/*
 * Copyright (C) 2018-2020 Alexandros Theodotou <alex at zrythm dot org>
 *
 * This file is part of Zrythm
 *
 * Zrythm is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Zrythm 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with Zrythm.  If not, see <https://www.gnu.org/licenses/>.
 */

#ifndef __AUDIO_PAN_H__
#define __AUDIO_PAN_H__

/** The amplitude of -3dBfs (0.707945784f). */
#define PAN_MINUS_3DB_AMP (- 0.292054216f)

/** The amplitude of -6dBfs (0.501187234f). */
#define PAN_MINUS_6DB_AMP (- 0.498812766f)

/**
 * \file
 *
 * Panning mono sources.
 */

/**
 * These are only useful when changing mono to
 * stereo.
 *
 * No compensation is needed for stereo to stereo.
 * See https://www.hackaudio.com/digital-signal-processing/stereo-audio/square-law-panning/
 */
typedef enum PanLaw
{
  PAN_LAW_0DB,
  PAN_LAW_MINUS_3DB,
  PAN_LAW_MINUS_6DB
} PanLaw;

static const char * pan_law_str[] =
{
  /* TRANSLATORS: decibels */
  __("0dB"),
  __("-3dB"),
  __("-6dB"),
};

static inline const char *
pan_law_to_string (
  PanLaw pan_law)
{
  return pan_law_str[pan_law];
}

/**
 * See https://www.harmonycentral.com/articles/the-truth-about-panning-laws
 */
typedef enum PanAlgorithm
{
  PAN_ALGORITHM_LINEAR,
  PAN_ALGORITHM_SQUARE_ROOT,
  PAN_ALGORITHM_SINE_LAW
} PanAlgorithm;

static const char * pan_algorithm_str[] =
{
  __("Linear"),
  __("Square Root"),
  __("Sine"),
};

static inline const char *
pan_algorithm_to_string (
  PanAlgorithm pan_algo)
{
  return pan_algorithm_str[pan_algo];
}

void
pan_get_calc_lr (
  PanLaw       law,
  PanAlgorithm algo,
  float        pan,
  float *      calc_l,
  float *      calc_r);

#endif
