength;
+    overlapLength = newOverlapLength;
+
+    if (overlapLength > prevOvl)
+    {
+        delete[] pMidBufferUnaligned;
+
+        pMidBufferUnaligned = new SAMPLETYPE[overlapLength * channels + 16 / sizeof(SAMPLETYPE)];
+        // ensure that 'pMidBuffer' is aligned to 16 byte boundary for efficiency
+        pMidBuffer = (SAMPLETYPE *)SOUNDTOUCH_ALIGN_POINTER_16(pMidBufferUnaligned);
+
+        clearMidBuffer();
+    }
+}
+
+
+// Operator 'new' is overloaded so that it automatically creates a suitable instance 
+// depending on if we've a MMX/SSE/etc-capable CPU available or not.
+void * TDStretch::operator new(size_t s)
+{
+    // Notice! don't use "new TDStretch" directly, use "newInstance" to create a new instance instead!
+    ST_THROW_RT_ERROR("Error in TDStretch::new: Don't use 'new TDStretch' directly, use 'newInstance' member instead!");
+    return newInstance();
+}
+
+
+TDStretch * TDStretch::newInstance()
+{
+#if defined(SOUNDTOUCH_ALLOW_MMX) || defined(SOUNDTOUCH_ALLOW_SSE)
+    uint uExtensions;
+
+    uExtensions = detectCPUextensions();
+#endif
+
+    // Check if MMX/SSE instruction set extensions supported by CPU
+
+#ifdef SOUNDTOUCH_ALLOW_MMX
+    // MMX routines available only with integer sample types
+    if (uExtensions & SUPPORT_MMX)
+    {
+        return ::new TDStretchMMX;
+    }
+    else
+#endif // SOUNDTOUCH_ALLOW_MMX
+
+
+#ifdef SOUNDTOUCH_ALLOW_SSE
+    if (uExtensions & SUPPORT_SSE)
+    {
+        // SSE support
+        return ::new TDStretchSSE;
+    }
+    else
+#endif // SOUNDTOUCH_ALLOW_SSE
+
+    {
+        // ISA optimizations not supported, use plain C version
+        return ::new TDStretch;
+    }
+}
+
+
+//////////////////////////////////////////////////////////////////////////////
+//
+// Integer arithmetic specific algorithm implementations.
+//
+//////////////////////////////////////////////////////////////////////////////
+
+#ifdef SOUNDTOUCH_INTEGER_SAMPLES
+
+// Overlaps samples in 'midBuffer' with the samples in 'input'. The 'Stereo' 
+// version of the routine.
+void TDStretch::overlapStereo(short *poutput, const short *input) const
+{
+    int i;
+    short temp;
+    int cnt2;
+
+    for (i = 0; i < overlapLength ; i ++)
+    {
+        temp = (short)(overlapLength - i);
+        cnt2 = 2 * i;
+        poutput[cnt2] = (input[cnt2] * i + pMidBuffer[cnt2] * temp )  / overlapLength;
+        poutput[cnt2 + 1] = (input[cnt2 + 1] * i + pMidBuffer[cnt2 + 1] * temp ) / overlapLength;
+    }
+}
+
+
+// Overlaps samples in 'midBuffer' with the samples in 'input'. The 'Multi'
+// version of the routine.
+void TDStretch::overlapMulti(short *poutput, const short *input) const
+{
+    short m1;
+    int i = 0;
+
+    for (m1 = 0; m1 < overlapLength; m1 ++)
+    {
+        short m2 = (short)(overlapLength - m1);
+        for (int c = 0; c < channels; c ++)
+        {
+            poutput[i] = (input[i] * m1 + pMidBuffer[i] * m2)  / overlapLength;
+            i++;
+        }
+    }
+}
+
+// Calculates the x having the closest 2^x value for the given value
+static int _getClosest2Power(double value)
+{
+    return (int)(log(value) / log(2.0) + 0.5);
+}
+
+
+/// Calculates overlap period length in samples.
+/// Integer version rounds overlap length to closest power of 2
+/// for a divide scaling operation.
