SDL_mixer.h
author Sam Lantinga <slouken@libsdl.org>
Tue, 17 Oct 2017 02:33:47 -0700
changeset 777 92882ef2ab81
parent 757 420f3b37dc95
child 817 aef7a1784ffd
permissions -rw-r--r--
Rewrote music.c to support any number of decode libraries using a compiled-in plugin interface
Mix_LoadWAV_RW() can now load sound formats that were previously available only as music.

This is still work in progress. Testing and project updates need to happen on other platforms.
     1 /*
     2   SDL_mixer:  An audio mixer library based on the SDL library
     3   Copyright (C) 1997-2017 Sam Lantinga <slouken@libsdl.org>
     4 
     5   This software is provided 'as-is', without any express or implied
     6   warranty.  In no event will the authors be held liable for any damages
     7   arising from the use of this software.
     8 
     9   Permission is granted to anyone to use this software for any purpose,
    10   including commercial applications, and to alter it and redistribute it
    11   freely, subject to the following restrictions:
    12 
    13   1. The origin of this software must not be misrepresented; you must not
    14      claim that you wrote the original software. If you use this software
    15      in a product, an acknowledgment in the product documentation would be
    16      appreciated but is not required.
    17   2. Altered source versions must be plainly marked as such, and must not be
    18      misrepresented as being the original software.
    19   3. This notice may not be removed or altered from any source distribution.
    20 */
    21 
    22 /* $Id$ */
    23 
    24 #ifndef SDL_MIXER_H_
    25 #define SDL_MIXER_H_
    26 
    27 #include "SDL_stdinc.h"
    28 #include "SDL_rwops.h"
    29 #include "SDL_audio.h"
    30 #include "SDL_endian.h"
    31 #include "SDL_version.h"
    32 #include "begin_code.h"
    33 
    34 /* Set up for C function definitions, even when using C++ */
    35 #ifdef __cplusplus
    36 extern "C" {
    37 #endif
    38 
    39 /* Printable format: "%d.%d.%d", MAJOR, MINOR, PATCHLEVEL
    40 */
    41 #define SDL_MIXER_MAJOR_VERSION 2
    42 #define SDL_MIXER_MINOR_VERSION 0
    43 #define SDL_MIXER_PATCHLEVEL    2
    44 
    45 /* This macro can be used to fill a version structure with the compile-time
    46  * version of the SDL_mixer library.
    47  */
    48 #define SDL_MIXER_VERSION(X)                        \
    49 {                                                   \
    50     (X)->major = SDL_MIXER_MAJOR_VERSION;           \
    51     (X)->minor = SDL_MIXER_MINOR_VERSION;           \
    52     (X)->patch = SDL_MIXER_PATCHLEVEL;              \
    53 }
    54 
    55 /* Backwards compatibility */
    56 #define MIX_MAJOR_VERSION   SDL_MIXER_MAJOR_VERSION
    57 #define MIX_MINOR_VERSION   SDL_MIXER_MINOR_VERSION
    58 #define MIX_PATCHLEVEL      SDL_MIXER_PATCHLEVEL
    59 #define MIX_VERSION(X)      SDL_MIXER_VERSION(X)
    60 
    61 /* This function gets the version of the dynamically linked SDL_mixer library.
    62    it should NOT be used to fill a version structure, instead you should
    63    use the SDL_MIXER_VERSION() macro.
    64  */
    65 extern DECLSPEC const SDL_version * SDLCALL Mix_Linked_Version(void);
    66 
    67 typedef enum
    68 {
    69     MIX_INIT_FLAC   = 0x00000001,
    70     MIX_INIT_MOD    = 0x00000002,
    71     MIX_INIT_MP3    = 0x00000008,
    72     MIX_INIT_OGG    = 0x00000010,
    73     MIX_INIT_MID    = 0x00000020,
    74 } MIX_InitFlags;
    75 
    76 /* Loads dynamic libraries and prepares them for use.  Flags should be
    77    one or more flags from MIX_InitFlags OR'd together.
