/
mixer.c
1617 lines (1407 loc) · 44.5 KB
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/*
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SDL_mixer: An audio mixer library based on the SDL library
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Copyright (C) 1997-2019 Sam Lantinga <slouken@libsdl.org>
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This software is provided 'as-is', without any express or implied
warranty. In no event will the authors be held liable for any damages
arising from the use of this software.
Permission is granted to anyone to use this software for any purpose,
including commercial applications, and to alter it and redistribute it
freely, subject to the following restrictions:
1. The origin of this software must not be misrepresented; you must not
claim that you wrote the original software. If you use this software
in a product, an acknowledgment in the product documentation would be
appreciated but is not required.
2. Altered source versions must be plainly marked as such, and must not be
misrepresented as being the original software.
3. This notice may not be removed or altered from any source distribution.
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*/
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/* $Id$ */
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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
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#include "SDL.h"
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#include "SDL_mixer.h"
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#include "mixer.h"
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#include "music.h"
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#include "load_aiff.h"
#include "load_voc.h"
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#define MIX_INTERNAL_EFFECT__
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#include "effects_internal.h"
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/* Magic numbers for various audio file formats */
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#define RIFF 0x46464952 /* "RIFF" */
#define WAVE 0x45564157 /* "WAVE" */
#define FORM 0x4d524f46 /* "FORM" */
#define CREA 0x61657243 /* "Crea" */
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static int audio_opened = 0;
static SDL_AudioSpec mixer;
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static SDL_AudioDeviceID audio_device;
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typedef struct _Mix_effectinfo
{
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Mix_EffectFunc_t callback;
Mix_EffectDone_t done_callback;
void *udata;
struct _Mix_effectinfo *next;
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} effect_info;
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static struct _Mix_Channel {
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Mix_Chunk *chunk;
int playing;
int paused;
Uint8 *samples;
int volume;
int looping;
int tag;
Uint32 expire;
Uint32 start_time;
Mix_Fading fading;
int fade_volume;
int fade_volume_reset;
Uint32 fade_length;
Uint32 ticks_fade;
effect_info *effects;
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} *mix_channel = NULL;
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static effect_info *posteffects = NULL;
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static int num_channels;
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static int reserved_channels = 0;
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/* Support for hooking into the mixer callback system */
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static void (SDLCALL *mix_postmix)(void *udata, Uint8 *stream, int len) = NULL;
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static void *mix_postmix_data = NULL;
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/* rcg07062001 callback to alert when channels are done playing. */
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static void (SDLCALL *channel_done_callback)(int channel) = NULL;
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/* Support for user defined music functions */
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static void (SDLCALL *mix_music)(void *udata, Uint8 *stream, int len) = music_mixer;
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static void *music_data = NULL;
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/* rcg06042009 report available decoders at runtime. */
static const char **chunk_decoders = NULL;
static int num_decoders = 0;
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int Mix_GetNumChunkDecoders(void)
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{
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return(num_decoders);
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}
const char *Mix_GetChunkDecoder(int index)
{
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if ((index < 0) || (index >= num_decoders)) {
return NULL;
}
return(chunk_decoders[index]);
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}
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SDL_bool Mix_HasChunkDecoder(const char *name)
{
int index;
for (index = 0; index < num_decoders; ++index) {
