include/SDL_audio.h
author Sam Lantinga <slouken@libsdl.org>
Sun, 24 Jan 2010 21:10:53 +0000
changeset 3697 f7b03b6838cb
parent 3554 cf815007e443
child 5262 b530ef003506
permissions -rw-r--r--
Fixed bug #926

Updated copyright to LGPL version 2.1 and year 2010
     1 /*
     2     SDL - Simple DirectMedia Layer
     3     Copyright (C) 1997-2010 Sam Lantinga
     4 
     5     This library is free software; you can redistribute it and/or
     6     modify it under the terms of the GNU Lesser General Public
     7     License as published by the Free Software Foundation; either
     8     version 2.1 of the License, or (at your option) any later version.
     9 
    10     This library is distributed in the hope that it will be useful,
    11     but WITHOUT ANY WARRANTY; without even the implied warranty of
    12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    13     Lesser General Public License for more details.
    14 
    15     You should have received a copy of the GNU Lesser General Public
    16     License along with this library; if not, write to the Free Software
    17     Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
    18 
    19     Sam Lantinga
    20     slouken@libsdl.org
    21 */
    22 
    23 /**
    24  *  \file SDL_audio.h
    25  *  
    26  *  Access to the raw audio mixing buffer for the SDL library.
    27  */
    28 
    29 #ifndef _SDL_audio_h
    30 #define _SDL_audio_h
    31 
    32 #include "SDL_stdinc.h"
    33 #include "SDL_error.h"
    34 #include "SDL_endian.h"
    35 #include "SDL_mutex.h"
    36 #include "SDL_thread.h"
    37 #include "SDL_rwops.h"
    38 
    39 #include "begin_code.h"
    40 /* Set up for C function definitions, even when using C++ */
    41 #ifdef __cplusplus
    42 /* *INDENT-OFF* */
    43 extern "C" {
    44 /* *INDENT-ON* */
    45 #endif
    46 
    47 /**
    48  *  \brief Audio format flags.
    49  *  
    50  *  These are what the 16 bits in SDL_AudioFormat currently mean...
    51  *  (Unspecified bits are always zero).
    52  *  
    53  *  \verbatim
    54     ++-----------------------sample is signed if set
    55     ||
    56     ||       ++-----------sample is bigendian if set
    57     ||       ||
    58     ||       ||          ++---sample is float if set
    59     ||       ||          ||
    60     ||       ||          || +---sample bit size---+
    61     ||       ||          || |                     |
    62     15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00
    63     \endverbatim
    64  *  
    65  *  There are macros in SDL 1.3 and later to query these bits.
    66  */
    67 typedef Uint16 SDL_AudioFormat;
    68 
    69 /**
    70  *  \name Audio flags
    71  */
    72 /*@{*/
    73 
    74 #define SDL_AUDIO_MASK_BITSIZE       (0xFF)
    75 #define SDL_AUDIO_MASK_DATATYPE      (1<<8)
    76 #define SDL_AUDIO_MASK_ENDIAN        (1<<12)
    77 #define SDL_AUDIO_MASK_SIGNED        (1<<15)
    78 #define SDL_AUDIO_BITSIZE(x)         (x & SDL_AUDIO_MASK_BITSIZE)
    79 #define SDL_AUDIO_ISFLOAT(x)         (x & SDL_AUDIO_MASK_DATATYPE)
    80 #define SDL_AUDIO_ISBIGENDIAN(x)     (x & SDL_AUDIO_MASK_ENDIAN)
    81 #define SDL_AUDIO_ISSIGNED(x)        (x & SDL_AUDIO_MASK_SIGNED)
    82 #define SDL_AUDIO_ISINT(x)           (!SDL_AUDIO_ISFLOAT(x))
    83 #define SDL_AUDIO_ISLITTLEENDIAN(x)  (!SDL_AUDIO_ISBIGENDIAN(x))
    84 #define SDL_AUDIO_ISUNSIGNED(x)      (!SDL_AUDIO_ISSIGNED(x))
    85 
    86 /** 
    87  *  \name Audio format flags
    88  *
    89  *  Defaults to LSB byte order.
