SDL_mixer.h
author Sam Lantinga <slouken@libsdl.org>
Fri, 29 Jan 2016 12:44:13 -0800
changeset 718 fb0562cc1559
parent 712 7e59d684b070
child 724 810eeaa24633
permissions -rw-r--r--
Added Mix_OpenAudioDevice() so you can specify the audio device to open
     1 /*
     2   SDL_mixer:  An audio mixer library based on the SDL library
     3   Copyright (C) 1997-2016 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    1
    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_MODPLUG     = 0x00000004,
    72     MIX_INIT_MP3         = 0x00000008,
    73     MIX_INIT_OGG         = 0x00000010,
    74     MIX_INIT_FLUIDSYNTH  = 0x00000020
    75 } MIX_InitFlags;
    76 
    77 /* Loads dynamic libraries and prepares them for use.  Flags should be
    78    one or more flags from MIX_InitFlags OR'd together.
    79    It returns the flags successfully initialized, or 0 on failure.
    80  */
    81 extern DECLSPEC int SDLCALL Mix_Init(int flags);
    82 
    83 /* Unloads libraries loaded with Mix_Init */
    84 extern DECLSPEC void SDLCALL Mix_Quit(void);
    85 
    86 
    87 /* The default mixer has 8 simultaneous mixing channels */
    88 #ifndef MIX_CHANNELS
    89 #define MIX_CHANNELS    8
    90 #endif
    91 
    92 /* Good default values for a PC soundcard */
    93 #define MIX_DEFAULT_FREQUENCY   22050
    94 #if SDL_BYTEORDER == SDL_LIL_ENDIAN
    95 #define MIX_DEFAULT_FORMAT  AUDIO_S16LSB
    96 #else
    97 #define MIX_DEFAULT_FORMAT  AUDIO_S16MSB
    98 #endif
    99 #define MIX_DEFAULT_CHANNELS    2
   100 #define MIX_MAX_VOLUME          128 /* Volume of a chunk */
   101 
   102 /* The internal format for an audio chunk */
   103 typedef struct Mix_Chunk {
   104     int allocated;
   105     Uint8 *abuf;
   106     Uint32 alen;
   107     Uint8 volume;       /* Per-sample volume, 0-128 */
   108 } Mix_Chunk;
   109 
   110 /* The different fading types supported */
   111 typedef enum {
   112     MIX_NO_FADING,
   113     MIX_FADING_OUT,
   114     MIX_FADING_IN
   115 } Mix_Fading;
   116 
   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,
   126     MUS_FLAC,
   127     MUS_MODPLUG
   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 int SDLCALL Mix_GetNumMusicDecoders(void);
   195 extern DECLSPEC const char * SDLCALL Mix_GetMusicDecoder(int index);
   196 
   197 /* Find out the music format of a mixer music, or the currently playing
   198    music, if 'music' is NULL.
   199 */
   200 extern DECLSPEC Mix_MusicType SDLCALL Mix_GetMusicType(const Mix_Music *music);
   201 
   202 /* Set a function that is called after all mixing is performed.
   203    This can be used to provide real-time visual display of the audio stream
   204    or add a custom mixer filter for the stream data.
   205 */
   206 extern DECLSPEC void SDLCALL Mix_SetPostMix(void (*mix_func)(void *udata, Uint8 *stream, int len), void *arg);
   207 
   208 /* Add your own music player or additional mixer function.
   209    If 'mix_func' is NULL, the default music player is re-enabled.
   210  */
   211 extern DECLSPEC void SDLCALL Mix_HookMusic(void (*mix_func)(void *udata, Uint8 *stream, int len), void *arg);
   212 
   213 /* Add your own callback for when the music has finished playing or when it is
   214  * stopped from a call to Mix_HaltMusic.
   215  */
   216 extern DECLSPEC void SDLCALL Mix_HookMusicFinished(void (*music_finished)(void));
   217 
   218 /* Get a pointer to the user data for the current music hook */
   219 extern DECLSPEC void * SDLCALL Mix_GetMusicHookData(void);
   220 
   221 /*
   222  * Add your own callback when a channel has finished playing. NULL
   223  *  to disable callback. The callback may be called from the mixer's audio
   224  *  callback or it could be called as a result of Mix_HaltChannel(), etc.
   225  *  do not call SDL_LockAudio() from this callback; you will either be
   226  *  inside the audio callback, or SDL_mixer will explicitly lock the audio
   227  *  before calling your callback.
