music.c

SDL_mixer 是一个基于 SDL 的混音器

/*
    SDL_mixer:  An audio mixer library based on the SDL library
    Copyright (C) 1997-2004 Sam Lantinga

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
    License as published by the Free Software Foundation; either
    version 2 of the License, or (at your option) any later version.

    This library 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
    Library General Public License for more details.

    You should have received a copy of the GNU Library General Public
    License along with this library; if not, write to the Free
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

    Sam Lantinga
    [e-mail]
*/

/* $Id: music.c 2408 2006-05-12 09:42:24Z slouken $ */

#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <assert.h>
#include "SDL_endian.h"
#include "SDL_audio.h"
#include "SDL_timer.h"

#include "SDL_mixer.h"

#define SDL_SURROUND

#ifdef SDL_SURROUND
#define MAX_OUTPUT_CHANNELS 6
#else
#define MAX_OUTPUT_CHANNELS 2
#endif

/* The music command hack is UNIX specific */
#ifndef unix
#undef CMD_MUSIC
#endif

#ifdef CMD_MUSIC
#include "music_cmd.h"
#endif
#ifdef WAV_MUSIC
#include "wavestream.h"
#endif
#if defined(MOD_MUSIC) || defined(LIBMIKMOD_MUSIC)
#  include "mikmod.h"
#  if defined(LIBMIKMOD_VERSION)                /* libmikmod 3.1.8 */
#    define UNIMOD			MODULE
#    define MikMod_Init()		MikMod_Init(NULL)
#    define MikMod_LoadSong(a,b)	Player_Load(a,b,0)
#    ifndef LIBMIKMOD_MUSIC
#    define MikMod_LoadSongRW(a,b)	Player_LoadRW(a,b,0)
#    endif
#    define MikMod_FreeSong		Player_Free
     extern int MikMod_errno;
#  else                                        /* old MikMod 3.0.3 */
#    define MikMod_strerror(x)		_mm_errmsg[x])
#    define MikMod_errno		_mm_errno
#  endif
#endif
#ifdef MID_MUSIC
#  ifdef USE_TIMIDITY_MIDI
#    include "timidity.h"
#  endif
#  ifdef USE_NATIVE_MIDI
#    include "native_midi.h"
#  endif
#  if defined(USE_TIMIDITY_MIDI) && defined(USE_NATIVE_MIDI)
#    define MIDI_ELSE	else
#  else
#    define MIDI_ELSE
#  endif
#endif
#ifdef OGG_MUSIC
#include "music_ogg.h"
#endif
#ifdef MP3_MUSIC
#include "dynamic_mp3.h"

static SDL_AudioSpec used_mixer;
#endif

int volatile music_active = 1;
static int volatile music_stopped = 0;
static int music_loops = 0;
static char *music_cmd = NULL;
static Mix_Music * volatile music_playing = NULL;
static int music_volume = MIX_MAX_VOLUME;
static int music_swap8;
static int music_swap16;

struct _Mix_Music {
	Mix_MusicType type;
	union {
#ifdef CMD_MUSIC
		MusicCMD *cmd;
#endif
#ifdef WAV_MUSIC
		WAVStream *wave;
#endif
#if defined(MOD_MUSIC) || defined(LIBMIKMOD_MUSIC)
		UNIMOD *module;
#endif
#ifdef MID_MUSIC
#ifdef USE_TIMIDITY_MIDI
		MidiSong *midi;
#endif
#ifdef USE_NATIVE_MIDI
		NativeMidiSong *nativemidi;
#endif
#endif
#ifdef OGG_MUSIC
		OGG_music *ogg;
#endif
#ifdef MP3_MUSIC
		SMPEG *mp3;
#endif
	} data;
	Mix_Fading fading;
	int fade_step;
	int fade_steps;
	int error;
};
#ifdef MID_MUSIC
#ifdef USE_TIMIDITY_MIDI
static int timidity_ok;
static int samplesize;
#endif
#ifdef USE_NATIVE_MIDI
static int native_midi_ok;
#endif
#endif

/* Reference for converting mikmod output to 4/6 channels */
static int current_output_channels;
static Uint16 current_output_format;

/* Used to calculate fading steps */
static int ms_per_step;

/* Local low-level functions prototypes */
static void music_internal_initialize_volume(void);
static void music_internal_volume(int volume);
static int  music_internal_play(Mix_Music *music, double position);
static int  music_internal_position(double position);
static int  music_internal_playing();
static void music_internal_halt(void);