    90  */
    91 /*@{*/
    92 #define AUDIO_U8	0x0008  /**< Unsigned 8-bit samples */
    93 #define AUDIO_S8	0x8008  /**< Signed 8-bit samples */
    94 #define AUDIO_U16LSB	0x0010  /**< Unsigned 16-bit samples */
    95 #define AUDIO_S16LSB	0x8010  /**< Signed 16-bit samples */
    96 #define AUDIO_U16MSB	0x1010  /**< As above, but big-endian byte order */
    97 #define AUDIO_S16MSB	0x9010  /**< As above, but big-endian byte order */
    98 #define AUDIO_U16	AUDIO_U16LSB
    99 #define AUDIO_S16	AUDIO_S16LSB
   100 /*@}*/
   101 
   102 /**
   103  *  \name int32 support
   104  *  
   105  *  New to SDL 1.3.
   106  */
   107 /*@{*/
   108 #define AUDIO_S32LSB	0x8020  /**< 32-bit integer samples */
   109 #define AUDIO_S32MSB	0x9020  /**< As above, but big-endian byte order */
   110 #define AUDIO_S32	AUDIO_S32LSB
   111 /*@}*/
   112 
   113 /**
   114  *  \name float32 support
   115  *  
   116  *  New to SDL 1.3.
   117  */
   118 /*@{*/
   119 #define AUDIO_F32LSB	0x8120  /**< 32-bit floating point samples */
   120 #define AUDIO_F32MSB	0x9120  /**< As above, but big-endian byte order */
   121 #define AUDIO_F32	AUDIO_F32LSB
   122 /*@}*/
   123 
   124 /**
   125  *  \name Native audio byte ordering
   126  */
   127 /*@{*/
   128 #if SDL_BYTEORDER == SDL_LIL_ENDIAN
   129 #define AUDIO_U16SYS	AUDIO_U16LSB
   130 #define AUDIO_S16SYS	AUDIO_S16LSB
   131 #define AUDIO_S32SYS	AUDIO_S32LSB
   132 #define AUDIO_F32SYS	AUDIO_F32LSB
   133 #else
   134 #define AUDIO_U16SYS	AUDIO_U16MSB
   135 #define AUDIO_S16SYS	AUDIO_S16MSB
   136 #define AUDIO_S32SYS	AUDIO_S32MSB
   137 #define AUDIO_F32SYS	AUDIO_F32MSB
   138 #endif
   139 /*@}*/
   140 
   141 /** 
   142  *  \name Allow change flags
   143  *  
   144  *  Which audio format changes are allowed when opening a device.
   145  */
   146 /*@{*/
   147 #define SDL_AUDIO_ALLOW_FREQUENCY_CHANGE    0x00000001
   148 #define SDL_AUDIO_ALLOW_FORMAT_CHANGE       0x00000002
   149 #define SDL_AUDIO_ALLOW_CHANNELS_CHANGE     0x00000004
   150 #define SDL_AUDIO_ALLOW_ANY_CHANGE          (SDL_AUDIO_ALLOW_FREQUENCY_CHANGE|SDL_AUDIO_ALLOW_FORMAT_CHANGE|SDL_AUDIO_ALLOW_CHANNELS_CHANGE)
   151 /*@}*/
   152 
   153 /*@}*//*Audio flags*/
   154 
   155 /**
   156  *  This function is called when the audio device needs more data.
   157  *
   158  *  \param userdata An application-specific parameter saved in
   159  *                  the SDL_AudioSpec structure
   160  *  \param stream A pointer to the audio data buffer.
   161  *  \param len    The length of that buffer in bytes.
   162  *
   163  *  Once the callback returns, the buffer will no longer be valid.
   164  *  Stereo samples are stored in a LRLRLR ordering.
   165  */
   166 typedef void (SDLCALL * SDL_AudioCallback) (void *userdata, Uint8 * stream,
   167                                             int len);
   168 
   169 /**
   170  *  The calculated values in this structure are calculated by SDL_OpenAudio().
