view cpp-qm-dsp/ConstantQ.cpp @ 44:337d3b324c75

Some work on alignment

#include "ConstantQ.h"

#include "CQKernel.h"

#include "qm-dsp/dsp/rateconversion/Resampler.h"
#include "qm-dsp/maths/MathUtilities.h"
#include "qm-dsp/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;

ConstantQ::ConstantQ(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();
}

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

void
ConstantQ::initialise()
{
    m_octaves = int(ceil(log2(m_maxFrequency / m_minFrequency)));
    double actualMinFreq =
        (m_maxFrequency / pow(2.0, m_octaves)) * pow(2.0, 1.0/m_binsPerOctave);

    cerr << "actual min freq = " << actualMinFreq << endl;

    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_decimators.push_back(0);

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

        int factor = pow(2, i);

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

        // We need to adapt the latencies so as to get the first input
        // sample to be aligned, in time, at the decimator output
        // across all octaves.
        // 
        // Our decimator uses a linear phase filter, but being causal
        // it is not zero phase: it has a latency that depends on the
        // decimation factor. Those latencies have been calculated
        // per-octave and are available to us in the latencies
        // array. Left to its own devices, the first input sample will
        // appear at output sample 0 in the highest octave (where no
        // decimation is needed), sample number latencies[1] in the
        // next octave down, latencies[2] in the next one, etc. We get
        // to apply some artificial per-octave latency after the
        // decimator in the processing chain, in order to compensate
        // for the differing latencies associated with different
        // decimation factors. How much should we insert?
        //
        // The outputs of the decimators are at different rates (in
        // terms of the relation between clock time and samples) and
        // we want them aligned in terms of time. So, for example, a
        // latency of 10 samples with a decimation factor of 2 is
        // equivalent to a latency of 20 with no decimation -- they
        // both result in the first output sample happening at the
        // same equivalent time in milliseconds.
	// 
	// So here we record the latency added by the decimator, in
	// terms of the sample rate of the undecimated signal. Then we
	// use that to compensate in a moment, when we've discovered
	// what the longest latency across all octaves is.

        latencies.push_back(r->getLatency() * factor);
        m_decimators.push_back(r);
    }

    //!!! should be multiple of the kernel fft size?
    int maxLatency = *std::max_element(latencies.begin(), latencies.end());
    m_totalLatency = MathUtilities::nextPowerOfTwo(maxLatency);
    cerr << "total latency = " << m_totalLatency << endl;
        //!!! should also round up so that total latency is a multiple of the big block size

    int emptyHops = m_p.firstCentre / m_p.atomSpacing; //!!! round?

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

	double factor = pow(2, i);

	// And here (see comment above) we calculate the difference
	// between the total latency applied across all octaves, and
	// the existing latency due to the decimator for this octave,
	// and then convert it back into the sample rate appropriate
	// for the output latency of this decimator.

	double extraLatency = double(m_totalLatency - latencies[i]) / factor;

        int pad = m_p.fftSize * pow(2, m_octaves-i-1);

//!!! This appears to be about right, by visual inspection. But why?
	int pad2 = 0;
	for (int j = 0; j < i; ++j) {
	    pad2 += 9;
	}


        int drop = emptyHops * pow(2, m_octaves-i-1) - emptyHops;



	cerr << "for octave " << i << ", latency for decimator = " << extraLatency << ", fixed padding = " << pad << ", visual inspection pad = " << pad2 << ", hops to drop would be " << drop << ", 2^i = " << pow(2, i) << ", 2^o-i = " << pow(2,m_octaves-i-1) << endl;

	extraLatency += pad + pad2;

	cerr << "then extraLatency -> " << extraLatency << endl;

        m_buffers.push_back
            (vector<double>(int(round(extraLatency)), 0.0));
    }

    m_fft = new FFTReal(m_p.fftSize);
    m_bigBlockSize = m_p.fftSize * pow(2, m_octaves) / 2;

    cerr << "m_bigBlockSize = " << m_bigBlockSize << " for " << m_octaves << " octaves" << endl;
}

vector<vector<double> > 
ConstantQ::process(const vector<double> &td)
{
    m_buffers[0].insert(m_buffers[0].end(), td.begin(), td.end());

    for (int i = 1; i < m_octaves; ++i) {
        vector<double> dec = m_decimators[i]->process(td.data(), td.size());
        m_buffers[i].insert(m_buffers[i].end(), dec.begin(), dec.end());
    }

    vector<vector<double> > out;

    //!!!! need some mechanism for handling remaining samples at the end

    while ((int)m_buffers[0].size() >= m_bigBlockSize) {

        int base = out.size();
        int totalColumns = pow(2, m_octaves - 1) * m_p.atomsPerFrame;
        cerr << "totalColumns = " << totalColumns << endl;
        for (int i = 0; i < totalColumns; ++i) {
            out.push_back(vector<double>(m_p.binsPerOctave * m_octaves, 0.0));
        }

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

            int blocksThisOctave = pow(2, (m_octaves - octave - 1));
//          cerr << "octave " << octave+1 << " of " << m_octaves << ", n = " << blocksThisOctave << endl;

            for (int b = 0; b < blocksThisOctave; ++b) {
                vector<vector<double> > block = processOctaveBlock(octave);
                
                for (int j = 0; j < m_p.atomsPerFrame; ++j) {

		    for (int k = 0; k < pow(2, octave); ++k) {

			int target = base + k +
			    (b * (totalColumns / blocksThisOctave) + 
			     (j * ((totalColumns / blocksThisOctave) /
				   m_p.atomsPerFrame)));

			for (int i = 0; i < m_p.binsPerOctave; ++i) {
			    out[target][m_p.binsPerOctave * octave + i] = 
				block[j][m_p.binsPerOctave - i - 1];
			}
		    }
                }
            }
        }
    }
    
    return out;
}

vector<vector<double> >
ConstantQ::getRemainingBlocks()
{
    int n = m_bigBlockSize + m_bigBlockSize - m_buffers[0].size();
    vector<double> pad(n, 0.0);
    return process(pad);
}

vector<vector<double> >
ConstantQ::processOctaveBlock(int octave)
{
    vector<double> ro(m_p.fftSize, 0.0);
    vector<double> io(m_p.fftSize, 0.0);

    m_fft->forward(m_buffers[octave].data(), ro.data(), io.data());

    vector<double> shifted;
    shifted.insert(shifted.end(), 
                   m_buffers[octave].begin() + m_p.fftHop,
                   m_buffers[octave].end());
    m_buffers[octave] = shifted;

    vector<C> cv;
    for (int i = 0; i < m_p.fftSize; ++i) {
        cv.push_back(C(ro[i], io[i]));
    }

    vector<C> cqrowvec = m_kernel->process(cv);

    // Reform into a column matrix 
    vector<vector<double> > cqblock;
    for (int j = 0; j < m_p.atomsPerFrame; ++j) {
        cqblock.push_back(vector<double>());
        for (int i = 0; i < m_p.binsPerOctave; ++i) {
            cqblock[j].push_back(abs(cqrowvec[i * m_p.atomsPerFrame + j]));
        }
    }

    return cqblock;
}