   228  */
   229 extern DECLSPEC void SDLCALL Mix_ChannelFinished(void (*channel_finished)(int channel));
   230 
   231 
   232 /* Special Effects API by ryan c. gordon. (icculus@icculus.org) */
   233 
   234 #define MIX_CHANNEL_POST  -2
   235 
   236 /* This is the format of a special effect callback:
   237  *
   238  *   myeffect(int chan, void *stream, int len, void *udata);
   239  *
   240  * (chan) is the channel number that your effect is affecting. (stream) is
   241  *  the buffer of data to work upon. (len) is the size of (stream), and
   242  *  (udata) is a user-defined bit of data, which you pass as the last arg of
   243  *  Mix_RegisterEffect(), and is passed back unmolested to your callback.
   244  *  Your effect changes the contents of (stream) based on whatever parameters
   245  *  are significant, or just leaves it be, if you prefer. You can do whatever
   246  *  you like to the buffer, though, and it will continue in its changed state
   247  *  down the mixing pipeline, through any other effect functions, then finally
   248  *  to be mixed with the rest of the channels and music for the final output
   249  *  stream.
   250  *
   251  * DO NOT EVER call SDL_LockAudio() from your callback function!
   252  */
   253 typedef void (*Mix_EffectFunc_t)(int chan, void *stream, int len, void *udata);
   254 
   255 /*
   256  * This is a callback that signifies that a channel has finished all its
   257  *  loops and has completed playback. This gets called if the buffer
   258  *  plays out normally, or if you call Mix_HaltChannel(), implicitly stop
   259  *  a channel via Mix_AllocateChannels(), or unregister a callback while
   260  *  it's still playing.
   261  *
   262  * DO NOT EVER call SDL_LockAudio() from your callback function!
   263  */
   264 typedef void (*Mix_EffectDone_t)(int chan, void *udata);
   265 
   266 
   267 /* Register a special effect function. At mixing time, the channel data is
   268  *  copied into a buffer and passed through each registered effect function.
   269  *  After it passes through all the functions, it is mixed into the final
   270  *  output stream. The copy to buffer is performed once, then each effect
   271  *  function performs on the output of the previous effect. Understand that
   272  *  this extra copy to a buffer is not performed if there are no effects
   273  *  registered for a given chunk, which saves CPU cycles, and any given
   274  *  effect will be extra cycles, too, so it is crucial that your code run
   275  *  fast. Also note that the data that your function is given is in the
   276  *  format of the sound device, and not the format you gave to Mix_OpenAudio(),
   277  *  although they may in reality be the same. This is an unfortunate but
   278  *  necessary speed concern. Use Mix_QuerySpec() to determine if you can
   279  *  handle the data before you register your effect, and take appropriate
   280  *  actions.
   281  * You may also specify a callback (Mix_EffectDone_t) that is called when
   282  *  the channel finishes playing. This gives you a more fine-grained control
   283  *  than Mix_ChannelFinished(), in case you need to free effect-specific
   284  *  resources, etc. If you don't need this, you can specify NULL.
   285  * You may set the callbacks before or after calling Mix_PlayChannel().
   286  * Things like Mix_SetPanning() are just internal special effect functions,
   287  *  so if you are using that, you've already incurred the overhead of a copy
   288  *  to a separate buffer, and that these effects will be in the queue with
   289  *  any functions you've registered. The list of registered effects for a
   290  *  channel is reset when a chunk finishes playing, so you need to explicitly
   291  *  set them with each call to Mix_PlayChannel*().
   292  * You may also register a special effect function that is to be run after
   293  *  final mixing occurs. The rules for these callbacks are identical to those
   294  *  in Mix_RegisterEffect, but they are run after all the channels and the
   295  *  music have been mixed into a single stream, whereas channel-specific
   296  *  effects run on a given channel before any other mixing occurs. These
   297  *  global effect callbacks are call "posteffects". Posteffects only have
   298  *  their Mix_EffectDone_t function called when they are unregistered (since
   299  *  the main output stream is never "done" in the same sense as a channel).
   300  *  You must unregister them manually when you've had enough. Your callback
   301  *  will be told that the channel being mixed is (MIX_CHANNEL_POST) if the
   302  *  processing is considered a posteffect.
   303  *
   304  * After all these effects have finished processing, the callback registered
   305  *  through Mix_SetPostMix() runs, and then the stream goes to the audio
   306  *  device.
   307  *
   308  * DO NOT EVER call SDL_LockAudio() from your callback function!
   309  *
   310  * returns zero if error (no such channel), nonzero if added.