   171  */
   172 typedef struct SDL_AudioSpec
   173 {
   174     int freq;                   /**< DSP frequency -- samples per second */
   175     SDL_AudioFormat format;     /**< Audio data format */
   176     Uint8 channels;             /**< Number of channels: 1 mono, 2 stereo */
   177     Uint8 silence;              /**< Audio buffer silence value (calculated) */
   178     Uint16 samples;             /**< Audio buffer size in samples (power of 2) */
   179     Uint16 padding;             /**< Necessary for some compile environments */
   180     Uint32 size;                /**< Audio buffer size in bytes (calculated) */
   181     SDL_AudioCallback callback;
   182     void *userdata;
   183 } SDL_AudioSpec;
   184 
   185 
   186 struct SDL_AudioCVT;
   187 typedef void (SDLCALL * SDL_AudioFilter) (struct SDL_AudioCVT * cvt,
   188                                           SDL_AudioFormat format);
   189 
   190 /**
   191  *  A structure to hold a set of audio conversion filters and buffers.
   192  */
   193 typedef struct SDL_AudioCVT
   194 {
   195     int needed;                 /**< Set to 1 if conversion possible */
   196     SDL_AudioFormat src_format; /**< Source audio format */
   197     SDL_AudioFormat dst_format; /**< Target audio format */
   198     double rate_incr;           /**< Rate conversion increment */
   199     Uint8 *buf;                 /**< Buffer to hold entire audio data */
   200     int len;                    /**< Length of original audio buffer */
   201     int len_cvt;                /**< Length of converted audio buffer */
   202     int len_mult;               /**< buffer must be len*len_mult big */
   203     double len_ratio;           /**< Given len, final size is len*len_ratio */
   204     SDL_AudioFilter filters[10];        /**< Filter list */
   205     int filter_index;           /**< Current audio conversion function */
   206 } SDL_AudioCVT;
   207 
   208 
   209 /* Function prototypes */
   210 
   211 /**
   212  *  \name Driver discovery functions
   213  *  
   214  *  These functions return the list of built in audio drivers, in the
   215  *  order that they are normally initialized by default.
   216  */
   217 /*@{*/
   218 extern DECLSPEC int SDLCALL SDL_GetNumAudioDrivers(void);
   219 extern DECLSPEC const char *SDLCALL SDL_GetAudioDriver(int index);
   220 /*@}*/
   221 
   222 /**
   223  *  \name Initialization and cleanup
   224  *  
   225  *  \internal These functions are used internally, and should not be used unless
   226  *            you have a specific need to specify the audio driver you want to 
   227  *            use.  You should normally use SDL_Init() or SDL_InitSubSystem().
   228  */
   229 /*@{*/
   230 extern DECLSPEC int SDLCALL SDL_AudioInit(const char *driver_name);
   231 extern DECLSPEC void SDLCALL SDL_AudioQuit(void);
   232 /*@}*/
   233 
   234 /**
   235  *  This function returns the name of the current audio driver, or NULL
   236  *  if no driver has been initialized.
   237  */
   238 extern DECLSPEC const char *SDLCALL SDL_GetCurrentAudioDriver(void);
   239 
   240 /**
   241  *  This function opens the audio device with the desired parameters, and
   242  *  returns 0 if successful, placing the actual hardware parameters in the
   243  *  structure pointed to by \c obtained.  If \c obtained is NULL, the audio
   244  *  data passed to the callback function will be guaranteed to be in the
   245  *  requested format, and will be automatically converted to the hardware
   246  *  audio format if necessary.  This function returns -1 if it failed 
   247  *  to open the audio device, or couldn't set up the audio thread.
   248  *  
   249  *  When filling in the desired audio spec structure,
   250  *    - \c desired->freq should be the desired audio frequency in samples-per-
   251  *      second.
   252  *    - \c desired->format should be the desired audio format.
   253  *    - \c desired->samples is the desired size of the audio buffer, in 
   254  *      samples.  This number should be a power of two, and may be adjusted by 
   255  *      the audio driver to a value more suitable for the hardware.  Good values
   256  *      seem to range between 512 and 8096 inclusive, depending on the 
   257  *      application and CPU speed.  Smaller values yield faster response time, 
   258  *      but can lead to underflow if the application is doing heavy processing 
   259  *      and cannot fill the audio buffer in time.  A stereo sample consists of 
   260  *      both right and left channels in LR ordering.
