include/SDL_audio.h
author Sam Lantinga <slouken@libsdl.org>
Sun, 22 Jan 2012 17:26:45 -0500
changeset 6251 3e8c673cad58
parent 6138 4c64952a58fb
child 6885 700f1b25f77f
permissions -rw-r--r--
Removing some more references to SDL 1.3
     1 /*
     2   Simple DirectMedia Layer
     3   Copyright (C) 1997-2012 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 /**
    23  *  \file SDL_audio.h
    24  *  
    25  *  Access to the raw audio mixing buffer for the SDL library.
    26  */
    27 
    28 #ifndef _SDL_audio_h
    29 #define _SDL_audio_h
    30 
    31 #include "SDL_stdinc.h"
    32 #include "SDL_error.h"
    33 #include "SDL_endian.h"
    34 #include "SDL_mutex.h"
    35 #include "SDL_thread.h"
    36 #include "SDL_rwops.h"
    37 
    38 #include "begin_code.h"
    39 /* Set up for C function definitions, even when using C++ */
    40 #ifdef __cplusplus
    41 /* *INDENT-OFF* */
    42 extern "C" {
    43 /* *INDENT-ON* */
    44 #endif
    45 
    46 /**
    47  *  \brief Audio format flags.
    48  *  
    49  *  These are what the 16 bits in SDL_AudioFormat currently mean...
    50  *  (Unspecified bits are always zero).
    51  *  
    52  *  \verbatim
    53     ++-----------------------sample is signed if set
    54     ||
    55     ||       ++-----------sample is bigendian if set
    56     ||       ||
    57     ||       ||          ++---sample is float if set
    58     ||       ||          ||
    59     ||       ||          || +---sample bit size---+
    60     ||       ||          || |                     |
    61     15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00
    62     \endverbatim
    63  *  
    64  *  There are macros in SDL 2.0 and later to query these bits.
    65  */
    66 typedef Uint16 SDL_AudioFormat;
    67 
    68 /**
    69  *  \name Audio flags
    70  */
    71 /*@{*/
    72 
    73 #define SDL_AUDIO_MASK_BITSIZE       (0xFF)
    74 #define SDL_AUDIO_MASK_DATATYPE      (1<<8)
    75 #define SDL_AUDIO_MASK_ENDIAN        (1<<12)
    76 #define SDL_AUDIO_MASK_SIGNED        (1<<15)
    77 #define SDL_AUDIO_BITSIZE(x)         (x & SDL_AUDIO_MASK_BITSIZE)
    78 #define SDL_AUDIO_ISFLOAT(x)         (x & SDL_AUDIO_MASK_DATATYPE)
    79 #define SDL_AUDIO_ISBIGENDIAN(x)     (x & SDL_AUDIO_MASK_ENDIAN)
    80 #define SDL_AUDIO_ISSIGNED(x)        (x & SDL_AUDIO_MASK_SIGNED)
    81 #define SDL_AUDIO_ISINT(x)           (!SDL_AUDIO_ISFLOAT(x))
    82 #define SDL_AUDIO_ISLITTLEENDIAN(x)  (!SDL_AUDIO_ISBIGENDIAN(x))
    83 #define SDL_AUDIO_ISUNSIGNED(x)      (!SDL_AUDIO_ISSIGNED(x))
    84 
    85 /** 
    86  *  \name Audio format flags
    87  *
    88  *  Defaults to LSB byte order.
    89  */
    90 /*@{*/
    91 #define AUDIO_U8	0x0008  /**< Unsigned 8-bit samples */
    92 #define AUDIO_S8	0x8008  /**< Signed 8-bit samples */
    93 #define AUDIO_U16LSB	0x0010  /**< Unsigned 16-bit samples */
    94 #define AUDIO_S16LSB	0x8010  /**< Signed 16-bit samples */
    95 #define AUDIO_U16MSB	0x1010  /**< As above, but big-endian byte order */
    96 #define AUDIO_S16MSB	0x9010  /**< As above, but big-endian byte order */
    97 #define AUDIO_U16	AUDIO_U16LSB
    98 #define AUDIO_S16	AUDIO_S16LSB
    99 /*@}*/
   100 
   101 /**
   102  *  \name int32 support
   103  *  
   104  *  New to SDL 1.3.