+void TDStretch::calculateOverlapLength(int aoverlapMs)
+{
+    int newOvl;
+
+    assert(aoverlapMs >= 0);
+
+    // calculate overlap length so that it's power of 2 - thus it's easy to do
+    // integer division by right-shifting. Term "-1" at end is to account for 
+    // the extra most significatnt bit left unused in result by signed multiplication 
+    overlapDividerBitsPure = _getClosest2Power((sampleRate * aoverlapMs) / 1000.0) - 1;
+    if (overlapDividerBitsPure > 9) overlapDividerBitsPure = 9;
+    if (overlapDividerBitsPure < 3) overlapDividerBitsPure = 3;
+    newOvl = (int)pow(2.0, (int)overlapDividerBitsPure + 1);    // +1 => account for -1 above
+
+    acceptNewOverlapLength(newOvl);
+
+    overlapDividerBitsNorm = overlapDividerBitsPure;
+
+    // calculate sloping divider so that crosscorrelation operation won't 
+    // overflow 32-bit register. Max. sum of the crosscorrelation sum without 
+    // divider would be 2^30*(N^3-N)/3, where N = overlap length
+    slopingDivider = (newOvl * newOvl - 1) / 3;
+}
+
+
+double TDStretch::calcCrossCorr(const short *mixingPos, const short *compare, double &norm)
+{
+    long corr;
+    unsigned long lnorm;
+    int i;
+
+    #ifdef ST_SIMD_AVOID_UNALIGNED
+        // in SIMD mode skip 'mixingPos' positions that aren't aligned to 16-byte boundary
+        if (((ulongptr)mixingPos) & 15) return -1e50;
+    #endif
+
+    // hint compiler autovectorization that loop length is divisible by 8
+    int ilength = (channels * overlapLength) & -8;
+
+    corr = lnorm = 0;
+    // Same routine for stereo and mono
+    for (i = 0; i < ilength; i += 2)
+    {
+        corr += (mixingPos[i] * compare[i] + 
+                 mixingPos[i + 1] * compare[i + 1]) >> overlapDividerBitsNorm;
+        lnorm += (mixingPos[i] * mixingPos[i] + 
+                  mixingPos[i + 1] * mixingPos[i + 1]) >> overlapDividerBitsNorm;
+        // do intermediate scalings to avoid integer overflow
+    }
+
+    if (lnorm > maxnorm)
+    {
+        // modify 'maxnorm' inside critical section to avoid multi-access conflict if in OpenMP mode
+        #pragma omp critical
+        if (lnorm > maxnorm)
+        {
+            maxnorm = lnorm;
+        }
+    }
+    // Normalize result by dividing by sqrt(norm) - this step is easiest 
+    // done using floating point operation
+    norm = (double)lnorm;
+    return (double)corr / sqrt((norm < 1e-9) ? 1.0 : norm);
+}
+
+
+/// Update cross-correlation by accumulating "norm" coefficient by previously calculated value
+double TDStretch::calcCrossCorrAccumulate(const short *mixingPos, const short *compare, double &norm)
+{
+    long corr;
+    long lnorm;
+    int i;
+
+    // hint compiler autovectorization that loop length is divisible by 8
+    int ilength = (channels * overlapLength) & -8;
+
+    // cancel first normalizer tap from previous round
+    lnorm = 0;
+    for (i = 1; i <= channels; i ++)
+    {
+        lnorm -= (mixingPos[-i] * mixingPos[-i]) >> overlapDividerBitsNorm;
+    }
+
+    corr = 0;
+    // Same routine for stereo and mono.
+    for (i = 0; i < ilength; i += 2) 
+    {
+        corr += (mixingPos[i] * compare[i] + 
+                 mixingPos[i + 1] * compare[i + 1]) >> overlapDividerBitsNorm;
+    }
+
+    // update normalizer with last samples of this round
+    for (int j = 0; j < channels; j ++)
+    {
+        i --;
+        lnorm += (mixingPos[i] * mixingPos[i]) >> overlapDividerBitsNorm;
+    }
+
+    norm += (double)lnorm;
+    if (norm > maxnorm)
+    {
+        maxnorm = (unsigned long)norm;
+    }
+
+    // Normalize result by dividing by sqrt(norm) - this step is easiest 
+    // done using floating point operation
+    return (double)corr / sqrt((norm < 1e-9) ? 1.0 : norm);
+}
+
+#endif // SOUNDTOUCH_INTEGER_SAMPLES
+
+//////////////////////////////////////////////////////////////////////////////
+//
+// Floating point arithmetic specific algorithm implementations.