   261  *      Note that the number of samples is directly related to time by the
   262  *      following formula:  \code ms = (samples*1000)/freq \endcode
   263  *    - \c desired->size is the size in bytes of the audio buffer, and is
   264  *      calculated by SDL_OpenAudio().
   265  *    - \c desired->silence is the value used to set the buffer to silence,
   266  *      and is calculated by SDL_OpenAudio().
   267  *    - \c desired->callback should be set to a function that will be called
   268  *      when the audio device is ready for more data.  It is passed a pointer
   269  *      to the audio buffer, and the length in bytes of the audio buffer.
   270  *      This function usually runs in a separate thread, and so you should
   271  *      protect data structures that it accesses by calling SDL_LockAudio()
   272  *      and SDL_UnlockAudio() in your code.
   273  *    - \c desired->userdata is passed as the first parameter to your callback
   274  *      function.
   275  *  
   276  *  The audio device starts out playing silence when it's opened, and should
   277  *  be enabled for playing by calling \c SDL_PauseAudio(0) when you are ready
   278  *  for your audio callback function to be called.  Since the audio driver
   279  *  may modify the requested size of the audio buffer, you should allocate
   280  *  any local mixing buffers after you open the audio device.
   281  */
   282 extern DECLSPEC int SDLCALL SDL_OpenAudio(SDL_AudioSpec * desired,
   283                                           SDL_AudioSpec * obtained);
   284 
   285 /**
   286  *  SDL Audio Device IDs.
   287  *  
   288  *  A successful call to SDL_OpenAudio() is always device id 1, and legacy
   289  *  SDL audio APIs assume you want this device ID. SDL_OpenAudioDevice() calls
   290  *  always returns devices >= 2 on success. The legacy calls are good both
   291  *  for backwards compatibility and when you don't care about multiple,
   292  *  specific, or capture devices.
   293  */
   294 typedef Uint32 SDL_AudioDeviceID;
   295 
   296 /**
   297  *  Get the number of available devices exposed by the current driver.
   298  *  Only valid after a successfully initializing the audio subsystem.
   299  *  Returns -1 if an explicit list of devices can't be determined; this is
   300  *  not an error. For example, if SDL is set up to talk to a remote audio
   301  *  server, it can't list every one available on the Internet, but it will
   302  *  still allow a specific host to be specified to SDL_OpenAudioDevice().
   303  *  
   304  *  In many common cases, when this function returns a value <= 0, it can still
   305  *  successfully open the default device (NULL for first argument of
   306  *  SDL_OpenAudioDevice()).
   307  */
   308 extern DECLSPEC int SDLCALL SDL_GetNumAudioDevices(int iscapture);
   309 
   310 /**
   311  *  Get the human-readable name of a specific audio device.
   312  *  Must be a value between 0 and (number of audio devices-1).
   313  *  Only valid after a successfully initializing the audio subsystem.
   314  *  The values returned by this function reflect the latest call to
   315  *  SDL_GetNumAudioDevices(); recall that function to redetect available
   316  *  hardware.
   317  *  
   318  *  The string returned by this function is UTF-8 encoded, read-only, and
   319  *  managed internally. You are not to free it. If you need to keep the
   320  *  string for any length of time, you should make your own copy of it, as it
   321  *  will be invalid next time any of several other SDL functions is called.
   322  */
   323 extern DECLSPEC const char *SDLCALL SDL_GetAudioDeviceName(int index,
   324                                                            int iscapture);
   325 
   326 
   327 /**
   328  *  Open a specific audio device. Passing in a device name of NULL requests
   329  *  the most reasonable default (and is equivalent to calling SDL_OpenAudio()).
   330  *  
   331  *  The device name is a UTF-8 string reported by SDL_GetAudioDeviceName(), but
   332  *  some drivers allow arbitrary and driver-specific strings, such as a
   333  *  hostname/IP address for a remote audio server, or a filename in the
   334  *  diskaudio driver.
   335  *  
   336  *  \return 0 on error, a valid device ID that is >= 2 on success.