   105  */
   106 /*@{*/
   107 #define AUDIO_S32LSB	0x8020  /**< 32-bit integer samples */
   108 #define AUDIO_S32MSB	0x9020  /**< As above, but big-endian byte order */
   109 #define AUDIO_S32	AUDIO_S32LSB
   110 /*@}*/
   111 
   112 /**
   113  *  \name float32 support
   114  *  
   115  *  New to SDL 1.3.
   116  */
   117 /*@{*/
   118 #define AUDIO_F32LSB	0x8120  /**< 32-bit floating point samples */
   119 #define AUDIO_F32MSB	0x9120  /**< As above, but big-endian byte order */
   120 #define AUDIO_F32	AUDIO_F32LSB
   121 /*@}*/
   122 
   123 /**
   124  *  \name Native audio byte ordering
   125  */
   126 /*@{*/
   127 #if SDL_BYTEORDER == SDL_LIL_ENDIAN
   128 #define AUDIO_U16SYS	AUDIO_U16LSB
   129 #define AUDIO_S16SYS	AUDIO_S16LSB
   130 #define AUDIO_S32SYS	AUDIO_S32LSB
   131 #define AUDIO_F32SYS	AUDIO_F32LSB
   132 #else
   133 #define AUDIO_U16SYS	AUDIO_U16MSB
   134 #define AUDIO_S16SYS	AUDIO_S16MSB
   135 #define AUDIO_S32SYS	AUDIO_S32MSB
   136 #define AUDIO_F32SYS	AUDIO_F32MSB
   137 #endif
   138 /*@}*/
   139 
   140 /** 
   141  *  \name Allow change flags
   142  *  
   143  *  Which audio format changes are allowed when opening a device.
   144  */
   145 /*@{*/
   146 #define SDL_AUDIO_ALLOW_FREQUENCY_CHANGE    0x00000001
   147 #define SDL_AUDIO_ALLOW_FORMAT_CHANGE       0x00000002
   148 #define SDL_AUDIO_ALLOW_CHANNELS_CHANGE     0x00000004
   149 #define SDL_AUDIO_ALLOW_ANY_CHANGE          (SDL_AUDIO_ALLOW_FREQUENCY_CHANGE|SDL_AUDIO_ALLOW_FORMAT_CHANGE|SDL_AUDIO_ALLOW_CHANNELS_CHANGE)
   150 /*@}*/
   151 
   152 /*@}*//*Audio flags*/
   153 
   154 /**
   155  *  This function is called when the audio device needs more data.
   156  *
   157  *  \param userdata An application-specific parameter saved in
   158  *                  the SDL_AudioSpec structure
   159  *  \param stream A pointer to the audio data buffer.
   160  *  \param len    The length of that buffer in bytes.
   161  *
   162  *  Once the callback returns, the buffer will no longer be valid.
   163  *  Stereo samples are stored in a LRLRLR ordering.
   164  */
   165 typedef void (SDLCALL * SDL_AudioCallback) (void *userdata, Uint8 * stream,
   166                                             int len);
   167 
   168 /**
   169  *  The calculated values in this structure are calculated by SDL_OpenAudio().
   170  */
   171 typedef struct SDL_AudioSpec
   172 {
   173     int freq;                   /**< DSP frequency -- samples per second */
   174     SDL_AudioFormat format;     /**< Audio data format */
   175     Uint8 channels;             /**< Number of channels: 1 mono, 2 stereo */
   176     Uint8 silence;              /**< Audio buffer silence value (calculated) */
   177     Uint16 samples;             /**< Audio buffer size in samples (power of 2) */
   178     Uint16 padding;             /**< Necessary for some compile environments */
   179     Uint32 size;                /**< Audio buffer size in bytes (calculated) */
   180     SDL_AudioCallback callback;
   181     void *userdata;
   182 } SDL_AudioSpec;
   183 
   184 
   185 struct SDL_AudioCVT;
   186 typedef void (SDLCALL * SDL_AudioFilter) (struct SDL_AudioCVT * cvt,
   187                                           SDL_AudioFormat format);
   188 
   189 /**
   190  *  A structure to hold a set of audio conversion filters and buffers.