if (SDL_strcasecmp(name, chunk_decoders[index]) == 0) {
return SDL_TRUE;
}
}
return SDL_FALSE;
}
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void add_chunk_decoder(const char *decoder)
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{
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int i;
void *ptr;
/* Check to see if we already have this decoder */
for (i = 0; i < num_decoders; ++i) {
if (SDL_strcmp(chunk_decoders[i], decoder) == 0) {
return;
}
}
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ptr = SDL_realloc((void *)chunk_decoders, (size_t)(num_decoders + 1) * sizeof (const char *));
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if (ptr == NULL) {
return; /* oh well, go on without it. */
}
chunk_decoders = (const char **) ptr;
chunk_decoders[num_decoders++] = decoder;
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}
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/* rcg06192001 get linked library's version. */
const SDL_version *Mix_Linked_Version(void)
{
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static SDL_version linked_version;
SDL_MIXER_VERSION(&linked_version);
return(&linked_version);
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}
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int Mix_Init(int flags)
{
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int result = 0;
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if (flags & MIX_INIT_FLAC) {
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if (load_music_type(MUS_FLAC)) {
open_music_type(MUS_FLAC);
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result |= MIX_INIT_FLAC;
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} else {
Mix_SetError("FLAC support not available");
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}
}
if (flags & MIX_INIT_MOD) {
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if (load_music_type(MUS_MOD)) {
open_music_type(MUS_MOD);
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result |= MIX_INIT_MOD;
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} else {
Mix_SetError("MOD support not available");
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}
}
if (flags & MIX_INIT_MP3) {
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if (load_music_type(MUS_MP3)) {
open_music_type(MUS_MP3);
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result |= MIX_INIT_MP3;
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} else {
Mix_SetError("MP3 support not available");
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}
}
if (flags & MIX_INIT_OGG) {
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if (load_music_type(MUS_OGG)) {
open_music_type(MUS_OGG);
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result |= MIX_INIT_OGG;
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} else {
Mix_SetError("OGG support not available");
}
}
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if (flags & MIX_INIT_OPUS) {
if (load_music_type(MUS_OPUS)) {
open_music_type(MUS_OPUS);
result |= MIX_INIT_OPUS;
} else {
Mix_SetError("OPUS support not available");
}
}
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if (flags & MIX_INIT_MID) {
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if (load_music_type(MUS_MID)) {
open_music_type(MUS_MID);
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result |= MIX_INIT_MID;
} else {
Mix_SetError("MIDI support not available");
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}
}
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return result;
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}
void Mix_Quit()
{
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unload_music();
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}
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static int _Mix_remove_all_effects(int channel, effect_info **e);
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/*
* rcg06122001 Cleanup effect callbacks.
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* MAKE SURE Mix_LockAudio() is called before this (or you're in the
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* audio callback).
*/
static void _Mix_channel_done_playing(int channel)
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{
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if (channel_done_callback) {
channel_done_callback(channel);
}
/*
* Call internal function directly, to avoid locking audio from
* inside audio callback.
*/
_Mix_remove_all_effects(channel, &mix_channel[channel].effects);
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}
static void *Mix_DoEffects(int chan, void *snd, int len)
{
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int posteffect = (chan == MIX_CHANNEL_POST);
effect_info *e = ((posteffect) ? posteffects : mix_channel[chan].effects);
void *buf = snd;
if (e != NULL) { /* are there any registered effects? */
/* if this is the postmix, we can just overwrite the original. */
if (!posteffect) {
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buf = SDL_malloc((size_t)len);
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if (buf == NULL) {
return(snd);
}
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SDL_memcpy(buf, snd, (size_t)len);