/* Support for hooking when the music has finished */
static void (*music_finished_hook)(void) = NULL;

void Mix_HookMusicFinished(void (*music_finished)(void))
{
	SDL_LockAudio();
	music_finished_hook = music_finished;
	SDL_UnlockAudio();
}


/* If music isn't playing, halt it if no looping is required, restart it */
/* otherwhise. NOP if the music is playing */
static int music_halt_or_loop (void)
{
	/* Restart music if it has to loop */
	
	if (!music_internal_playing()) 
	{
		/* Restart music if it has to loop at a high level */
		if (music_loops && --music_loops)
		{
			Mix_Fading current_fade = music_playing->fading;
			music_internal_play(music_playing, 0.0);
			music_playing->fading = current_fade;
		} 
		else 
		{
			music_internal_halt();
			if (music_finished_hook)
				music_finished_hook();
			
			return 0;
		}
	}
	
	return 1;
}



/* Mixing function */
void music_mixer(void *udata, Uint8 *stream, int len)
{
	if ( music_playing && music_active ) {
		/* Handle fading */
		if ( music_playing->fading != MIX_NO_FADING ) {
			if ( music_playing->fade_step++ < music_playing->fade_steps ) {
				int volume;
				int fade_step = music_playing->fade_step;
				int fade_steps = music_playing->fade_steps;

				if ( music_playing->fading == MIX_FADING_OUT ) {
					volume = (music_volume * (fade_steps-fade_step)) / fade_steps;
				} else { /* Fading in */
					volume = (music_volume * fade_step) / fade_steps;
				}
				music_internal_volume(volume);
			} else {
				if ( music_playing->fading == MIX_FADING_OUT ) {
					music_internal_halt();
					if ( music_finished_hook ) {
						music_finished_hook();
					}
					return;
				}
				music_playing->fading = MIX_NO_FADING;
			}
		}
		
		if (music_halt_or_loop() == 0)
			return;
		
		
		switch (music_playing->type) {
#ifdef CMD_MUSIC
			case MUS_CMD:
				/* The playing is done externally */
				break;
#endif
#ifdef WAV_MUSIC
			case MUS_WAV:
				WAVStream_PlaySome(stream, len);
				break;
#endif
#if defined(MOD_MUSIC) || defined(LIBMIKMOD_MUSIC)
			case MUS_MOD:
				if (current_output_channels > 2) {
					int small_len = 2 * len / current_output_channels;
					int i;
					Uint8 *src, *dst;

					VC_WriteBytes((SBYTE *)stream, small_len);
					/* and extend to len by copying channels */
					src = stream + small_len;
					dst = stream + len;

					switch (current_output_format & 0xFF) {
						case 8:
							for ( i=small_len/2; i; --i ) {
								src -= 2;
								dst -= current_output_channels;
								dst[0] = src[0];
								dst[1] = src[1];
								dst[2] = src[0];
								dst[3] = src[1];
								if (current_output_channels == 6) {
									dst[4] = src[0];
									dst[5] = src[1];
								}
							}
							break;
						case 16:
							for ( i=small_len/4; i; --i ) {
								src -= 4;
								dst -= 2 * current_output_channels;
								dst[0] = src[0];
								dst[1] = src[1];
								dst[2] = src[2];
								dst[3] = src[3];
								dst[4] = src[0];
								dst[5] = src[1];
								dst[6] = src[2];
								dst[7] = src[3];
								if (current_output_channels == 6) {
									dst[8] = src[0];
									dst[9] = src[1];
									dst[10] = src[2];
									dst[11] = src[3];
								}
							}
							break;
					}



				}
				else VC_WriteBytes((SBYTE *)stream, len);
				if ( music_swap8 ) {
					Uint8 *dst;
					int i;

					dst = stream;
					for ( i=len; i; --i ) {
						*dst++ ^= 0x80;
					}
				} else
				if ( music_swap16 ) {
					Uint8 *dst, tmp;
					int i;

					dst = stream;
					for ( i=(len/2); i; --i ) {
						tmp = dst[0];
						dst[0] = dst[1];
						dst[1] = tmp;
						dst += 2;
					}
				}
				break;
#endif
#ifdef MID_MUSIC
#ifdef USE_TIMIDITY_MIDI
			case MUS_MID:
				if ( timidity_ok ) {
					int samples = len / samplesize;
  					Timidity_PlaySome(stream, samples);
				}
				break;
#endif
#endif
#ifdef OGG_MUSIC
			case MUS_OGG:
				
				len = OGG_playAudio(music_playing->data.ogg, stream, len);
				if (len > 0 && music_halt_or_loop())
					OGG_playAudio(music_playing->data.ogg, stream, len);
			
				break;
#endif
#ifdef MP3_MUSIC
			case MUS_MP3:
				smpeg.SMPEG_playAudio(music_playing->data.mp3, stream, len);
				break;
#endif
			default:
				/* Unknown music type?? */
				break;
		}
	}
}