   191  */
   192 typedef struct SDL_AudioCVT
   193 {
   194     int needed;                 /**< Set to 1 if conversion possible */
   195     SDL_AudioFormat src_format; /**< Source audio format */
   196     SDL_AudioFormat dst_format; /**< Target audio format */
   197     double rate_incr;           /**< Rate conversion increment */
   198     Uint8 *buf;                 /**< Buffer to hold entire audio data */
   199     int len;                    /**< Length of original audio buffer */
   200     int len_cvt;                /**< Length of converted audio buffer */
   201     int len_mult;               /**< buffer must be len*len_mult big */
   202     double len_ratio;           /**< Given len, final size is len*len_ratio */
   203     SDL_AudioFilter filters[10];        /**< Filter list */
   204     int filter_index;           /**< Current audio conversion function */
   205 } SDL_AudioCVT;
   206 
   207 
   208 /* Function prototypes */
   209 
   210 /**
   211  *  \name Driver discovery functions
   212  *  
   213  *  These functions return the list of built in audio drivers, in the
   214  *  order that they are normally initialized by default.
   215  */
   216 /*@{*/
   217 extern DECLSPEC int SDLCALL SDL_GetNumAudioDrivers(void);
   218 extern DECLSPEC const char *SDLCALL SDL_GetAudioDriver(int index);
   219 /*@}*/
   220 
   221 /**
   222  *  \name Initialization and cleanup
   223  *  
   224  *  \internal These functions are used internally, and should not be used unless
   225  *            you have a specific need to specify the audio driver you want to 
   226  *            use.  You should normally use SDL_Init() or SDL_InitSubSystem().
   227  */
   228 /*@{*/
   229 extern DECLSPEC int SDLCALL SDL_AudioInit(const char *driver_name);
   230 extern DECLSPEC void SDLCALL SDL_AudioQuit(void);
   231 /*@}*/
   232 
   233 /**
   234  *  This function returns the name of the current audio driver, or NULL
   235  *  if no driver has been initialized.
   236  */
   237 extern DECLSPEC const char *SDLCALL SDL_GetCurrentAudioDriver(void);
   238 
   239 /**
   240  *  This function opens the audio device with the desired parameters, and
   241  *  returns 0 if successful, placing the actual hardware parameters in the
   242  *  structure pointed to by \c obtained.  If \c obtained is NULL, the audio
   243  *  data passed to the callback function will be guaranteed to be in the
   244  *  requested format, and will be automatically converted to the hardware
   245  *  audio format if necessary.  This function returns -1 if it failed 
   246  *  to open the audio device, or couldn't set up the audio thread.
   247  *  
   248  *  When filling in the desired audio spec structure,
   249  *    - \c desired->freq should be the desired audio frequency in samples-per-
   250  *      second.
   251  *    - \c desired->format should be the desired audio format.
   252  *    - \c desired->samples is the desired size of the audio buffer, in 
   253  *      samples.  This number should be a power of two, and may be adjusted by 
   254  *      the audio driver to a value more suitable for the hardware.  Good values
   255  *      seem to range between 512 and 8096 inclusive, depending on the 
   256  *      application and CPU speed.  Smaller values yield faster response time, 
   257  *      but can lead to underflow if the application is doing heavy processing 
   258  *      and cannot fill the audio buffer in time.  A stereo sample consists of 
   259  *      both right and left channels in LR ordering.
   260  *      Note that the number of samples is directly related to time by the
   261  *      following formula:  \code ms = (samples*1000)/freq \endcode
   262  *    - \c desired->size is the size in bytes of the audio buffer, and is
   263  *      calculated by SDL_OpenAudio().