    78    It returns the flags successfully initialized, or 0 on failure.
    79  */
    80 extern DECLSPEC int SDLCALL Mix_Init(int flags);
    81 
    82 /* Unloads libraries loaded with Mix_Init */
    83 extern DECLSPEC void SDLCALL Mix_Quit(void);
    84 
    85 
    86 /* The default mixer has 8 simultaneous mixing channels */
    87 #ifndef MIX_CHANNELS
    88 #define MIX_CHANNELS    8
    89 #endif
    90 
    91 /* Good default values for a PC soundcard */
    92 #define MIX_DEFAULT_FREQUENCY   22050
    93 #if SDL_BYTEORDER == SDL_LIL_ENDIAN
    94 #define MIX_DEFAULT_FORMAT  AUDIO_S16LSB
    95 #else
    96 #define MIX_DEFAULT_FORMAT  AUDIO_S16MSB
    97 #endif
    98 #define MIX_DEFAULT_CHANNELS    2
    99 #define MIX_MAX_VOLUME          SDL_MIX_MAXVOLUME /* Volume of a chunk */
   100 
   101 /* The internal format for an audio chunk */
   102 typedef struct Mix_Chunk {
   103     int allocated;
   104     Uint8 *abuf;
   105     Uint32 alen;
   106     Uint8 volume;       /* Per-sample volume, 0-128 */
   107 } Mix_Chunk;
   108 
   109 /* The different fading types supported */
   110 typedef enum {
   111     MIX_NO_FADING,
   112     MIX_FADING_OUT,
   113     MIX_FADING_IN
   114 } Mix_Fading;
   115 
   116 /* These are types of music files (not libraries used to load them) */
   117 typedef enum {
   118     MUS_NONE,
   119     MUS_CMD,
   120     MUS_WAV,
   121     MUS_MOD,
   122     MUS_MID,
   123     MUS_OGG,
   124     MUS_MP3,
   125     MUS_MP3_MAD_UNUSED,
   126     MUS_FLAC,
   127     MUS_MODPLUG_UNUSED
   128 } Mix_MusicType;
   129 
   130 /* The internal format for a music chunk interpreted via mikmod */
   131 typedef struct _Mix_Music Mix_Music;
   132 
   133 /* Open the mixer with a certain audio format */
   134 extern DECLSPEC int SDLCALL Mix_OpenAudio(int frequency, Uint16 format, int channels, int chunksize);
   135 
   136 /* Open the mixer with specific device and certain audio format */
   137 extern DECLSPEC int SDLCALL Mix_OpenAudioDevice(int frequency, Uint16 format, int channels, int chunksize, const char* device, int allowed_changes);
   138 
   139 /* Dynamically change the number of channels managed by the mixer.
   140    If decreasing the number of channels, the upper channels are
   141    stopped.
   142    This function returns the new number of allocated channels.
   143  */
   144 extern DECLSPEC int SDLCALL Mix_AllocateChannels(int numchans);
   145 
   146 /* Find out what the actual audio device parameters are.
   147    This function returns 1 if the audio has been opened, 0 otherwise.
   148  */
   149 extern DECLSPEC int SDLCALL Mix_QuerySpec(int *frequency,Uint16 *format,int *channels);
   150 
   151 /* Load a wave file or a music (.mod .s3m .it .xm) file */
   152 extern DECLSPEC Mix_Chunk * SDLCALL Mix_LoadWAV_RW(SDL_RWops *src, int freesrc);
   153 #define Mix_LoadWAV(file)   Mix_LoadWAV_RW(SDL_RWFromFile(file, "rb"), 1)
   154 extern DECLSPEC Mix_Music * SDLCALL Mix_LoadMUS(const char *file);
   155 
   156 /* Load a music file from an SDL_RWop object (Ogg and MikMod specific currently)
   157    Matt Campbell (matt@campbellhome.dhs.org) April 2000 */
   158 extern DECLSPEC Mix_Music * SDLCALL Mix_LoadMUS_RW(SDL_RWops *src, int freesrc);
   159 
   160 /* Load a music file from an SDL_RWop object assuming a specific format */
   161 extern DECLSPEC Mix_Music * SDLCALL Mix_LoadMUSType_RW(SDL_RWops *src, Mix_MusicType type, int freesrc);
   162 
   163 /* Load a wave file of the mixer format from a memory buffer */
   164 extern DECLSPEC Mix_Chunk * SDLCALL Mix_QuickLoad_WAV(Uint8 *mem);
   165 
   166 /* Load raw audio data of the mixer format from a memory buffer */
   167 extern DECLSPEC Mix_Chunk * SDLCALL Mix_QuickLoad_RAW(Uint8 *mem, Uint32 len);
   168 
   169 /* Free an audio chunk previously loaded */
   170 extern DECLSPEC void SDLCALL Mix_FreeChunk(Mix_Chunk *chunk);
   171 extern DECLSPEC void SDLCALL Mix_FreeMusic(Mix_Music *music);
   172 
   173 /* Get a list of chunk/music decoders that this build of SDL_mixer provides.