   311  *  Error messages can be retrieved from Mix_GetError().
   312  */
   313 extern DECLSPEC int SDLCALL Mix_RegisterEffect(int chan, Mix_EffectFunc_t f, Mix_EffectDone_t d, void *arg);
   314 
   315 
   316 /* You may not need to call this explicitly, unless you need to stop an
   317  *  effect from processing in the middle of a chunk's playback.
   318  * Posteffects are never implicitly unregistered as they are for channels,
   319  *  but they may be explicitly unregistered through this function by
   320  *  specifying MIX_CHANNEL_POST for a channel.
   321  * returns zero if error (no such channel or effect), nonzero if removed.
   322  *  Error messages can be retrieved from Mix_GetError().
   323  */
   324 extern DECLSPEC int SDLCALL Mix_UnregisterEffect(int channel, Mix_EffectFunc_t f);
   325 
   326 
   327 /* You may not need to call this explicitly, unless you need to stop all
   328  *  effects from processing in the middle of a chunk's playback. Note that
   329  *  this will also shut off some internal effect processing, since
   330  *  Mix_SetPanning() and others may use this API under the hood. This is
   331  *  called internally when a channel completes playback.
   332  * Posteffects are never implicitly unregistered as they are for channels,
   333  *  but they may be explicitly unregistered through this function by
   334  *  specifying MIX_CHANNEL_POST for a channel.
   335  * returns zero if error (no such channel), nonzero if all effects removed.
   336  *  Error messages can be retrieved from Mix_GetError().
   337  */
   338 extern DECLSPEC int SDLCALL Mix_UnregisterAllEffects(int channel);
   339 
   340 
   341 #define MIX_EFFECTSMAXSPEED  "MIX_EFFECTSMAXSPEED"
   342 
   343 /*
   344  * These are the internally-defined mixing effects. They use the same API that
   345  *  effects defined in the application use, but are provided here as a
   346  *  convenience. Some effects can reduce their quality or use more memory in
   347  *  the name of speed; to enable this, make sure the environment variable
   348  *  MIX_EFFECTSMAXSPEED (see above) is defined before you call
   349  *  Mix_OpenAudio().
   350  */
   351 
   352 
   353 /* Set the panning of a channel. The left and right channels are specified
   354  *  as integers between 0 and 255, quietest to loudest, respectively.
   355  *
   356  * Technically, this is just individual volume control for a sample with
   357  *  two (stereo) channels, so it can be used for more than just panning.
   358  *  If you want real panning, call it like this:
   359  *
   360  *   Mix_SetPanning(channel, left, 255 - left);
   361  *
   362  * ...which isn't so hard.
   363  *
   364  * Setting (channel) to MIX_CHANNEL_POST registers this as a posteffect, and
   365  *  the panning will be done to the final mixed stream before passing it on
   366  *  to the audio device.
   367  *
   368  * This uses the Mix_RegisterEffect() API internally, and returns without
   369  *  registering the effect function if the audio device is not configured
   370  *  for stereo output. Setting both (left) and (right) to 255 causes this
   371  *  effect to be unregistered, since that is the data's normal state.
   372  *
   373  * returns zero if error (no such channel or Mix_RegisterEffect() fails),
   374  *  nonzero if panning effect enabled. Note that an audio device in mono
   375  *  mode is a no-op, but this call will return successful in that case.
   376  *  Error messages can be retrieved from Mix_GetError().
   377  */
   378 extern DECLSPEC int SDLCALL Mix_SetPanning(int channel, Uint8 left, Uint8 right);
   379 
   380 
   381 /* Set the position of a channel. (angle) is an integer from 0 to 360, that
   382  *  specifies the location of the sound in relation to the listener. (angle)
   383  *  will be reduced as neccesary (540 becomes 180 degrees, -100 becomes 260).
   384  *  Angle 0 is due north, and rotates clockwise as the value increases.
   385  *  For efficiency, the precision of this effect may be limited (angles 1
   386  *  through 7 might all produce the same effect, 8 through 15 are equal, etc).
   387  *  (distance) is an integer between 0 and 255 that specifies the space
   388  *  between the sound and the listener. The larger the number, the further
   389  *  away the sound is. Using 255 does not guarantee that the channel will be
   390  *  culled from the mixing process or be completely silent. For efficiency,
   391  *  the precision of this effect may be limited (distance 0 through 5 might
   392  *  all produce the same effect, 6 through 10 are equal, etc). Setting (angle)
   393  *  and (distance) to 0 unregisters this effect, since the data would be
   394  *  unchanged.