   264  *    - \c desired->silence is the value used to set the buffer to silence,
   265  *      and is calculated by SDL_OpenAudio().
   266  *    - \c desired->callback should be set to a function that will be called
   267  *      when the audio device is ready for more data.  It is passed a pointer
   268  *      to the audio buffer, and the length in bytes of the audio buffer.
   269  *      This function usually runs in a separate thread, and so you should
   270  *      protect data structures that it accesses by calling SDL_LockAudio()
   271  *      and SDL_UnlockAudio() in your code.
   272  *    - \c desired->userdata is passed as the first parameter to your callback
   273  *      function.
   274  *  
   275  *  The audio device starts out playing silence when it's opened, and should
   276  *  be enabled for playing by calling \c SDL_PauseAudio(0) when you are ready
   277  *  for your audio callback function to be called.  Since the audio driver
   278  *  may modify the requested size of the audio buffer, you should allocate
   279  *  any local mixing buffers after you open the audio device.
   280  */
   281 extern DECLSPEC int SDLCALL SDL_OpenAudio(SDL_AudioSpec * desired,
   282                                           SDL_AudioSpec * obtained);
   283 
   284 /**
   285  *  SDL Audio Device IDs.
   286  *  
   287  *  A successful call to SDL_OpenAudio() is always device id 1, and legacy
   288  *  SDL audio APIs assume you want this device ID. SDL_OpenAudioDevice() calls
   289  *  always returns devices >= 2 on success. The legacy calls are good both
   290  *  for backwards compatibility and when you don't care about multiple,
   291  *  specific, or capture devices.
   292  */
   293 typedef Uint32 SDL_AudioDeviceID;
   294 
   295 /**
   296  *  Get the number of available devices exposed by the current driver.
   297  *  Only valid after a successfully initializing the audio subsystem.
   298  *  Returns -1 if an explicit list of devices can't be determined; this is
   299  *  not an error. For example, if SDL is set up to talk to a remote audio
   300  *  server, it can't list every one available on the Internet, but it will
   301  *  still allow a specific host to be specified to SDL_OpenAudioDevice().
   302  *  
   303  *  In many common cases, when this function returns a value <= 0, it can still
   304  *  successfully open the default device (NULL for first argument of
   305  *  SDL_OpenAudioDevice()).
   306  */
   307 extern DECLSPEC int SDLCALL SDL_GetNumAudioDevices(int iscapture);
   308 
   309 /**
   310  *  Get the human-readable name of a specific audio device.
   311  *  Must be a value between 0 and (number of audio devices-1).
   312  *  Only valid after a successfully initializing the audio subsystem.
   313  *  The values returned by this function reflect the latest call to
   314  *  SDL_GetNumAudioDevices(); recall that function to redetect available
   315  *  hardware.
   316  *  
   317  *  The string returned by this function is UTF-8 encoded, read-only, and
   318  *  managed internally. You are not to free it. If you need to keep the
   319  *  string for any length of time, you should make your own copy of it, as it
   320  *  will be invalid next time any of several other SDL functions is called.
   321  */
   322 extern DECLSPEC const char *SDLCALL SDL_GetAudioDeviceName(int index,
   323                                                            int iscapture);
   324 
   325 
   326 /**
   327  *  Open a specific audio device. Passing in a device name of NULL requests
   328  *  the most reasonable default (and is equivalent to calling SDL_OpenAudio()).
   329  *  
   330  *  The device name is a UTF-8 string reported by SDL_GetAudioDeviceName(), but
   331  *  some drivers allow arbitrary and driver-specific strings, such as a
   332  *  hostname/IP address for a remote audio server, or a filename in the
   333  *  diskaudio driver.
   334  *  
   335  *  \return 0 on error, a valid device ID that is >= 2 on success.
   336  *  
   337  *  SDL_OpenAudio(), unlike this function, always acts on device ID 1.
