forked from KolibriOS/kolibrios
cb09ffbbd3
OGG, AIFF and VOC only support. git-svn-id: svn://kolibrios.org@9565 a494cfbc-eb01-0410-851d-a64ba20cac60
125 lines
3.3 KiB
C
125 lines
3.3 KiB
C
/*
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SDL_mixer: An audio mixer library based on the SDL library
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Copyright (C) 1997-2012 Sam Lantinga <slouken@libsdl.org>
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This software is provided 'as-is', without any express or implied
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warranty. In no event will the authors be held liable for any damages
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arising from the use of this software.
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Permission is granted to anyone to use this software for any purpose,
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including commercial applications, and to alter it and redistribute it
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freely, subject to the following restrictions:
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1. The origin of this software must not be misrepresented; you must not
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claim that you wrote the original software. If you use this software
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in a product, an acknowledgment in the product documentation would be
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appreciated but is not required.
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2. Altered source versions must be plainly marked as such, and must not be
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misrepresented as being the original software.
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3. This notice may not be removed or altered from any source distribution.
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This file by Ryan C. Gordon (icculus@icculus.org)
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These are some helper functions for the internal mixer special effects.
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*/
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/* $Id$ */
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/* ------ These are used internally only. Don't touch. ------ */
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#include <stdio.h>
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#include <stdlib.h>
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#include "SDL_mixer.h"
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#define __MIX_INTERNAL_EFFECT__
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#include "effects_internal.h"
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/* Should we favor speed over memory usage and/or quality of output? */
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int _Mix_effects_max_speed = 0;
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void _Mix_InitEffects(void)
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{
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_Mix_effects_max_speed = (SDL_getenv(MIX_EFFECTSMAXSPEED) != NULL);
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}
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void _Mix_DeinitEffects(void)
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{
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_Eff_PositionDeinit();
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}
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void *_Eff_volume_table = NULL;
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/* Build the volume table for Uint8-format samples.
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*
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* Each column of the table is a possible sample, while each row of the
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* table is a volume. Volume is a Uint8, where 0 is silence and 255 is full
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* volume. So _Eff_volume_table[128][mysample] would be the value of
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* mysample, at half volume.
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*/
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void *_Eff_build_volume_table_u8(void)
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{
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int volume;
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int sample;
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Uint8 *rc;
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if (!_Mix_effects_max_speed) {
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return(NULL);
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}
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if (!_Eff_volume_table) {
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rc = SDL_malloc(256 * 256);
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if (rc) {
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_Eff_volume_table = (void *) rc;
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for (volume = 0; volume < 256; volume++) {
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for (sample = -128; sample < 128; sample ++) {
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*rc = (Uint8)(((float) sample) * ((float) volume / 255.0))
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+ 128;
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rc++;
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}
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}
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}
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}
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return(_Eff_volume_table);
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}
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/* Build the volume table for Sint8-format samples.
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*
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* Each column of the table is a possible sample, while each row of the
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* table is a volume. Volume is a Uint8, where 0 is silence and 255 is full
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* volume. So _Eff_volume_table[128][mysample+128] would be the value of
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* mysample, at half volume.
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*/
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void *_Eff_build_volume_table_s8(void)
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{
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int volume;
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int sample;
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Sint8 *rc;
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if (!_Eff_volume_table) {
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rc = SDL_malloc(256 * 256);
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if (rc) {
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_Eff_volume_table = (void *) rc;
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for (volume = 0; volume < 256; volume++) {
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for (sample = -128; sample < 128; sample ++) {
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*rc = (Sint8)(((float) sample) * ((float) volume / 255.0));
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rc++;
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}
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}
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}
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}
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return(_Eff_volume_table);
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}
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/* end of effects.c ... */
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