   174    This list can change between builds AND runs of the program, if external
   175    libraries that add functionality become available.
   176    You must successfully call Mix_OpenAudio() before calling these functions.
   177    This API is only available in SDL_mixer 1.2.9 and later.
   178 
   179    // usage...
   180    int i;
   181    const int total = Mix_GetNumChunkDecoders();
   182    for (i = 0; i < total; i++)
   183        printf("Supported chunk decoder: [%s]\n", Mix_GetChunkDecoder(i));
   184 
   185    Appearing in this list doesn't promise your specific audio file will
   186    decode...but it's handy to know if you have, say, a functioning Timidity
   187    install.
   188 
   189    These return values are static, read-only data; do not modify or free it.
   190    The pointers remain valid until you call Mix_CloseAudio().
   191 */
   192 extern DECLSPEC int SDLCALL Mix_GetNumChunkDecoders(void);
   193 extern DECLSPEC const char * SDLCALL Mix_GetChunkDecoder(int index);
   194 extern DECLSPEC SDL_bool SDLCALL Mix_HasChunkDecoder(const char *name);
   195 extern DECLSPEC int SDLCALL Mix_GetNumMusicDecoders(void);
   196 extern DECLSPEC const char * SDLCALL Mix_GetMusicDecoder(int index);
   197 extern DECLSPEC SDL_bool SDLCALL Mix_HasMusicDecoder(const char *name);
   198 
   199 /* Find out the music format of a mixer music, or the currently playing
   200    music, if 'music' is NULL.
   201 */
   202 extern DECLSPEC Mix_MusicType SDLCALL Mix_GetMusicType(const Mix_Music *music);
   203 
   204 /* Set a function that is called after all mixing is performed.
   205    This can be used to provide real-time visual display of the audio stream
   206    or add a custom mixer filter for the stream data.
   207 */
   208 extern DECLSPEC void SDLCALL Mix_SetPostMix(void (*mix_func)(void *udata, Uint8 *stream, int len), void *arg);
   209 
   210 /* Add your own music player or additional mixer function.
   211    If 'mix_func' is NULL, the default music player is re-enabled.
   212  */
   213 extern DECLSPEC void SDLCALL Mix_HookMusic(void (*mix_func)(void *udata, Uint8 *stream, int len), void *arg);
   214 
   215 /* Add your own callback for when the music has finished playing or when it is
   216  * stopped from a call to Mix_HaltMusic.
   217  */
   218 extern DECLSPEC void SDLCALL Mix_HookMusicFinished(void (*music_finished)(void));
   219 
   220 /* Get a pointer to the user data for the current music hook */
   221 extern DECLSPEC void * SDLCALL Mix_GetMusicHookData(void);
   222 
   223 /*
   224  * Add your own callback when a channel has finished playing. NULL
   225  *  to disable callback. The callback may be called from the mixer's audio
   226  *  callback or it could be called as a result of Mix_HaltChannel(), etc.
   227  *  do not call SDL_LockAudio() from this callback; you will either be
   228  *  inside the audio callback, or SDL_mixer will explicitly lock the audio
   229  *  before calling your callback.
   230  */
   231 extern DECLSPEC void SDLCALL Mix_ChannelFinished(void (*channel_finished)(int channel));
   232 
   233 
   234 /* Special Effects API by ryan c. gordon. (icculus@icculus.org) */
   235 
   236 #define MIX_CHANNEL_POST  -2
   237 
   238 /* This is the format of a special effect callback:
   239  *
   240  *   myeffect(int chan, void *stream, int len, void *udata);
   241  *
   242  * (chan) is the channel number that your effect is affecting. (stream) is
   243  *  the buffer of data to work upon. (len) is the size of (stream), and
   244  *  (udata) is a user-defined bit of data, which you pass as the last arg of
   245  *  Mix_RegisterEffect(), and is passed back unmolested to your callback.