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}
for (; e != NULL; e = e->next) {
if (e->callback != NULL) {
e->callback(chan, buf, len, e->udata);
}
}
}
/* be sure to SDL_free() the return value if != snd ... */
return(buf);
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}
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/* Mixing function */
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static void SDLCALL
mix_channels(void *udata, Uint8 *stream, int len)
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{
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Uint8 *mix_input;
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int i, mixable, volume = MIX_MAX_VOLUME;
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Uint32 sdl_ticks;
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(void)udata;
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#if SDL_VERSION_ATLEAST(1, 3, 0)
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/* Need to initialize the stream in SDL 1.3+ */
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SDL_memset(stream, mixer.silence, (size_t)len);
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#endif
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/* Mix the music (must be done before the channels are added) */
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mix_music(music_data, stream, len);
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/* Mix any playing channels... */
sdl_ticks = SDL_GetTicks();
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for (i=0; i<num_channels; ++i) {
if (!mix_channel[i].paused) {
if (mix_channel[i].expire > 0 && mix_channel[i].expire < sdl_ticks) {
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/* Expiration delay for that channel is reached */
mix_channel[i].playing = 0;
mix_channel[i].looping = 0;
mix_channel[i].fading = MIX_NO_FADING;
mix_channel[i].expire = 0;
_Mix_channel_done_playing(i);
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} else if (mix_channel[i].fading != MIX_NO_FADING) {
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Uint32 ticks = sdl_ticks - mix_channel[i].ticks_fade;
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if (ticks >= mix_channel[i].fade_length) {
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Mix_Volume(i, mix_channel[i].fade_volume_reset); /* Restore the volume */
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if(mix_channel[i].fading == MIX_FADING_OUT) {
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mix_channel[i].playing = 0;
mix_channel[i].looping = 0;
mix_channel[i].expire = 0;
_Mix_channel_done_playing(i);
}
mix_channel[i].fading = MIX_NO_FADING;
} else {
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if (mix_channel[i].fading == MIX_FADING_OUT) {
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Mix_Volume(i, (mix_channel[i].fade_volume * (mix_channel[i].fade_length-ticks))
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/ mix_channel[i].fade_length);
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} else {
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Mix_Volume(i, (mix_channel[i].fade_volume * ticks) / mix_channel[i].fade_length);
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}
}
}
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if (mix_channel[i].playing > 0) {
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int index = 0;
int remaining = len;
while (mix_channel[i].playing > 0 && index < len) {
remaining = len - index;
volume = (mix_channel[i].volume*mix_channel[i].chunk->volume) / MIX_MAX_VOLUME;
mixable = mix_channel[i].playing;
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if (mixable > remaining) {
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mixable = remaining;
}
mix_input = Mix_DoEffects(i, mix_channel[i].samples, mixable);
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SDL_MixAudioFormat(stream+index,mix_input,mixer.format,mixable,volume);
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if (mix_input != mix_channel[i].samples)
SDL_free(mix_input);
mix_channel[i].samples += mixable;
mix_channel[i].playing -= mixable;
index += mixable;
/* rcg06072001 Alert app if channel is done playing. */
if (!mix_channel[i].playing && !mix_channel[i].looping) {
_Mix_channel_done_playing(i);
}
}
/* If looping the sample and we are at its end, make sure
we will still return a full buffer */
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while (mix_channel[i].looping && index < len) {
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int alen = mix_channel[i].chunk->alen;
remaining = len - index;
if (remaining > alen) {
remaining = alen;
}
mix_input = Mix_DoEffects(i, mix_channel[i].chunk->abuf, remaining);
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SDL_MixAudioFormat(stream+index, mix_input, mixer.format, remaining, volume);
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if (mix_input != mix_channel[i].chunk->abuf)
SDL_free(mix_input);
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if (mix_channel[i].looping > 0) {
--mix_channel[i].looping;
}
