view cpp-qm-dsp/CQInverse.cpp @ 89:25947630486b

More toward inverse CQ

/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
/*
    Constant-Q library
    Copyright (c) 2013-2014 Queen Mary, University of London

    Permission is hereby granted, free of charge, to any person
    obtaining a copy of this software and associated documentation
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    WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

    Except as contained in this notice, the names of the Centre for
    Digital Music; Queen Mary, University of London; and Chris Cannam
    shall not be used in advertising or otherwise to promote the sale,
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*/

#include "CQInverse.h"

#include "CQKernel.h"

#include "dsp/rateconversion/Resampler.h"
#include "maths/MathUtilities.h"
#include "dsp/transforms/FFT.h"

#include <algorithm>
#include <complex>
#include <iostream>
#include <stdexcept>

using std::vector;
using std::complex;
using std::cerr;
using std::endl;

typedef std::complex<double> C;

CQInverse::CQInverse(double sampleRate,
                     double minFreq,
                     double maxFreq,
                     int binsPerOctave) :
    m_sampleRate(sampleRate),
    m_maxFrequency(maxFreq),
    m_minFrequency(minFreq),
    m_binsPerOctave(binsPerOctave),
    m_fft(0)
{
    if (minFreq <= 0.0 || maxFreq <= 0.0) {
        throw std::invalid_argument("Frequency extents must be positive");
    }

    initialise();
}

CQInverse::~CQInverse()
{
    delete m_fft;
    for (int i = 0; i < (int)m_upsamplers.size(); ++i) {
        delete m_upsamplers[i];
    }
    delete m_kernel;
}

double
CQInverse::getMinFrequency() const
{
    return m_p.minFrequency / pow(2.0, m_octaves - 1);
}

double
CQInverse::getBinFrequency(int bin) const
{
    return getMinFrequency() * pow(2, (double(bin) / getBinsPerOctave()));
}

void
CQInverse::initialise()
{
    m_octaves = int(ceil(log2(m_maxFrequency / m_minFrequency)));
    m_kernel = new CQKernel(m_sampleRate, m_maxFrequency, m_binsPerOctave);
    m_p = m_kernel->getProperties();
    
    // Use exact powers of two for resampling rates. They don't have
    // to be related to our actual samplerate: the resampler only
    // cares about the ratio, but it only accepts integer source and
    // target rates, and if we start from the actual samplerate we
    // risk getting non-integer rates for lower octaves

    int sourceRate = pow(2, m_octaves);
    vector<int> latencies;

    // top octave, no resampling
    latencies.push_back(0);
    m_upsamplers.push_back(0);

    for (int i = 1; i < m_octaves; ++i) {

        int factor = pow(2, i);

        Resampler *r = new Resampler
            (sourceRate / factor, sourceRate, 60, 0.02);

	// See ConstantQ.cpp for discussion on latency -- output
	// latency here is at target rate which, this way around, is
	// what we want

        latencies.push_back(r->getLatency());
        m_upsamplers.push_back(r);
    }

    m_bigBlockSize = m_p.fftSize * pow(2, m_octaves - 1);

    //!!! review this later for the hops-dropped stuff
    int maxLatency = 0;
    for (int i = 0; i < m_octaves; ++i) {
	if (latencies[i] > maxLatency) maxLatency = latencies[i];
    }

    m_outputLatency = maxLatency; //!!! for now

    for (int i = 0; i < m_octaves; ++i) {

	// Calculate the difference between the total latency applied
	// across all octaves, and the existing latency due to the
	// upsampler for this octave

        m_buffers.push_back
            (vector<double>(m_outputLatency - latencies[i], 0.0));
    }

    m_fft = new FFTReal(m_p.fftSize);
}

std::vector<double> process(const std::vector<std::vector<double> > &blocks)
{
    // The input data is of the form produced by ConstantQ::process --
    // an unknown number N of columns of varying height. We assert
    // that N is a multiple of atomsPerFrame * 2^(octaves-1).
    //
    // Our procedure:
    // 
    // 1. Slice the list of columns into a set of lists of columns,
    // one per octave, each of width N / (2^octave-1) and height
    // binsPerOctave, containing the values present in that octave
    //
    // 2. Group each octave list by atomsPerFrame columns at a time,
    // and stack these so as to achieve a list, for each octave, of
    // taller columns of height binsPerOctave * atomsPerFrame
    //
    // 3. For each column, take the product with the inverse CQ kernel
    // (which is the conjugate of the forward kernel) and perform an
    // inverse FFT
    //
    // 4. Overlap-add each octave's resynthesised blocks (unwindowed)
    //
    // 5. Resample each octave's overlap-add stream to the original
    // rate, and sum
    
}