   246  *  Your effect changes the contents of (stream) based on whatever parameters
   247  *  are significant, or just leaves it be, if you prefer. You can do whatever
   248  *  you like to the buffer, though, and it will continue in its changed state
   249  *  down the mixing pipeline, through any other effect functions, then finally
   250  *  to be mixed with the rest of the channels and music for the final output
   251  *  stream.
   252  *
   253  * DO NOT EVER call SDL_LockAudio() from your callback function!
   254  */
   255 typedef void (*Mix_EffectFunc_t)(int chan, void *stream, int len, void *udata);
   256 
   257 /*
   258  * This is a callback that signifies that a channel has finished all its
   259  *  loops and has completed playback. This gets called if the buffer
   260  *  plays out normally, or if you call Mix_HaltChannel(), implicitly stop
   261  *  a channel via Mix_AllocateChannels(), or unregister a callback while
   262  *  it's still playing.
   263  *
   264  * DO NOT EVER call SDL_LockAudio() from your callback function!
   265  */
   266 typedef void (*Mix_EffectDone_t)(int chan, void *udata);
   267 
   268 
   269 /* Register a special effect function. At mixing time, the channel data is
   270  *  copied into a buffer and passed through each registered effect function.
   271  *  After it passes through all the functions, it is mixed into the final
   272  *  output stream. The copy to buffer is performed once, then each effect
   273  *  function performs on the output of the previous effect. Understand that
   274  *  this extra copy to a buffer is not performed if there are no effects
   275  *  registered for a given chunk, which saves CPU cycles, and any given
   276  *  effect will be extra cycles, too, so it is crucial that your code run
   277  *  fast. Also note that the data that your function is given is in the
   278  *  format of the sound device, and not the format you gave to Mix_OpenAudio(),
   279  *  although they may in reality be the same. This is an unfortunate but
   280  *  necessary speed concern. Use Mix_QuerySpec() to determine if you can
   281  *  handle the data before you register your effect, and take appropriate
   282  *  actions.
   283  * You may also specify a callback (Mix_EffectDone_t) that is called when
   284  *  the channel finishes playing. This gives you a more fine-grained control
   285  *  than Mix_ChannelFinished(), in case you need to free effect-specific
   286  *  resources, etc. If you don't need this, you can specify NULL.
   287  * You may set the callbacks before or after calling Mix_PlayChannel().
   288  * Things like Mix_SetPanning() are just internal special effect functions,
   289  *  so if you are using that, you've already incurred the overhead of a copy
   290  *  to a separate buffer, and that these effects will be in the queue with
   291  *  any functions you've registered. The list of registered effects for a
   292  *  channel is reset when a chunk finishes playing, so you need to explicitly
   293  *  set them with each call to Mix_PlayChannel*().
   294  * You may also register a special effect function that is to be run after
   295  *  final mixing occurs. The rules for these callbacks are identical to those
   296  *  in Mix_RegisterEffect, but they are run after all the channels and the
   297  *  music have been mixed into a single stream, whereas channel-specific
   298  *  effects run on a given channel before any other mixing occurs. These
   299  *  global effect callbacks are call "posteffects". Posteffects only have
   300  *  their Mix_EffectDone_t function called when they are unregistered (since
   301  *  the main output stream is never "done" in the same sense as a channel).
   302  *  You must unregister them manually when you've had enough. Your callback
   303  *  will be told that the channel being mixed is (MIX_CHANNEL_POST) if the
   304  *  processing is considered a posteffect.
   305  *
   306  * After all these effects have finished processing, the callback registered
   307  *  through Mix_SetPostMix() runs, and then the stream goes to the audio
   308  *  device.
   309  *
   310  * DO NOT EVER call SDL_LockAudio() from your callback function!
   311  *
   312  * returns zero if error (no such channel), nonzero if added.
   313  *  Error messages can be retrieved from Mix_GetError().
   314  */
   315 extern DECLSPEC int SDLCALL Mix_RegisterEffect(int chan, Mix_EffectFunc_t f, Mix_EffectDone_t d, void *arg);
   316 
   317 
   318 /* You may not need to call this explicitly, unless you need to stop an
   319  *  effect from processing in the middle of a chunk's playback.
   320  * Posteffects are never implicitly unregistered as they are for channels,
   321  *  but they may be explicitly unregistered through this function by
   322  *  specifying MIX_CHANNEL_POST for a channel.
   323  * returns zero if error (no such channel or effect), nonzero if removed.