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mix_channel[i].samples = mix_channel[i].chunk->abuf + remaining;
mix_channel[i].playing = mix_channel[i].chunk->alen - remaining;
index += remaining;
}
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if (! mix_channel[i].playing && mix_channel[i].looping) {
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if (mix_channel[i].looping > 0) {
--mix_channel[i].looping;
}
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mix_channel[i].samples = mix_channel[i].chunk->abuf;
mix_channel[i].playing = mix_channel[i].chunk->alen;
}
}
}
}
/* rcg06122001 run posteffects... */
Mix_DoEffects(MIX_CHANNEL_POST, stream, len);
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if (mix_postmix) {
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mix_postmix(mix_postmix_data, stream, len);
}
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}
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#if 0
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static void PrintFormat(char *title, SDL_AudioSpec *fmt)
{
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printf("%s: %d bit %s audio (%s) at %u Hz\n", title, (fmt->format&0xFF),
(fmt->format&0x8000) ? "signed" : "unsigned",
(fmt->channels > 2) ? "surround" :
(fmt->channels > 1) ? "stereo" : "mono", fmt->freq);
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}
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#endif
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/* Open the mixer with a certain desired audio format */
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int Mix_OpenAudioDevice(int frequency, Uint16 format, int nchannels, int chunksize,
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const char* device, int allowed_changes)
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{
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int i;
SDL_AudioSpec desired;
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/* This used to call SDL_OpenAudio(), which initializes the audio
subsystem if necessary. Since SDL_OpenAudioDevice() doesn't,
we have to handle this case here. */
if (!SDL_WasInit(SDL_INIT_AUDIO)) {
if (SDL_InitSubSystem(SDL_INIT_AUDIO) < 0) {
return -1;
}
}
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/* If the mixer is already opened, increment open count */
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if (audio_opened) {
if (format == mixer.format && nchannels == mixer.channels) {
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++audio_opened;
return(0);
}
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while (audio_opened) {
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Mix_CloseAudio();
}
}
/* Set the desired format and frequency */
desired.freq = frequency;
desired.format = format;
desired.channels = nchannels;
desired.samples = chunksize;
desired.callback = mix_channels;
desired.userdata = NULL;
/* Accept nearly any audio format */
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if ((audio_device = SDL_OpenAudioDevice(device, 0, &desired, &mixer, allowed_changes)) == 0) {
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return(-1);
}
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#if 0
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PrintFormat("Audio device", &mixer);
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#endif
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num_channels = MIX_CHANNELS;
mix_channel = (struct _Mix_Channel *) SDL_malloc(num_channels * sizeof(struct _Mix_Channel));
/* Clear out the audio channels */
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for (i=0; i<num_channels; ++i) {
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mix_channel[i].chunk = NULL;
mix_channel[i].playing = 0;
mix_channel[i].looping = 0;
mix_channel[i].volume = SDL_MIX_MAXVOLUME;
mix_channel[i].fade_volume = SDL_MIX_MAXVOLUME;
mix_channel[i].fade_volume_reset = SDL_MIX_MAXVOLUME;
mix_channel[i].fading = MIX_NO_FADING;
mix_channel[i].tag = -1;
mix_channel[i].expire = 0;
mix_channel[i].effects = NULL;
mix_channel[i].paused = 0;
}
Mix_VolumeMusic(SDL_MIX_MAXVOLUME);
_Mix_InitEffects();
add_chunk_decoder("WAVE");
add_chunk_decoder("AIFF");
add_chunk_decoder("VOC");
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/* Initialize the music players */
open_music(&mixer);
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audio_opened = 1;
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SDL_PauseAudioDevice(audio_device, 0);
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return(0);
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}
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/* Open the mixer with a certain desired audio format */
int Mix_OpenAudio(int frequency, Uint16 format, int nchannels, int chunksize)
{
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return Mix_OpenAudioDevice(frequency, format, nchannels, chunksize, NULL,
SDL_AUDIO_ALLOW_FREQUENCY_CHANGE |
SDL_AUDIO_ALLOW_CHANNELS_CHANGE);
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}
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/* Dynamically change the number of channels managed by the mixer.
If decreasing the number of channels, the upper channels are
stopped.