   337  *  
   338  *  SDL_OpenAudio(), unlike this function, always acts on device ID 1.
   339  */
   340 extern DECLSPEC SDL_AudioDeviceID SDLCALL SDL_OpenAudioDevice(const char
   341                                                               *device,
   342                                                               int iscapture,
   343                                                               const
   344                                                               SDL_AudioSpec *
   345                                                               desired,
   346                                                               SDL_AudioSpec *
   347                                                               obtained,
   348                                                               int
   349                                                               allowed_changes);
   350 
   351 
   352 
   353 /**
   354  *  \name Audio state
   355  *  
   356  *  Get the current audio state.
   357  */
   358 /*@{*/
   359 typedef enum
   360 {
   361     SDL_AUDIO_STOPPED = 0,
   362     SDL_AUDIO_PLAYING,
   363     SDL_AUDIO_PAUSED
   364 } SDL_AudioStatus;
   365 extern DECLSPEC SDL_AudioStatus SDLCALL SDL_GetAudioStatus(void);
   366 
   367 extern DECLSPEC SDL_AudioStatus SDLCALL
   368 SDL_GetAudioDeviceStatus(SDL_AudioDeviceID dev);
   369 /*@}*//*Audio State*/
   370 
   371 /**
   372  *  \name Pause audio functions
   373  *  
   374  *  These functions pause and unpause the audio callback processing.
   375  *  They should be called with a parameter of 0 after opening the audio
   376  *  device to start playing sound.  This is so you can safely initialize
   377  *  data for your callback function after opening the audio device.
   378  *  Silence will be written to the audio device during the pause.
   379  */
   380 /*@{*/
   381 extern DECLSPEC void SDLCALL SDL_PauseAudio(int pause_on);
   382 extern DECLSPEC void SDLCALL SDL_PauseAudioDevice(SDL_AudioDeviceID dev,
   383                                                   int pause_on);
   384 /*@}*//*Pause audio functions*/
   385 
   386 /**
   387  *  This function loads a WAVE from the data source, automatically freeing
   388  *  that source if \c freesrc is non-zero.  For example, to load a WAVE file,
   389  *  you could do:
   390  *  \code
   391  *  	SDL_LoadWAV_RW(SDL_RWFromFile("sample.wav", "rb"), 1, ...);
   392  *  \endcode
   393  *
   394  *  If this function succeeds, it returns the given SDL_AudioSpec,
   395  *  filled with the audio data format of the wave data, and sets
   396  *  \c *audio_buf to a malloc()'d buffer containing the audio data,
   397  *  and sets \c *audio_len to the length of that audio buffer, in bytes.
   398  *  You need to free the audio buffer with SDL_FreeWAV() when you are 
   399  *  done with it.
   400  *
   401  *  This function returns NULL and sets the SDL error message if the 
   402  *  wave file cannot be opened, uses an unknown data format, or is 
   403  *  corrupt.  Currently raw and MS-ADPCM WAVE files are supported.
   404  */
   405 extern DECLSPEC SDL_AudioSpec *SDLCALL SDL_LoadWAV_RW(SDL_RWops * src,
   406                                                       int freesrc,
   407                                                       SDL_AudioSpec * spec,
   408                                                       Uint8 ** audio_buf,
   409                                                       Uint32 * audio_len);
   410 
   411 /** 
   412  *  Loads a WAV from a file.
   413  *  Compatibility convenience function.
   414  */
   415 #define SDL_LoadWAV(file, spec, audio_buf, audio_len) \
   416 	SDL_LoadWAV_RW(SDL_RWFromFile(file, "rb"),1, spec,audio_buf,audio_len)
   417 
   418 /**
   419  *  This function frees data previously allocated with SDL_LoadWAV_RW()
   420  */
   421 extern DECLSPEC void SDLCALL SDL_FreeWAV(Uint8 * audio_buf);
   422 
   423 /**
   424  *  This function takes a source format and rate and a destination format
   425  *  and rate, and initializes the \c cvt structure with information needed
   426  *  by SDL_ConvertAudio() to convert a buffer of audio data from one format
   427  *  to the other.