   324  *  Error messages can be retrieved from Mix_GetError().
   325  */
   326 extern DECLSPEC int SDLCALL Mix_UnregisterEffect(int channel, Mix_EffectFunc_t f);
   327 
   328 
   329 /* You may not need to call this explicitly, unless you need to stop all
   330  *  effects from processing in the middle of a chunk's playback. Note that
   331  *  this will also shut off some internal effect processing, since
   332  *  Mix_SetPanning() and others may use this API under the hood. This is
   333  *  called internally when a channel completes playback.
   334  * Posteffects are never implicitly unregistered as they are for channels,
   335  *  but they may be explicitly unregistered through this function by
   336  *  specifying MIX_CHANNEL_POST for a channel.
   337  * returns zero if error (no such channel), nonzero if all effects removed.
   338  *  Error messages can be retrieved from Mix_GetError().
   339  */
   340 extern DECLSPEC int SDLCALL Mix_UnregisterAllEffects(int channel);
   341 
   342 
   343 #define MIX_EFFECTSMAXSPEED  "MIX_EFFECTSMAXSPEED"
   344 
   345 /*
   346  * These are the internally-defined mixing effects. They use the same API that
   347  *  effects defined in the application use, but are provided here as a
   348  *  convenience. Some effects can reduce their quality or use more memory in
   349  *  the name of speed; to enable this, make sure the environment variable
   350  *  MIX_EFFECTSMAXSPEED (see above) is defined before you call
   351  *  Mix_OpenAudio().
   352  */
   353 
   354 
   355 /* Set the panning of a channel. The left and right channels are specified
   356  *  as integers between 0 and 255, quietest to loudest, respectively.
   357  *
   358  * Technically, this is just individual volume control for a sample with
   359  *  two (stereo) channels, so it can be used for more than just panning.
   360  *  If you want real panning, call it like this:
   361  *
   362  *   Mix_SetPanning(channel, left, 255 - left);
   363  *
   364  * ...which isn't so hard.
   365  *
   366  * Setting (channel) to MIX_CHANNEL_POST registers this as a posteffect, and
   367  *  the panning will be done to the final mixed stream before passing it on
   368  *  to the audio device.
   369  *
   370  * This uses the Mix_RegisterEffect() API internally, and returns without
   371  *  registering the effect function if the audio device is not configured
   372  *  for stereo output. Setting both (left) and (right) to 255 causes this
   373  *  effect to be unregistered, since that is the data's normal state.
   374  *
   375  * returns zero if error (no such channel or Mix_RegisterEffect() fails),
   376  *  nonzero if panning effect enabled. Note that an audio device in mono
   377  *  mode is a no-op, but this call will return successful in that case.
   378  *  Error messages can be retrieved from Mix_GetError().
   379  */
   380 extern DECLSPEC int SDLCALL Mix_SetPanning(int channel, Uint8 left, Uint8 right);
   381 
   382 
   383 /* Set the position of a channel. (angle) is an integer from 0 to 360, that
   384  *  specifies the location of the sound in relation to the listener. (angle)
   385  *  will be reduced as neccesary (540 becomes 180 degrees, -100 becomes 260).
   386  *  Angle 0 is due north, and rotates clockwise as the value increases.
   387  *  For efficiency, the precision of this effect may be limited (angles 1
   388  *  through 7 might all produce the same effect, 8 through 15 are equal, etc).
   389  *  (distance) is an integer between 0 and 255 that specifies the space
   390  *  between the sound and the listener. The larger the number, the further
   391  *  away the sound is. Using 255 does not guarantee that the channel will be
   392  *  culled from the mixing process or be completely silent. For efficiency,
   393  *  the precision of this effect may be limited (distance 0 through 5 might
   394  *  all produce the same effect, 6 through 10 are equal, etc). Setting (angle)
   395  *  and (distance) to 0 unregisters this effect, since the data would be
   396  *  unchanged.
   397  *
   398  * If you need more precise positional audio, consider using OpenAL for
   399  *  spatialized effects instead of SDL_mixer. This is only meant to be a
   400  *  basic effect for simple "3D" games.
   401  *
   402  * If the audio device is configured for mono output, then you won't get
   403  *  any effectiveness from the angle; however, distance attenuation on the
   404  *  channel will still occur. While this effect will function with stereo
   405  *  voices, it makes more sense to use voices with only one channel of sound,
   406  *  so when they are mixed through this effect, the positioning will sound
   407  *  correct. You can convert them to mono through SDL before giving them to
   408  *  the mixer in the first place if you like.