*/
int Mix_AllocateChannels(int numchans)
{
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if (numchans<0 || numchans==num_channels)
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return(num_channels);
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if (numchans < num_channels) {
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/* Stop the affected channels */
int i;
for(i=numchans; i < num_channels; i++) {
Mix_UnregisterAllEffects(i);
Mix_HaltChannel(i);
}
}
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Mix_LockAudio();
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mix_channel = (struct _Mix_Channel *) SDL_realloc(mix_channel, numchans * sizeof(struct _Mix_Channel));
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if (numchans > num_channels) {
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/* Initialize the new channels */
int i;
for(i=num_channels; i < numchans; i++) {
mix_channel[i].chunk = NULL;
mix_channel[i].playing = 0;
mix_channel[i].looping = 0;
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mix_channel[i].volume = MIX_MAX_VOLUME;
mix_channel[i].fade_volume = MIX_MAX_VOLUME;
mix_channel[i].fade_volume_reset = MIX_MAX_VOLUME;
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mix_channel[i].fading = MIX_NO_FADING;
mix_channel[i].tag = -1;
mix_channel[i].expire = 0;
mix_channel[i].effects = NULL;
mix_channel[i].paused = 0;
}
}
num_channels = numchans;
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Mix_UnlockAudio();
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return(num_channels);
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}
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/* Return the actual mixer parameters */
int Mix_QuerySpec(int *frequency, Uint16 *format, int *channels)
{
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if (audio_opened) {
if (frequency) {
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*frequency = mixer.freq;
}
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if (format) {
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*format = mixer.format;
}
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if (channels) {
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*channels = mixer.channels;
}
}
return(audio_opened);
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}
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typedef struct _MusicFragment
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{
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Uint8 *data;
int size;
struct _MusicFragment *next;
} MusicFragment;
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static SDL_AudioSpec *Mix_LoadMusic_RW(SDL_RWops *src, int freesrc, SDL_AudioSpec *spec, Uint8 **audio_buf, Uint32 *audio_len)
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{
int i;
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Mix_MusicType music_type;
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Mix_MusicInterface *interface = NULL;
void *music = NULL;
Sint64 start;
SDL_bool playing;
MusicFragment *first = NULL, *last = NULL, *fragment = NULL;
int count = 0;
int fragment_size;
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music_type = detect_music_type(src);
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if (!load_music_type(music_type) || !open_music_type(music_type)) {
return NULL;
}
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*spec = mixer;
/* Use fragments sized on full audio frame boundaries - this'll do */
fragment_size = spec->size;
start = SDL_RWtell(src);
for (i = 0; i < get_num_music_interfaces(); ++i) {
interface = get_music_interface(i);
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if (!interface->opened) {
continue;
}
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if (interface->type != music_type) {
continue;
}
if (!interface->CreateFromRW || !interface->GetAudio) {
continue;
}
/* These music interfaces are not safe to use while music is playing */