+//
+
+#ifdef SOUNDTOUCH_FLOAT_SAMPLES
+
+// Overlaps samples in 'midBuffer' with the samples in 'pInput'
+void TDStretch::overlapStereo(float *pOutput, const float *pInput) const
+{
+    int i;
+    float fScale;
+    float f1;
+    float f2;
+
+    fScale = 1.0f / (float)overlapLength;
+
+    f1 = 0;
+    f2 = 1.0f;
+
+    for (i = 0; i < 2 * (int)overlapLength ; i += 2) 
+    {
+        pOutput[i + 0] = pInput[i + 0] * f1 + pMidBuffer[i + 0] * f2;
+        pOutput[i + 1] = pInput[i + 1] * f1 + pMidBuffer[i + 1] * f2;
+
+        f1 += fScale;
+        f2 -= fScale;
+    }
+}
+
+
+// Overlaps samples in 'midBuffer' with the samples in 'input'. 
+void TDStretch::overlapMulti(float *pOutput, const float *pInput) const
+{
+    int i;
+    float fScale;
+    float f1;
+    float f2;
+
+    fScale = 1.0f / (float)overlapLength;
+
+    f1 = 0;
+    f2 = 1.0f;
+
+    i=0;
+    for (int i2 = 0; i2 < overlapLength; i2 ++)
+    {
+        // note: Could optimize this slightly by taking into account that always channels > 2
+        for (int c = 0; c < channels; c ++)
+        {
+            pOutput[i] = pInput[i] * f1 + pMidBuffer[i] * f2;
+            i++;
+        }
+        f1 += fScale;
+        f2 -= fScale;
+    }
+}
+
+
+/// Calculates overlapInMsec period length in samples.
+void TDStretch::calculateOverlapLength(int overlapInMsec)
+{
+    int newOvl;
+
+    assert(overlapInMsec >= 0);
+    newOvl = (sampleRate * overlapInMsec) / 1000;
+    if (newOvl < 16) newOvl = 16;
+
+    // must be divisible by 8
+    newOvl -= newOvl % 8;
+
+    acceptNewOverlapLength(newOvl);
+}
+
+
+/// Calculate cross-correlation
+double TDStretch::calcCrossCorr(const float *mixingPos, const float *compare, double &anorm)
+{
+    float corr;
+    float norm;
+    int i;
+
+    #ifdef ST_SIMD_AVOID_UNALIGNED
+        // in SIMD mode skip 'mixingPos' positions that aren't aligned to 16-byte boundary
+        if (((ulongptr)mixingPos) & 15) return -1e50;
+    #endif
+
+    // hint compiler autovectorization that loop length is divisible by 8
+    int ilength = (channels * overlapLength) & -8;
+
+    corr = norm = 0;
+    // Same routine for stereo and mono
+    for (i = 0; i < ilength; i ++)
+    {
+        corr += mixingPos[i] * compare[i];
+        norm += mixingPos[i] * mixingPos[i];
+    }
+
+    anorm = norm;
+    return corr / sqrt((norm < 1e-9 ? 1.0 : norm));
+}
+
+
+/// Update cross-correlation by accumulating "norm" coefficient by previously calculated value
+double TDStretch::calcCrossCorrAccumulate(const float *mixingPos, const float *compare, double &norm)
+{
+    float corr;
+    int i;
+
+    corr = 0;
+
+    // cancel first normalizer tap from previous round
+    for (i = 1; i <= channels; i ++)
+    {
+        norm -= mixingPos[-i] * mixingPos[-i];
+    }
+
+    // hint compiler autovectorization that loop length is divisible by 8
+    int ilength = (channels * overlapLength) & -8;
+
+    // Same routine for stereo and mono
+    for (i = 0; i < ilength; i ++)
+    {
+        corr += mixingPos[i] * compare[i];
+    }
+
+    // update normalizer with last samples of this round
+    for (int j = 0; j < channels; j ++)
+    {
+        i --;
+        norm += mixingPos[i] * mixingPos[i];
+    }
+
+    return corr / sqrt((norm < 1e-9 ? 1.0 : norm));
+}
+
+
+#endif // SOUNDTOUCH_FLOAT_SAMPLES