   409  *
   410  * Setting (channel) to MIX_CHANNEL_POST registers this as a posteffect, and
   411  *  the positioning will be done to the final mixed stream before passing it
   412  *  on to the audio device.
   413  *
   414  * This is a convenience wrapper over Mix_SetDistance() and Mix_SetPanning().
   415  *
   416  * returns zero if error (no such channel or Mix_RegisterEffect() fails),
   417  *  nonzero if position effect is enabled.
   418  *  Error messages can be retrieved from Mix_GetError().
   419  */
   420 extern DECLSPEC int SDLCALL Mix_SetPosition(int channel, Sint16 angle, Uint8 distance);
   421 
   422 
   423 /* Set the "distance" of a channel. (distance) is an integer from 0 to 255
   424  *  that specifies the location of the sound in relation to the listener.
   425  *  Distance 0 is overlapping the listener, and 255 is as far away as possible
   426  *  A distance of 255 does not guarantee silence; in such a case, you might
   427  *  want to try changing the chunk's volume, or just cull the sample from the
   428  *  mixing process with Mix_HaltChannel().
   429  * For efficiency, the precision of this effect may be limited (distances 1
   430  *  through 7 might all produce the same effect, 8 through 15 are equal, etc).
   431  *  (distance) is an integer between 0 and 255 that specifies the space
   432  *  between the sound and the listener. The larger the number, the further
   433  *  away the sound is.
   434  * Setting (distance) to 0 unregisters this effect, since the data would be
   435  *  unchanged.
   436  * If you need more precise positional audio, consider using OpenAL for
   437  *  spatialized effects instead of SDL_mixer. This is only meant to be a
   438  *  basic effect for simple "3D" games.
   439  *
   440  * Setting (channel) to MIX_CHANNEL_POST registers this as a posteffect, and
   441  *  the distance attenuation will be done to the final mixed stream before
   442  *  passing it on to the audio device.
   443  *
   444  * This uses the Mix_RegisterEffect() API internally.
   445  *
   446  * returns zero if error (no such channel or Mix_RegisterEffect() fails),
   447  *  nonzero if position effect is enabled.
   448  *  Error messages can be retrieved from Mix_GetError().
   449  */
   450 extern DECLSPEC int SDLCALL Mix_SetDistance(int channel, Uint8 distance);
   451 
   452 
   453 /*
   454  * !!! FIXME : Haven't implemented, since the effect goes past the
   455  *              end of the sound buffer. Will have to think about this.
   456  *               --ryan.
   457  */
   458 #if 0
   459 /* Causes an echo effect to be mixed into a sound. (echo) is the amount
   460  *  of echo to mix. 0 is no echo, 255 is infinite (and probably not
   461  *  what you want).
   462  *
   463  * Setting (channel) to MIX_CHANNEL_POST registers this as a posteffect, and
   464  *  the reverbing will be done to the final mixed stream before passing it on
   465  *  to the audio device.
   466  *
   467  * This uses the Mix_RegisterEffect() API internally. If you specify an echo
   468  *  of zero, the effect is unregistered, as the data is already in that state.
   469  *
   470  * returns zero if error (no such channel or Mix_RegisterEffect() fails),
   471  *  nonzero if reversing effect is enabled.
   472  *  Error messages can be retrieved from Mix_GetError().
   473  */
   474 extern no_parse_DECLSPEC int SDLCALL Mix_SetReverb(int channel, Uint8 echo);
   475 #endif
   476 
   477 /* Causes a channel to reverse its stereo. This is handy if the user has his
   478  *  speakers hooked up backwards, or you would like to have a minor bit of
   479  *  psychedelia in your sound code.  :)  Calling this function with (flip)
   480  *  set to non-zero reverses the chunks's usual channels. If (flip) is zero,
   481  *  the effect is unregistered.
   482  *
   483  * This uses the Mix_RegisterEffect() API internally, and thus is probably
   484  *  more CPU intensive than having the user just plug in his speakers
   485  *  correctly. Mix_SetReverseStereo() returns without registering the effect
   486  *  function if the audio device is not configured for stereo output.
   487  *
   488  * If you specify MIX_CHANNEL_POST for (channel), then this the effect is used
   489  *  on the final mixed stream before sending it on to the audio device (a
   490  *  posteffect).