   338  */
   339 extern DECLSPEC SDL_AudioDeviceID SDLCALL SDL_OpenAudioDevice(const char
   340                                                               *device,
   341                                                               int iscapture,
   342                                                               const
   343                                                               SDL_AudioSpec *
   344                                                               desired,
   345                                                               SDL_AudioSpec *
   346                                                               obtained,
   347                                                               int
   348                                                               allowed_changes);
   349 
   350 
   351 
   352 /**
   353  *  \name Audio state
   354  *  
   355  *  Get the current audio state.
   356  */
   357 /*@{*/
   358 typedef enum
   359 {
   360     SDL_AUDIO_STOPPED = 0,
   361     SDL_AUDIO_PLAYING,
   362     SDL_AUDIO_PAUSED
   363 } SDL_AudioStatus;
   364 extern DECLSPEC SDL_AudioStatus SDLCALL SDL_GetAudioStatus(void);
   365 
   366 extern DECLSPEC SDL_AudioStatus SDLCALL
   367 SDL_GetAudioDeviceStatus(SDL_AudioDeviceID dev);
   368 /*@}*//*Audio State*/
   369 
   370 /**
   371  *  \name Pause audio functions
   372  *  
   373  *  These functions pause and unpause the audio callback processing.
   374  *  They should be called with a parameter of 0 after opening the audio
   375  *  device to start playing sound.  This is so you can safely initialize
   376  *  data for your callback function after opening the audio device.
   377  *  Silence will be written to the audio device during the pause.
   378  */
   379 /*@{*/
   380 extern DECLSPEC void SDLCALL SDL_PauseAudio(int pause_on);
   381 extern DECLSPEC void SDLCALL SDL_PauseAudioDevice(SDL_AudioDeviceID dev,
   382                                                   int pause_on);
   383 /*@}*//*Pause audio functions*/
   384 
   385 /**
   386  *  This function loads a WAVE from the data source, automatically freeing
   387  *  that source if \c freesrc is non-zero.  For example, to load a WAVE file,
   388  *  you could do:
   389  *  \code
   390  *  	SDL_LoadWAV_RW(SDL_RWFromFile("sample.wav", "rb"), 1, ...);
   391  *  \endcode
   392  *
   393  *  If this function succeeds, it returns the given SDL_AudioSpec,
   394  *  filled with the audio data format of the wave data, and sets
   395  *  \c *audio_buf to a malloc()'d buffer containing the audio data,
   396  *  and sets \c *audio_len to the length of that audio buffer, in bytes.
   397  *  You need to free the audio buffer with SDL_FreeWAV() when you are 
   398  *  done with it.
   399  *
   400  *  This function returns NULL and sets the SDL error message if the 
   401  *  wave file cannot be opened, uses an unknown data format, or is 
   402  *  corrupt.  Currently raw and MS-ADPCM WAVE files are supported.
   403  */
   404 extern DECLSPEC SDL_AudioSpec *SDLCALL SDL_LoadWAV_RW(SDL_RWops * src,
   405                                                       int freesrc,
   406                                                       SDL_AudioSpec * spec,
   407                                                       Uint8 ** audio_buf,
   408                                                       Uint32 * audio_len);
   409 
   410 /** 
   411  *  Loads a WAV from a file.
   412  *  Compatibility convenience function.
   413  */
   414 #define SDL_LoadWAV(file, spec, audio_buf, audio_len) \
   415 	SDL_LoadWAV_RW(SDL_RWFromFile(file, "rb"),1, spec,audio_buf,audio_len)
   416 
   417 /**
   418  *  This function frees data previously allocated with SDL_LoadWAV_RW()
   419  */
   420 extern DECLSPEC void SDLCALL SDL_FreeWAV(Uint8 * audio_buf);
   421 
   422 /**
   423  *  This function takes a source format and rate and a destination format
   424  *  and rate, and initializes the \c cvt structure with information needed
   425  *  by SDL_ConvertAudio() to convert a buffer of audio data from one format
   426  *  to the other.
   427  *  
   428  *  \return -1 if the format conversion is not supported, 0 if there's
   429  *  no conversion needed, or 1 if the audio filter is set up.