   428  *  
   429  *  \return -1 if the format conversion is not supported, 0 if there's
   430  *  no conversion needed, or 1 if the audio filter is set up.
   431  */
   432 extern DECLSPEC int SDLCALL SDL_BuildAudioCVT(SDL_AudioCVT * cvt,
   433                                               SDL_AudioFormat src_format,
   434                                               Uint8 src_channels,
   435                                               int src_rate,
   436                                               SDL_AudioFormat dst_format,
   437                                               Uint8 dst_channels,
   438                                               int dst_rate);
   439 
   440 /**
   441  *  Once you have initialized the \c cvt structure using SDL_BuildAudioCVT(),
   442  *  created an audio buffer \c cvt->buf, and filled it with \c cvt->len bytes of
   443  *  audio data in the source format, this function will convert it in-place
   444  *  to the desired format.
   445  *  
   446  *  The data conversion may expand the size of the audio data, so the buffer
   447  *  \c cvt->buf should be allocated after the \c cvt structure is initialized by
   448  *  SDL_BuildAudioCVT(), and should be \c cvt->len*cvt->len_mult bytes long.
   449  */
   450 extern DECLSPEC int SDLCALL SDL_ConvertAudio(SDL_AudioCVT * cvt);
   451 
   452 #define SDL_MIX_MAXVOLUME 128
   453 /**
   454  *  This takes two audio buffers of the playing audio format and mixes
   455  *  them, performing addition, volume adjustment, and overflow clipping.
   456  *  The volume ranges from 0 - 128, and should be set to ::SDL_MIX_MAXVOLUME
   457  *  for full audio volume.  Note this does not change hardware volume.
   458  *  This is provided for convenience -- you can mix your own audio data.
   459  */
   460 extern DECLSPEC void SDLCALL SDL_MixAudio(Uint8 * dst, const Uint8 * src,
   461                                           Uint32 len, int volume);
   462 
   463 /**
   464  *  This works like SDL_MixAudio(), but you specify the audio format instead of
   465  *  using the format of audio device 1. Thus it can be used when no audio
   466  *  device is open at all.
   467  */
   468 extern DECLSPEC void SDLCALL SDL_MixAudioFormat(Uint8 * dst,
   469                                                 const Uint8 * src,
   470                                                 SDL_AudioFormat format,
   471                                                 Uint32 len, int volume);
   472 
   473 /**
   474  *  \name Audio lock functions
   475  *  
   476  *  The lock manipulated by these functions protects the callback function.
   477  *  During a SDL_LockAudio()/SDL_UnlockAudio() pair, you can be guaranteed that 
   478  *  the callback function is not running.  Do not call these from the callback
   479  *  function or you will cause deadlock.
   480  */
   481 /*@{*/
   482 extern DECLSPEC void SDLCALL SDL_LockAudio(void);
   483 extern DECLSPEC void SDLCALL SDL_LockAudioDevice(SDL_AudioDeviceID dev);
   484 extern DECLSPEC void SDLCALL SDL_UnlockAudio(void);
   485 extern DECLSPEC void SDLCALL SDL_UnlockAudioDevice(SDL_AudioDeviceID dev);
   486 /*@}*//*Audio lock functions*/
   487 
   488 /**
   489  *  This function shuts down audio processing and closes the audio device.
   490  */
   491 extern DECLSPEC void SDLCALL SDL_CloseAudio(void);
   492 extern DECLSPEC void SDLCALL SDL_CloseAudioDevice(SDL_AudioDeviceID dev);
   493 
   494 /**
   495  * \return 1 if audio device is still functioning, zero if not, -1 on error.
   496  */
   497 extern DECLSPEC int SDLCALL SDL_AudioDeviceConnected(SDL_AudioDeviceID dev);
   498 
   499 
   500 /* Ends C function definitions when using C++ */
   501 #ifdef __cplusplus
   502 /* *INDENT-OFF* */
   503 }
   504 /* *INDENT-ON* */
   505 #endif
   506 #include "close_code.h"
   507 
   508 #endif /* _SDL_audio_h */
   509 
   510 /* vi: set ts=4 sw=4 expandtab: */