   395  *
   396  * If you need more precise positional audio, consider using OpenAL for
   397  *  spatialized effects instead of SDL_mixer. This is only meant to be a
   398  *  basic effect for simple "3D" games.
   399  *
   400  * If the audio device is configured for mono output, then you won't get
   401  *  any effectiveness from the angle; however, distance attenuation on the
   402  *  channel will still occur. While this effect will function with stereo
   403  *  voices, it makes more sense to use voices with only one channel of sound,
   404  *  so when they are mixed through this effect, the positioning will sound
   405  *  correct. You can convert them to mono through SDL before giving them to
   406  *  the mixer in the first place if you like.
   407  *
   408  * Setting (channel) to MIX_CHANNEL_POST registers this as a posteffect, and
   409  *  the positioning will be done to the final mixed stream before passing it
   410  *  on to the audio device.
   411  *
   412  * This is a convenience wrapper over Mix_SetDistance() and Mix_SetPanning().
   413  *
   414  * returns zero if error (no such channel or Mix_RegisterEffect() fails),
   415  *  nonzero if position effect is enabled.
   416  *  Error messages can be retrieved from Mix_GetError().
   417  */
   418 extern DECLSPEC int SDLCALL Mix_SetPosition(int channel, Sint16 angle, Uint8 distance);
   419 
   420 
   421 /* Set the "distance" of a channel. (distance) is an integer from 0 to 255
   422  *  that specifies the location of the sound in relation to the listener.
   423  *  Distance 0 is overlapping the listener, and 255 is as far away as possible
   424  *  A distance of 255 does not guarantee silence; in such a case, you might
   425  *  want to try changing the chunk's volume, or just cull the sample from the
   426  *  mixing process with Mix_HaltChannel().
   427  * For efficiency, the precision of this effect may be limited (distances 1
   428  *  through 7 might all produce the same effect, 8 through 15 are equal, etc).
   429  *  (distance) is an integer between 0 and 255 that specifies the space
   430  *  between the sound and the listener. The larger the number, the further
   431  *  away the sound is.
   432  * Setting (distance) to 0 unregisters this effect, since the data would be
   433  *  unchanged.
   434  * If you need more precise positional audio, consider using OpenAL for
   435  *  spatialized effects instead of SDL_mixer. This is only meant to be a
   436  *  basic effect for simple "3D" games.
   437  *
   438  * Setting (channel) to MIX_CHANNEL_POST registers this as a posteffect, and
   439  *  the distance attenuation will be done to the final mixed stream before
   440  *  passing it on to the audio device.
   441  *
   442  * This uses the Mix_RegisterEffect() API internally.
   443  *
   444  * returns zero if error (no such channel or Mix_RegisterEffect() fails),
   445  *  nonzero if position effect is enabled.
   446  *  Error messages can be retrieved from Mix_GetError().
   447  */
   448 extern DECLSPEC int SDLCALL Mix_SetDistance(int channel, Uint8 distance);
   449 
   450 
   451 /*
   452  * !!! FIXME : Haven't implemented, since the effect goes past the
   453  *              end of the sound buffer. Will have to think about this.
   454  *               --ryan.
   455  */
   456 #if 0
   457 /* Causes an echo effect to be mixed into a sound. (echo) is the amount
   458  *  of echo to mix. 0 is no echo, 255 is infinite (and probably not
   459  *  what you want).
   460  *
   461  * Setting (channel) to MIX_CHANNEL_POST registers this as a posteffect, and
   462  *  the reverbing will be done to the final mixed stream before passing it on
   463  *  to the audio device.
   464  *
   465  * This uses the Mix_RegisterEffect() API internally. If you specify an echo
   466  *  of zero, the effect is unregistered, as the data is already in that state.
   467  *
   468  * returns zero if error (no such channel or Mix_RegisterEffect() fails),
   469  *  nonzero if reversing effect is enabled.
   470  *  Error messages can be retrieved from Mix_GetError().
   471  */
   472 extern no_parse_DECLSPEC int SDLCALL Mix_SetReverb(int channel, Uint8 echo);
   473 #endif
   474 
   475 /* Causes a channel to reverse its stereo. This is handy if the user has his
   476  *  speakers hooked up backwards, or you would like to have a minor bit of
   477  *  psychedelia in your sound code.  :)  Calling this function with (flip)
   478  *  set to non-zero reverses the chunks's usual channels. If (flip) is zero,
   479  *  the effect is unregistered.