   491  *
   492  * returns zero if error (no such channel or Mix_RegisterEffect() fails),
   493  *  nonzero if reversing effect is enabled. Note that an audio device in mono
   494  *  mode is a no-op, but this call will return successful in that case.
   495  *  Error messages can be retrieved from Mix_GetError().
   496  */
   497 extern DECLSPEC int SDLCALL Mix_SetReverseStereo(int channel, int flip);
   498 
   499 /* end of effects API. --ryan. */
   500 
   501 
   502 /* Reserve the first channels (0 -> n-1) for the application, i.e. don't allocate
   503    them dynamically to the next sample if requested with a -1 value below.
   504    Returns the number of reserved channels.
   505  */
   506 extern DECLSPEC int SDLCALL Mix_ReserveChannels(int num);
   507 
   508 /* Channel grouping functions */
   509 
   510 /* Attach a tag to a channel. A tag can be assigned to several mixer
   511    channels, to form groups of channels.
   512    If 'tag' is -1, the tag is removed (actually -1 is the tag used to
   513    represent the group of all the channels).
   514    Returns true if everything was OK.
   515  */
   516 extern DECLSPEC int SDLCALL Mix_GroupChannel(int which, int tag);
   517 /* Assign several consecutive channels to a group */
   518 extern DECLSPEC int SDLCALL Mix_GroupChannels(int from, int to, int tag);
   519 /* Finds the first available channel in a group of channels,
   520    returning -1 if none are available.
   521  */
   522 extern DECLSPEC int SDLCALL Mix_GroupAvailable(int tag);
   523 /* Returns the number of channels in a group. This is also a subtle
   524    way to get the total number of channels when 'tag' is -1
   525  */
   526 extern DECLSPEC int SDLCALL Mix_GroupCount(int tag);
   527 /* Finds the "oldest" sample playing in a group of channels */
   528 extern DECLSPEC int SDLCALL Mix_GroupOldest(int tag);
   529 /* Finds the "most recent" (i.e. last) sample playing in a group of channels */
   530 extern DECLSPEC int SDLCALL Mix_GroupNewer(int tag);
   531 
   532 /* Play an audio chunk on a specific channel.
   533    If the specified channel is -1, play on the first free channel.
   534    If 'loops' is greater than zero, loop the sound that many times.
   535    If 'loops' is -1, loop inifinitely (~65000 times).
   536    Returns which channel was used to play the sound.
   537 */
   538 #define Mix_PlayChannel(channel,chunk,loops) Mix_PlayChannelTimed(channel,chunk,loops,-1)
   539 /* The same as above, but the sound is played at most 'ticks' milliseconds */
   540 extern DECLSPEC int SDLCALL Mix_PlayChannelTimed(int channel, Mix_Chunk *chunk, int loops, int ticks);
   541 extern DECLSPEC int SDLCALL Mix_PlayMusic(Mix_Music *music, int loops);
   542 
   543 /* Fade in music or a channel over "ms" milliseconds, same semantics as the "Play" functions */
   544 extern DECLSPEC int SDLCALL Mix_FadeInMusic(Mix_Music *music, int loops, int ms);
   545 extern DECLSPEC int SDLCALL Mix_FadeInMusicPos(Mix_Music *music, int loops, int ms, double position);
   546 #define Mix_FadeInChannel(channel,chunk,loops,ms) Mix_FadeInChannelTimed(channel,chunk,loops,ms,-1)
   547 extern DECLSPEC int SDLCALL Mix_FadeInChannelTimed(int channel, Mix_Chunk *chunk, int loops, int ms, int ticks);
   548 
   549 /* Set the volume in the range of 0-128 of a specific channel or chunk.
   550    If the specified channel is -1, set volume for all channels.
   551    Returns the original volume.
   552    If the specified volume is -1, just return the current volume.
   553 */
   554 extern DECLSPEC int SDLCALL Mix_Volume(int channel, int volume);
   555 extern DECLSPEC int SDLCALL Mix_VolumeChunk(Mix_Chunk *chunk, int volume);
   556 extern DECLSPEC int SDLCALL Mix_VolumeMusic(int volume);
   557 
   558 /* Halt playing of a particular channel */
   559 extern DECLSPEC int SDLCALL Mix_HaltChannel(int channel);
   560 extern DECLSPEC int SDLCALL Mix_HaltGroup(int tag);
   561 extern DECLSPEC int SDLCALL Mix_HaltMusic(void);
   562 
   563 /* Change the expiration delay for a particular channel.
