uk.co.modularaudio.util.audio.math.FirstDbToLevelComputer.java Source code

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Here is the source code for uk.co.modularaudio.util.audio.math.FirstDbToLevelComputer.java

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/**
 *
 * Copyright (C) 2015 - Daniel Hams, Modular Audio Limited
 *                      daniel.hams@gmail.com
 *
 * Mad 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 3 of the License, or
 * (at your option) any later version.
 *
 * Mad 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Mad.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

package uk.co.modularaudio.util.audio.math;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

@SuppressWarnings("unused")
public class FirstDbToLevelComputer implements DbToLevelComputer {
    public static final int LOWEST_NEGATIVE_DB = 50;
    public static final int MAX_OVERAMP_DB = 6;

    private static Log log = LogFactory.getLog(FirstDbToLevelComputer.class.getName());

    private int numTotalSteps = -1;
    private int numScaledSteps = -1;

    private float totalDynamicRange = 0.0f;

    private float upperRangeBound = 0.0f;

    private float dbPerStep = 0.0f;
    private float stepsPerDb = 0.0f;
    private float zeroDBLevel = 0.0f;

    public FirstDbToLevelComputer(int numTotalSteps) {
        // We assume a required DB range from:
        // -INF, -96DB -> 0 -> +9
        this.totalDynamicRange = LOWEST_NEGATIVE_DB + MAX_OVERAMP_DB;

        this.numTotalSteps = numTotalSteps;
        this.numScaledSteps = numTotalSteps - 1;

        // We will be running from 0 -> 1 in amplitude,
        // but will reserve the bottom step for -INF on the DB scale
        upperRangeBound = numScaledSteps / totalDynamicRange;

        dbPerStep = totalDynamicRange / numScaledSteps;
        stepsPerDb = 1.0f / dbPerStep;

        zeroDBLevel = numTotalSteps - (stepsPerDb * MAX_OVERAMP_DB);
    }

    public float toDbFromNormalisedLevel(float level) {
        // Slider is from 0 -> 1
        // special case 0
        if (level == 0.0f) {
            return Float.NEGATIVE_INFINITY;
        } else {
            return (level * totalDynamicRange) - LOWEST_NEGATIVE_DB;
        }
    }

    public float toNormalisedSliderLevelFromDb(float db) {
        if (db == Float.NEGATIVE_INFINITY) {
            return 0.0f;
        } else {
            return (db + LOWEST_NEGATIVE_DB) / totalDynamicRange;
        }
    }

}