   480  *
   481  * This uses the Mix_RegisterEffect() API internally, and thus is probably
   482  *  more CPU intensive than having the user just plug in his speakers
   483  *  correctly. Mix_SetReverseStereo() returns without registering the effect
   484  *  function if the audio device is not configured for stereo output.
   485  *
   486  * If you specify MIX_CHANNEL_POST for (channel), then this the effect is used
   487  *  on the final mixed stream before sending it on to the audio device (a
   488  *  posteffect).
   489  *
   490  * returns zero if error (no such channel or Mix_RegisterEffect() fails),
   491  *  nonzero if reversing effect is enabled. Note that an audio device in mono
   492  *  mode is a no-op, but this call will return successful in that case.
   493  *  Error messages can be retrieved from Mix_GetError().
   494  */
   495 extern DECLSPEC int SDLCALL Mix_SetReverseStereo(int channel, int flip);
   496 
   497 /* end of effects API. --ryan. */
   498 
   499 
   500 /* Reserve the first channels (0 -> n-1) for the application, i.e. don't allocate
   501    them dynamically to the next sample if requested with a -1 value below.
   502    Returns the number of reserved channels.
   503  */
   504 extern DECLSPEC int SDLCALL Mix_ReserveChannels(int num);
   505 
   506 /* Channel grouping functions */
   507 
   508 /* Attach a tag to a channel. A tag can be assigned to several mixer
   509    channels, to form groups of channels.
   510    If 'tag' is -1, the tag is removed (actually -1 is the tag used to
   511    represent the group of all the channels).
   512    Returns true if everything was OK.
   513  */
   514 extern DECLSPEC int SDLCALL Mix_GroupChannel(int which, int tag);
   515 /* Assign several consecutive channels to a group */
   516 extern DECLSPEC int SDLCALL Mix_GroupChannels(int from, int to, int tag);
   517 /* Finds the first available channel in a group of channels,
   518    returning -1 if none are available.
   519  */
   520 extern DECLSPEC int SDLCALL Mix_GroupAvailable(int tag);
   521 /* Returns the number of channels in a group. This is also a subtle
   522    way to get the total number of channels when 'tag' is -1
   523  */
   524 extern DECLSPEC int SDLCALL Mix_GroupCount(int tag);
   525 /* Finds the "oldest" sample playing in a group of channels */
   526 extern DECLSPEC int SDLCALL Mix_GroupOldest(int tag);
   527 /* Finds the "most recent" (i.e. last) sample playing in a group of channels */
   528 extern DECLSPEC int SDLCALL Mix_GroupNewer(int tag);
   529 
   530 /* Play an audio chunk on a specific channel.
   531    If the specified channel is -1, play on the first free channel.
   532    If 'loops' is greater than zero, loop the sound that many times.
   533    If 'loops' is -1, loop inifinitely (~65000 times).
   534    Returns which channel was used to play the sound.
   535 */
   536 #define Mix_PlayChannel(channel,chunk,loops) Mix_PlayChannelTimed(channel,chunk,loops,-1)
   537 /* The same as above, but the sound is played at most 'ticks' milliseconds */
   538 extern DECLSPEC int SDLCALL Mix_PlayChannelTimed(int channel, Mix_Chunk *chunk, int loops, int ticks);
   539 extern DECLSPEC int SDLCALL Mix_PlayMusic(Mix_Music *music, int loops);
   540 
   541 /* Fade in music or a channel over "ms" milliseconds, same semantics as the "Play" functions */
   542 extern DECLSPEC int SDLCALL Mix_FadeInMusic(Mix_Music *music, int loops, int ms);
   543 extern DECLSPEC int SDLCALL Mix_FadeInMusicPos(Mix_Music *music, int loops, int ms, double position);
   544 #define Mix_FadeInChannel(channel,chunk,loops,ms) Mix_FadeInChannelTimed(channel,chunk,loops,ms,-1)
   545 extern DECLSPEC int SDLCALL Mix_FadeInChannelTimed(int channel, Mix_Chunk *chunk, int loops, int ms, int ticks);
   546 
   547 /* Set the volume in the range of 0-128 of a specific channel or chunk.