/* Initialize the music players with a certain desired audio format */
int open_music(SDL_AudioSpec *mixer)
{
	int music_error;
#ifdef LIBMIKMOD_MUSIC
	CHAR *list;
#endif

	music_error = 0;
#ifdef WAV_MUSIC
	if ( WAVStream_Init(mixer) < 0 ) {
		++music_error;
	}
#endif
#if defined(MOD_MUSIC) || defined(LIBMIKMOD_MUSIC)
	/* Set the MikMod music format */
	music_swap8 = 0;
	music_swap16 = 0;
	switch (mixer->format) {

		case AUDIO_U8:
		case AUDIO_S8: {
			if ( mixer->format == AUDIO_S8 ) {
				music_swap8 = 1;
			}
			md_mode = 0;
		}
		break;

		case AUDIO_S16LSB:
		case AUDIO_S16MSB: {
			/* See if we need to correct MikMod mixing */
#if SDL_BYTEORDER == SDL_LIL_ENDIAN
			if ( mixer->format == AUDIO_S16MSB ) {
#else
			if ( mixer->format == AUDIO_S16LSB ) {
#endif
				music_swap16 = 1;
			}
			md_mode = DMODE_16BITS;
		}
		break;

		default: {
			Mix_SetError("Unknown hardware audio format");
			++music_error;
		}
	}
	current_output_channels = mixer->channels;
	current_output_format = mixer->format;
	if ( mixer->channels > 1 ) {
		if ( mixer->channels > MAX_OUTPUT_CHANNELS ) {
			Mix_SetError("Hardware uses more channels than mixer");
			++music_error;
		}
		md_mode |= DMODE_STEREO;
	}
	md_mixfreq = mixer->freq;
	md_device  = 0;
	md_volume  = 96;
	md_musicvolume = 128;
	md_sndfxvolume = 128;
	md_pansep  = 128;
	md_reverb  = 0;
	md_mode    |= DMODE_HQMIXER|DMODE_SOFT_MUSIC|DMODE_SURROUND;
#ifdef LIBMIKMOD_MUSIC
	list = MikMod_InfoDriver();
	if ( list )
	  free(list);
	else
#endif
	MikMod_RegisterDriver(&drv_nos);
#ifdef LIBMIKMOD_MUSIC
	list = MikMod_InfoLoader();
	if ( list )
	  free(list);
	else
#endif
	MikMod_RegisterAllLoaders();
	if ( MikMod_Init() ) {
		Mix_SetError("%s", MikMod_strerror(MikMod_errno));
		++music_error;
	}
#endif
#ifdef MID_MUSIC
#ifdef USE_TIMIDITY_MIDI
	samplesize = mixer->size / mixer->samples;
	if ( Timidity_Init(mixer->freq, mixer->format,
	                    mixer->channels, mixer->samples) == 0 ) {
		timidity_ok = 1;
	} else {
		timidity_ok = 0;
	}
#endif
#ifdef USE_NATIVE_MIDI
#ifdef USE_TIMIDITY_MIDI
	native_midi_ok = !timidity_ok;
	if ( native_midi_ok )
#endif
		native_midi_ok = native_midi_detect();
#endif
#endif
#ifdef OGG_MUSIC
	if ( OGG_init(mixer) < 0 ) {
		++music_error;
	}
#endif
#ifdef MP3_MUSIC
	/* Keep a copy of the mixer */
	used_mixer = *mixer;
#endif
	music_playing = NULL;
	music_stopped = 0;
	if ( music_error ) {
		return(-1);
	}
	Mix_VolumeMusic(SDL_MIX_MAXVOLUME);

	/* Calculate the number of ms for each callback */
	ms_per_step = (int) (((float)mixer->samples * 1000.0) / mixer->freq);

	return(0);
}

/* Portable case-insensitive string compare function */
int MIX_string_equals(const char *str1, const char *str2)
{
	while ( *str1 && *str2 ) {
		if ( toupper((unsigned char)*str1) !=
		     toupper((unsigned char)*str2) )
			break;
		++str1;
		++str2;
	}
	return (!*str1 && !*str2);
}

/* Load a music file */