   564    The sample will stop playing after the 'ticks' milliseconds have elapsed,
   565    or remove the expiration if 'ticks' is -1
   566 */
   567 extern DECLSPEC int SDLCALL Mix_ExpireChannel(int channel, int ticks);
   568 
   569 /* Halt a channel, fading it out progressively till it's silent
   570    The ms parameter indicates the number of milliseconds the fading
   571    will take.
   572  */
   573 extern DECLSPEC int SDLCALL Mix_FadeOutChannel(int which, int ms);
   574 extern DECLSPEC int SDLCALL Mix_FadeOutGroup(int tag, int ms);
   575 extern DECLSPEC int SDLCALL Mix_FadeOutMusic(int ms);
   576 
   577 /* Query the fading status of a channel */
   578 extern DECLSPEC Mix_Fading SDLCALL Mix_FadingMusic(void);
   579 extern DECLSPEC Mix_Fading SDLCALL Mix_FadingChannel(int which);
   580 
   581 /* Pause/Resume a particular channel */
   582 extern DECLSPEC void SDLCALL Mix_Pause(int channel);
   583 extern DECLSPEC void SDLCALL Mix_Resume(int channel);
   584 extern DECLSPEC int SDLCALL Mix_Paused(int channel);
   585 
   586 /* Pause/Resume the music stream */
   587 extern DECLSPEC void SDLCALL Mix_PauseMusic(void);
   588 extern DECLSPEC void SDLCALL Mix_ResumeMusic(void);
   589 extern DECLSPEC void SDLCALL Mix_RewindMusic(void);
   590 extern DECLSPEC int SDLCALL Mix_PausedMusic(void);
   591 
   592 /* Set the current position in the music stream.
   593    This returns 0 if successful, or -1 if it failed or isn't implemented.
   594    This function is only implemented for MOD music formats (set pattern
   595    order number) and for OGG, FLAC, MP3_MAD, MP3_MPG and MODPLUG music
   596    (set position in seconds), at the moment.
   597 */
   598 extern DECLSPEC int SDLCALL Mix_SetMusicPosition(double position);
   599 
   600 /* Check the status of a specific channel.
   601    If the specified channel is -1, check all channels.
   602 */
   603 extern DECLSPEC int SDLCALL Mix_Playing(int channel);
   604 extern DECLSPEC int SDLCALL Mix_PlayingMusic(void);
   605 
   606 /* Stop music and set external music playback command */
   607 extern DECLSPEC int SDLCALL Mix_SetMusicCMD(const char *command);
   608 
   609 /* Synchro value is set by MikMod from modules while playing */
   610 extern DECLSPEC int SDLCALL Mix_SetSynchroValue(int value);
   611 extern DECLSPEC int SDLCALL Mix_GetSynchroValue(void);
   612 
   613 /* Set/Get/Iterate SoundFonts paths to use by supported MIDI backends */
   614 extern DECLSPEC int SDLCALL Mix_SetSoundFonts(const char *paths);
   615 extern DECLSPEC const char* SDLCALL Mix_GetSoundFonts(void);
   616 extern DECLSPEC int SDLCALL Mix_EachSoundFont(int (*function)(const char*, void*), void *data);
   617 
   618 /* Get the Mix_Chunk currently associated with a mixer channel
   619     Returns NULL if it's an invalid channel, or there's no chunk associated.
   620 */
   621 extern DECLSPEC Mix_Chunk * SDLCALL Mix_GetChunk(int channel);
   622 
   623 /* Close the mixer, halting all playing audio */
   624 extern DECLSPEC void SDLCALL Mix_CloseAudio(void);
   625 
   626 /* We'll use SDL for reporting errors */
   627 #define Mix_SetError    SDL_SetError
   628 #define Mix_GetError    SDL_GetError
   629 #define Mix_ClearError  SDL_ClearError
   630 
   631 /* Ends C function definitions when using C++ */
   632 #ifdef __cplusplus
   633 }
   634 #endif
   635 #include "close_code.h"
   636 
   637 #endif /* SDL_MIXER_H_ */
   638 
   639 /* vi: set ts=4 sw=4 expandtab: */