   430  */
   431 extern DECLSPEC int SDLCALL SDL_BuildAudioCVT(SDL_AudioCVT * cvt,
   432                                               SDL_AudioFormat src_format,
   433                                               Uint8 src_channels,
   434                                               int src_rate,
   435                                               SDL_AudioFormat dst_format,
   436                                               Uint8 dst_channels,
   437                                               int dst_rate);
   438 
   439 /**
   440  *  Once you have initialized the \c cvt structure using SDL_BuildAudioCVT(),
   441  *  created an audio buffer \c cvt->buf, and filled it with \c cvt->len bytes of
   442  *  audio data in the source format, this function will convert it in-place
   443  *  to the desired format.
   444  *  
   445  *  The data conversion may expand the size of the audio data, so the buffer
   446  *  \c cvt->buf should be allocated after the \c cvt structure is initialized by
   447  *  SDL_BuildAudioCVT(), and should be \c cvt->len*cvt->len_mult bytes long.
   448  */
   449 extern DECLSPEC int SDLCALL SDL_ConvertAudio(SDL_AudioCVT * cvt);
   450 
   451 #define SDL_MIX_MAXVOLUME 128
   452 /**
   453  *  This takes two audio buffers of the playing audio format and mixes
   454  *  them, performing addition, volume adjustment, and overflow clipping.
   455  *  The volume ranges from 0 - 128, and should be set to ::SDL_MIX_MAXVOLUME
   456  *  for full audio volume.  Note this does not change hardware volume.
   457  *  This is provided for convenience -- you can mix your own audio data.
   458  */
   459 extern DECLSPEC void SDLCALL SDL_MixAudio(Uint8 * dst, const Uint8 * src,
   460                                           Uint32 len, int volume);
   461 
   462 /**
   463  *  This works like SDL_MixAudio(), but you specify the audio format instead of
   464  *  using the format of audio device 1. Thus it can be used when no audio
   465  *  device is open at all.
   466  */
   467 extern DECLSPEC void SDLCALL SDL_MixAudioFormat(Uint8 * dst,
   468                                                 const Uint8 * src,
   469                                                 SDL_AudioFormat format,
   470                                                 Uint32 len, int volume);
   471 
   472 /**
   473  *  \name Audio lock functions
   474  *  
   475  *  The lock manipulated by these functions protects the callback function.
   476  *  During a SDL_LockAudio()/SDL_UnlockAudio() pair, you can be guaranteed that 
   477  *  the callback function is not running.  Do not call these from the callback
   478  *  function or you will cause deadlock.
   479  */
   480 /*@{*/
   481 extern DECLSPEC void SDLCALL SDL_LockAudio(void);
   482 extern DECLSPEC void SDLCALL SDL_LockAudioDevice(SDL_AudioDeviceID dev);
   483 extern DECLSPEC void SDLCALL SDL_UnlockAudio(void);
   484 extern DECLSPEC void SDLCALL SDL_UnlockAudioDevice(SDL_AudioDeviceID dev);
   485 /*@}*//*Audio lock functions*/
   486 
   487 /**
   488  *  This function shuts down audio processing and closes the audio device.
   489  */
   490 extern DECLSPEC void SDLCALL SDL_CloseAudio(void);
   491 extern DECLSPEC void SDLCALL SDL_CloseAudioDevice(SDL_AudioDeviceID dev);
   492 
   493 /**
   494  * \return 1 if audio device is still functioning, zero if not, -1 on error.
   495  */
   496 extern DECLSPEC int SDLCALL SDL_AudioDeviceConnected(SDL_AudioDeviceID dev);
   497 
   498 
   499 /* Ends C function definitions when using C++ */
   500 #ifdef __cplusplus
   501 /* *INDENT-OFF* */
   502 }
   503 /* *INDENT-ON* */
   504 #endif
   505 #include "close_code.h"
   506 
   507 #endif /* _SDL_audio_h */
   508 
   509 /* vi: set ts=4 sw=4 expandtab: */