if (interface->api == MIX_MUSIC_CMD ||
interface->api == MIX_MUSIC_MIKMOD ||
interface->api == MIX_MUSIC_NATIVEMIDI) {
continue;
}
music = interface->CreateFromRW(src, freesrc);
if (music) {
/* The interface owns the data source now */
freesrc = SDL_FALSE;
break;
}
/* Reset the stream for the next decoder */
SDL_RWseek(src, start, RW_SEEK_SET);
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}
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if (!music) {
if (freesrc) {
SDL_RWclose(src);
}
Mix_SetError("Unrecognized audio format");
return NULL;
}
Mix_LockAudio();
if (interface->Play) {
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interface->Play(music, 1);
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}
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playing = SDL_TRUE;
while (playing) {
int left;
fragment = (MusicFragment *)SDL_malloc(sizeof(*fragment));
if (!fragment) {
/* Uh oh, out of memory, let's return what we have */
break;
}
fragment->data = (Uint8 *)SDL_malloc(fragment_size);
if (!fragment->data) {
/* Uh oh, out of memory, let's return what we have */
SDL_free(fragment);
break;
}
fragment->next = NULL;
left = interface->GetAudio(music, fragment->data, fragment_size);
if (left > 0) {
playing = SDL_FALSE;
} else if (interface->IsPlaying) {
playing = interface->IsPlaying(music);
}
fragment->size = (fragment_size - left);
if (!first) {
first = fragment;
}
if (last) {
last->next = fragment;
}
last = fragment;
++count;
}
if (interface->Stop) {
interface->Stop(music);
}
if (music) {
interface->Delete(music);
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}
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Mix_UnlockAudio();
if (count > 0) {
*audio_len = (count - 1) * fragment_size + fragment->size;
*audio_buf = (Uint8 *)SDL_malloc(*audio_len);
if (*audio_buf) {
Uint8 *dst = *audio_buf;
for (fragment = first; fragment; fragment = fragment->next) {
SDL_memcpy(dst, fragment->data, fragment->size);
dst += fragment->size;
}
} else {
SDL_OutOfMemory();
spec = NULL;
}
} else {
Mix_SetError("No audio data");
spec = NULL;
}
while (first) {
fragment = first;
first = first->next;
SDL_free(fragment->data);
SDL_free(fragment);
}
if (freesrc) {
SDL_RWclose(src);
}
return spec;
673
}
674
675
676
677
/* Load a wave file */
Mix_Chunk *Mix_LoadWAV_RW(SDL_RWops *src, int freesrc)
{
678
Uint8 magic[4];
679
680
681
682
683
684
Mix_Chunk *chunk;
SDL_AudioSpec wavespec, *loaded;
SDL_AudioCVT wavecvt;
int samplesize;
/* rcg06012001 Make sure src is valid */
685
if (!src) {
686
687
688
689
690
SDL_SetError("Mix_LoadWAV_RW with NULL src");
return(NULL);
}
/* Make sure audio has been opened */
691
if (!audio_opened) {
692
SDL_SetError("Audio device hasn't been opened");
693
if (freesrc) {
694
695
696
697
698
699
700
SDL_RWclose(src);
}
return(NULL);
}
/* Allocate the chunk memory */
chunk = (Mix_Chunk *)SDL_malloc(sizeof(Mix_Chunk));
701
if (chunk == NULL) {
702
SDL_SetError("Out of memory");
703
if (freesrc) {
704
705
706
707
708
709
SDL_RWclose(src);
}
return(NULL);
}
/* Find out what kind of audio file this is */
710
711
712
713
714
715
716
if (SDL_RWread(src, magic, 1, 4) != 4) {
if (freesrc) {
SDL_RWclose(src);
}
Mix_SetError("Couldn't read first 4 bytes of audio data");
return NULL;
}
717
/* Seek backwards for compatibility with older loaders */
718
719
720
721
722
723
SDL_RWseek(src, -4, RW_SEEK_CUR);
if (SDL_memcmp(magic, "WAVE", 4) == 0 || SDL_memcmp(magic, "RIFF", 4) == 0) {
loaded = SDL_LoadWAV_RW(src, freesrc, &wavespec, (Uint8 **)&chunk->abuf, &chunk->alen);
} else if (SDL_memcmp(magic, "FORM", 4) == 0) {
loaded = Mix_LoadAIFF_RW(src, freesrc, &wavespec, (Uint8 **)&chunk->abuf, &chunk->alen);
724
} else if (SDL_memcmp(magic, "Crea", 4) == 0) {
725
726
loaded = Mix_LoadVOC_RW(src, freesrc, &wavespec, (Uint8 **)&chunk->abuf, &chunk->alen);
} else {
727
loaded = Mix_LoadMusic_RW(src, freesrc, &wavespec, (Uint8 **)&chunk->abuf, &chunk->alen);
728
}
729
if (!loaded) {
730
731
732
733
/* The individual loaders have closed src if needed */
