annotate base/ColumnOp.h @ 1520:954d0cf29ca7 import-audio-data

Switch the normalisation option in WritableWaveFileModel from normalising on read to normalising on write, so that the saved file is already normalised and therefore can be read again without having to remember to normalise it

/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */

/*
    Sonic Visualiser
    An audio file viewer and annotation editor.
    Centre for Digital Music, Queen Mary, University of London.
    This file copyright 2006-2016 Chris Cannam and QMUL.
    
    This program is free software; you can redistribute it and/or
    modify it under the terms of the GNU General Public License as
    published by the Free Software Foundation; either version 2 of the
    License, or (at your option) any later version.  See the file
    COPYING included with this distribution for more information.
*/

#ifndef COLUMN_OP_H
#define COLUMN_OP_H

#include "BaseTypes.h"

#include <vector>

/**
 * Display normalization types for columns in e.g. grid plots.
 *
 * Max1 means to normalize to max value = 1.0.
 * Sum1 means to normalize to sum of values = 1.0.
 *
 * Range01 means to normalize such that the max value = 1.0 and the
 * min value (if different from the max value) = 0.0.
 *
 * Hybrid means normalize to max = 1.0 and then multiply by
 * log10 of the max value, to retain some difference between
 * levels of neighbouring columns.
 *
 * Area normalization is handled separately.
 */
enum class ColumnNormalization {
    None,
    Max1,
    Sum1,
    Range01,
    Hybrid
};

/**
 * Class containing static functions for simple operations on data
 * columns, for use by display layers.
 */
class ColumnOp
{
public:
    /** 
     * Column type. 
     */
    typedef std::vector<float> Column;

    /**
     * Scale the given column using the given gain multiplier.
     */
    static Column applyGain(const Column &in, double gain) {
        if (gain == 1.0) return in;
        Column out;
        out.reserve(in.size());
        for (auto v: in) out.push_back(float(v * gain));
        return out;
    }

    /**
     * Shift the values in the given column by the given offset.
     */
    static Column applyShift(const Column &in, float offset) {
        if (offset == 0.f) return in;
        Column out;
        out.reserve(in.size());
        for (auto v: in) out.push_back(v + offset);
        return out;
    }

    /**
     * Scale an FFT output downward by half the FFT size.
     */
    static Column fftScale(const Column &in, int fftSize);

    /**
     * Determine whether an index points to a local peak.
     */
    static bool isPeak(const Column &in, int ix) {
        if (!in_range_for(in, ix)) {
            return false;
        }
        if (ix == 0) {
            return in[0] >= in[1];
        }
        if (!in_range_for(in, ix+1)) {
            return in[ix] > in[ix-1];
        }
        if (in[ix] < in[ix+1]) {
            return false;
        }
        if (in[ix] <= in[ix-1]) {
            return false;
        }
        return true;
    }

    /**
     * Return a column containing only the local peak values (all
     * others zero).
     */
    static Column peakPick(const Column &in);

    /**
     * Return a column normalized from the input column according to
     * the given normalization scheme.
     *
     * Note that the sum or max (as appropriate) used for
     * normalisation will be calculated from the absolute values of
     * the column elements, should any of them be negative.
     */
    static Column normalize(const Column &in, ColumnNormalization n);
    
    /**
     * Distribute the given column into a target vector of a different
     * size, optionally using linear interpolation. The binfory vector
     * contains a mapping from y coordinate (i.e. index into the
     * target vector) to bin (i.e. index into the source column). The
     * source column ("in") may be a partial column; it's assumed to
     * contain enough bins to span the destination range, starting
     * with the bin of index minbin.
     */
    static Column distribute(const Column &in,
                             int h,
                             const std::vector<double> &binfory,
                             int minbin,
                             bool interpolate);

};

#endif