   548    If the specified channel is -1, set volume for all channels.
   549    Returns the original volume.
   550    If the specified volume is -1, just return the current volume.
   551 */
   552 extern DECLSPEC int SDLCALL Mix_Volume(int channel, int volume);
   553 extern DECLSPEC int SDLCALL Mix_VolumeChunk(Mix_Chunk *chunk, int volume);
   554 extern DECLSPEC int SDLCALL Mix_VolumeMusic(int volume);
   555 
   556 /* Halt playing of a particular channel */
   557 extern DECLSPEC int SDLCALL Mix_HaltChannel(int channel);
   558 extern DECLSPEC int SDLCALL Mix_HaltGroup(int tag);
   559 extern DECLSPEC int SDLCALL Mix_HaltMusic(void);
   560 
   561 /* Change the expiration delay for a particular channel.
   562    The sample will stop playing after the 'ticks' milliseconds have elapsed,
   563    or remove the expiration if 'ticks' is -1
   564 */
   565 extern DECLSPEC int SDLCALL Mix_ExpireChannel(int channel, int ticks);
   566 
   567 /* Halt a channel, fading it out progressively till it's silent
   568    The ms parameter indicates the number of milliseconds the fading
   569    will take.
   570  */
   571 extern DECLSPEC int SDLCALL Mix_FadeOutChannel(int which, int ms);
   572 extern DECLSPEC int SDLCALL Mix_FadeOutGroup(int tag, int ms);
   573 extern DECLSPEC int SDLCALL Mix_FadeOutMusic(int ms);
   574 
   575 /* Query the fading status of a channel */
   576 extern DECLSPEC Mix_Fading SDLCALL Mix_FadingMusic(void);
   577 extern DECLSPEC Mix_Fading SDLCALL Mix_FadingChannel(int which);
   578 
   579 /* Pause/Resume a particular channel */
   580 extern DECLSPEC void SDLCALL Mix_Pause(int channel);
   581 extern DECLSPEC void SDLCALL Mix_Resume(int channel);
   582 extern DECLSPEC int SDLCALL Mix_Paused(int channel);
   583 
   584 /* Pause/Resume the music stream */
   585 extern DECLSPEC void SDLCALL Mix_PauseMusic(void);
   586 extern DECLSPEC void SDLCALL Mix_ResumeMusic(void);
   587 extern DECLSPEC void SDLCALL Mix_RewindMusic(void);
   588 extern DECLSPEC int SDLCALL Mix_PausedMusic(void);
   589 
   590 /* Set the current position in the music stream.
   591    This returns 0 if successful, or -1 if it failed or isn't implemented.
   592    This function is only implemented for MOD music formats (set pattern
   593    order number) and for OGG, FLAC, MP3_MAD, and MODPLUG music (set
   594    position in seconds), at the moment.
   595 */
   596 extern DECLSPEC int SDLCALL Mix_SetMusicPosition(double position);
   597 
   598 /* Check the status of a specific channel.
   599    If the specified channel is -1, check all channels.
   600 */
   601 extern DECLSPEC int SDLCALL Mix_Playing(int channel);
   602 extern DECLSPEC int SDLCALL Mix_PlayingMusic(void);
   603 
   604 /* Stop music and set external music playback command */
   605 extern DECLSPEC int SDLCALL Mix_SetMusicCMD(const char *command);
   606 
   607 /* Synchro value is set by MikMod from modules while playing */
   608 extern DECLSPEC int SDLCALL Mix_SetSynchroValue(int value);
   609 extern DECLSPEC int SDLCALL Mix_GetSynchroValue(void);
   610 
   611 /* Set/Get/Iterate SoundFonts paths to use by supported MIDI backends */
   612 extern DECLSPEC int SDLCALL Mix_SetSoundFonts(const char *paths);
   613 extern DECLSPEC const char* SDLCALL Mix_GetSoundFonts(void);
   614 extern DECLSPEC int SDLCALL Mix_EachSoundFont(int (*function)(const char*, void*), void *data);
   615 
   616 /* Get the Mix_Chunk currently associated with a mixer channel
   617     Returns NULL if it's an invalid channel, or there's no chunk associated.
   618 */
   619 extern DECLSPEC Mix_Chunk * SDLCALL Mix_GetChunk(int channel);
   620 
   621 /* Close the mixer, halting all playing audio */
   622 extern DECLSPEC void SDLCALL Mix_CloseAudio(void);
   623 
   624 /* We'll use SDL for reporting errors */
   625 #define Mix_SetError    SDL_SetError
   626 #define Mix_GetError    SDL_GetError
   627 
   628 /* Ends C function definitions when using C++ */
   629 #ifdef __cplusplus
   630 }
   631 #endif
   632 #include "close_code.h"
   633 
   634 #endif /* _SDL_MIXER_H */