SDL_free(chunk);
return(NULL);
}
734
735
#if 0
736
737
PrintFormat("Audio device", &mixer);
PrintFormat("-- Wave file", &wavespec);
738
739
#endif
740
/* Build the audio converter and create conversion buffers */
741
if (wavespec.format != mixer.format ||
742
wavespec.channels != mixer.channels ||
743
744
wavespec.freq != mixer.freq) {
if (SDL_BuildAudioCVT(&wavecvt,
745
wavespec.format, wavespec.channels, wavespec.freq,
746
mixer.format, mixer.channels, mixer.freq) < 0) {
747
748
749
750
751
752
753
SDL_free(chunk->abuf);
SDL_free(chunk);
return(NULL);
}
samplesize = ((wavespec.format & 0xFF)/8)*wavespec.channels;
wavecvt.len = chunk->alen & ~(samplesize-1);
wavecvt.buf = (Uint8 *)SDL_calloc(1, wavecvt.len*wavecvt.len_mult);
754
if (wavecvt.buf == NULL) {
755
756
757
758
759
SDL_SetError("Out of memory");
SDL_free(chunk->abuf);
SDL_free(chunk);
return(NULL);
}
760
SDL_memcpy(wavecvt.buf, chunk->abuf, wavecvt.len);
761
762
763
SDL_free(chunk->abuf);
/* Run the audio converter */
764
if (SDL_ConvertAudio(&wavecvt) < 0) {
765
766
767
768
769
770
771
772
773
774
775
776
777
SDL_free(wavecvt.buf);
SDL_free(chunk);
return(NULL);
}
chunk->abuf = wavecvt.buf;
chunk->alen = wavecvt.len_cvt;
}
chunk->allocated = 1;
chunk->volume = MIX_MAX_VOLUME;
return(chunk);
778
779
}
780
781
782
/* Load a wave file of the mixer format from a memory buffer */
Mix_Chunk *Mix_QuickLoad_WAV(Uint8 *mem)
{
783
784
785
786
Mix_Chunk *chunk;
Uint8 magic[4];
/* Make sure audio has been opened */
787
if (! audio_opened) {
788
789
790
791
792
793
SDL_SetError("Audio device hasn't been opened");
return(NULL);
}
/* Allocate the chunk memory */
chunk = (Mix_Chunk *)SDL_calloc(1,sizeof(Mix_Chunk));
794
if (chunk == NULL) {
795
796
797
798
799
800
801
802
SDL_SetError("Out of memory");
return(NULL);
}
/* Essentially just skip to the audio data (no error checking - fast) */
chunk->allocated = 0;
mem += 12; /* WAV header */
do {
803
SDL_memcpy(magic, mem, 4);
804
805
806
807
808
mem += 4;
chunk->alen = ((mem[3]<<24)|(mem[2]<<16)|(mem[1]<<8)|(mem[0]));
mem += 4;
chunk->abuf = mem;
mem += chunk->alen;
809
} while (memcmp(magic, "data", 4) != 0);
810
811
812
chunk->volume = MIX_MAX_VOLUME;
return(chunk);
813
814
}
815
816
817
/* Load raw audio data of the mixer format from a memory buffer */
Mix_Chunk *Mix_QuickLoad_RAW(Uint8 *mem, Uint32 len)
{
818
819
820
Mix_Chunk *chunk;
/* Make sure audio has been opened */
821
if (! audio_opened) {
822
823
824
825
826
827
SDL_SetError("Audio device hasn't been opened");
return(NULL);
}
/* Allocate the chunk memory */
chunk = (Mix_Chunk *)SDL_malloc(sizeof(Mix_Chunk));
828
if (chunk == NULL) {
829
830
831
832
833
834
835
836
837
838
839
SDL_SetError("Out of memory");
return(NULL);
}
/* Essentially just point at the audio data (no error checking - fast) */
chunk->allocated = 0;
chunk->alen = len;
chunk->abuf = mem;
chunk->volume = MIX_MAX_VOLUME;
return(chunk);
840
841
}
842
843
844
/* Free an audio chunk previously loaded */
void Mix_FreeChunk(Mix_Chunk *chunk)
{
845
846
847
int i;
/* Caution -- if the chunk is playing, the mixer will crash */
848
if (chunk) {
849
/* Guarantee that this chunk isn't playing */
850
Mix_LockAudio();
851
852
853
if (mix_channel) {
for (i=0; i<num_channels; ++i) {
if (chunk == mix_channel[i].chunk) {
854
855
856
857
858
mix_channel[i].playing = 0;
mix_channel[i].looping = 0;
}
}
}
859
Mix_UnlockAudio();
860
/* Actually free the chunk */
861
if (chunk->allocated) {
862
863
864
865
SDL_free(chunk->abuf);
}
SDL_free(chunk);
}
866
867
}
868
869
870
871
/* Set a function that is called after all mixing is performed.
This can be used to provide real-time visual display of the audio stream
or add a custom mixer filter for the stream data.
*/
872
void Mix_SetPostMix(void (SDLCALL *mix_func)
873
874
(void *udata, Uint8 *stream, int len), void *arg)
{
875
Mix_LockAudio();
876
877
mix_postmix_data = arg;
mix_postmix = mix_func;
878
Mix_UnlockAudio();
879
880
}
881
882
883
/* Add your own music player or mixer function.
If 'mix_func' is NULL, the default music player is re-enabled.
*/
884
void Mix_HookMusic(void (SDLCALL *mix_func)(void *udata, Uint8 *stream, int len),
885
886
void *arg)
{
887
Mix_LockAudio();
888
if (mix_func != NULL) {
889
890
891
892
893
894
music_data = arg;
mix_music = mix_func;
} else {
music_data = NULL;
mix_music = music_mixer;
}
895
Mix_UnlockAudio();
896
897
898
899
}
void *Mix_GetMusicHookData(void)
{
900
return(music_data);
901
902
}
903
void Mix_ChannelFinished(void (SDLCALL *channel_finished)(int channel))
904
{
905
Mix_LockAudio();
906
channel_done_callback = channel_finished;
907
Mix_UnlockAudio();
908
909
910
}
911
912
913
914
915
916
/* Reserve the first channels (0 -> n-1) for the application, i.e. don't allocate
them dynamically to the next sample if requested with a -1 value below.
Returns the number of reserved channels.
*/
int Mix_ReserveChannels(int num)
{
917
918
919
920
if (num > num_channels)
num = num_channels;
reserved_channels = num;
return num;
921
922
}
923
924
static int checkchunkintegral(Mix_Chunk *chunk)
{
925
int frame_width = 1;
926
927
928
929
930
if ((mixer.format & 0xFF) == 16) frame_width = 2;
frame_width *= mixer.channels;
while (chunk->alen % frame_width) chunk->alen--;
return chunk->alen;
931
932
}
933
934
/* Play an audio chunk on a specific channel.
If the specified channel is -1, play on the first free channel.
935
936
'ticks' is the number of milliseconds at most to play the sample, or -1
if there is no limit.
937
938
Returns which channel was used to play the sound.
*/
939
int Mix_PlayChannelTimed(int which, Mix_Chunk *chunk, int loops, int ticks)
940
{
941
942
943
int i;
/* Don't play null pointers :-) */
944
if (chunk == NULL) {
945
946
947
Mix_SetError("Tried to play a NULL chunk");
return(-1);
}
948
if (!checkchunkintegral(chunk)) {
949
950
951
952
953
Mix_SetError("Tried to play a chunk with a bad frame");
return(-1);
}
/* Lock the mixer while modifying the playing channels */
954
Mix_LockAudio();
955
956
{
/* If which is -1, play on the first free channel */
957
958
959
if (which == -1) {
for (i=reserved_channels; i<num_channels; ++i) {
if (mix_channel[i].playing <= 0)
960
961
break;
}
962
if (i == num_channels) {
963
964
965
966
967
968
969
970
Mix_SetError("No free channels available");
which = -1;
} else {
which = i;
}
}
/* Queue up the audio data for this channel */
971
if (which >= 0 && which < num_channels) {
972
973
974
975
Uint32 sdl_ticks = SDL_GetTicks();
if (Mix_Playing(which))
_Mix_channel_done_playing(which);
mix_channel[which].samples = chunk->abuf;
976
mix_channel[which].playing = (int)chunk->alen;
977
978
979
980
981
mix_channel[which].looping = loops;
mix_channel[which].chunk = chunk;
mix_channel[which].paused = 0;
mix_channel[which].fading = MIX_NO_FADING;
mix_channel[which].start_time = sdl_ticks;
982
mix_channel[which].expire = (ticks > 0) ? (sdl_ticks + (Uint32)ticks) : 0;
983
984
}
}
985
Mix_UnlockAudio();
986
987
988
/* Return the channel on which the sound is being played */
return(which);
989
990
}
991
992
993
/* Change the expiration delay for a channel */
int Mix_ExpireChannel(int which, int ticks)
{
994
995
int status = 0;
996
if (which == -1) {
997
int i;
998
for (i=0; i < num_channels; ++ i) {
999
1000
status += Mix_ExpireChannel(i, ticks);
}