include/SDL_audio.h
author Sam Lantinga <slouken@libsdl.org>
Sun, 09 Mar 2014 11:06:11 -0700
changeset 8582 c3e9a2b93517
parent 7678 286c42d7c5ed
child 8149 681eb46b8ac4
permissions -rw-r--r--
Fixed line endings on WinRT source code
     1 /*
     2   Simple DirectMedia Layer
     3   Copyright (C) 1997-2013 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 extern "C" {
    42 #endif
    43 
    44 /**
    45  *  \brief Audio format flags.
    46  *
    47  *  These are what the 16 bits in SDL_AudioFormat currently mean...
    48  *  (Unspecified bits are always zero).
    49  *
    50  *  \verbatim
    51     ++-----------------------sample is signed if set
    52     ||
    53     ||       ++-----------sample is bigendian if set
    54     ||       ||
    55     ||       ||          ++---sample is float if set
    56     ||       ||          ||
    57     ||       ||          || +---sample bit size---+
    58     ||       ||          || |                     |
    59     15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00
    60     \endverbatim
    61  *
    62  *  There are macros in SDL 2.0 and later to query these bits.
    63  */
    64 typedef Uint16 SDL_AudioFormat;
    65 
    66 /**
    67  *  \name Audio flags
    68  */
    69 /* @{ */
    70 
    71 #define SDL_AUDIO_MASK_BITSIZE       (0xFF)
    72 #define SDL_AUDIO_MASK_DATATYPE      (1<<8)
    73 #define SDL_AUDIO_MASK_ENDIAN        (1<<12)
    74 #define SDL_AUDIO_MASK_SIGNED        (1<<15)
    75 #define SDL_AUDIO_BITSIZE(x)         (x & SDL_AUDIO_MASK_BITSIZE)
    76 #define SDL_AUDIO_ISFLOAT(x)         (x & SDL_AUDIO_MASK_DATATYPE)
    77 #define SDL_AUDIO_ISBIGENDIAN(x)     (x & SDL_AUDIO_MASK_ENDIAN)
    78 #define SDL_AUDIO_ISSIGNED(x)        (x & SDL_AUDIO_MASK_SIGNED)
    79 #define SDL_AUDIO_ISINT(x)           (!SDL_AUDIO_ISFLOAT(x))
    80 #define SDL_AUDIO_ISLITTLEENDIAN(x)  (!SDL_AUDIO_ISBIGENDIAN(x))
    81 #define SDL_AUDIO_ISUNSIGNED(x)      (!SDL_AUDIO_ISSIGNED(x))
    82 
    83 /**
    84  *  \name Audio format flags
    85  *
    86  *  Defaults to LSB byte order.
    87  */
    88 /* @{ */
    89 #define AUDIO_U8        0x0008  /**< Unsigned 8-bit samples */
    90 #define AUDIO_S8        0x8008  /**< Signed 8-bit samples */
    91 #define AUDIO_U16LSB    0x0010  /**< Unsigned 16-bit samples */
    92 #define AUDIO_S16LSB    0x8010  /**< Signed 16-bit samples */
    93 #define AUDIO_U16MSB    0x1010  /**< As above, but big-endian byte order */
    94 #define AUDIO_S16MSB    0x9010  /**< As above, but big-endian byte order */
    95 #define AUDIO_U16       AUDIO_U16LSB
    96 #define AUDIO_S16       AUDIO_S16LSB
    97 /* @} */
    98 
    99 /**
   100  *  \name int32 support
   101  */
   102 /* @{ */
   103 #define AUDIO_S32LSB    0x8020  /**< 32-bit integer samples */
   104 #define AUDIO_S32MSB    0x9020  /**< As above, but big-endian byte order */
   105 #define AUDIO_S32       AUDIO_S32LSB
   106 /* @} */
   107 
   108 /**
   109  *  \name float32 support
   110  */
   111 /* @{ */
   112 #define AUDIO_F32LSB    0x8120  /**< 32-bit floating point samples */
   113 #define AUDIO_F32MSB    0x9120  /**< As above, but big-endian byte order */
   114 #define AUDIO_F32       AUDIO_F32LSB
   115 /* @} */
   116 
   117 /**
   118  *  \name Native audio byte ordering
   119  */
   120 /* @{ */
   121 #if SDL_BYTEORDER == SDL_LIL_ENDIAN
   122 #define AUDIO_U16SYS    AUDIO_U16LSB
   123 #define AUDIO_S16SYS    AUDIO_S16LSB
   124 #define AUDIO_S32SYS    AUDIO_S32LSB
   125 #define AUDIO_F32SYS    AUDIO_F32LSB
   126 #else
   127 #define AUDIO_U16SYS    AUDIO_U16MSB
   128 #define AUDIO_S16SYS    AUDIO_S16MSB
   129 #define AUDIO_S32SYS    AUDIO_S32MSB
   130 #define AUDIO_F32SYS    AUDIO_F32MSB
   131 #endif
   132 /* @} */
   133 
   134 /**
   135  *  \name Allow change flags
   136  *
   137  *  Which audio format changes are allowed when opening a device.
   138  */
   139 /* @{ */
   140 #define SDL_AUDIO_ALLOW_FREQUENCY_CHANGE    0x00000001
   141 #define SDL_AUDIO_ALLOW_FORMAT_CHANGE       0x00000002
   142 #define SDL_AUDIO_ALLOW_CHANNELS_CHANGE     0x00000004
   143 #define SDL_AUDIO_ALLOW_ANY_CHANGE          (SDL_AUDIO_ALLOW_FREQUENCY_CHANGE|SDL_AUDIO_ALLOW_FORMAT_CHANGE|SDL_AUDIO_ALLOW_CHANNELS_CHANGE)
   144 /* @} */
   145 
   146 /* @} *//* Audio flags */
   147 
   148 /**
   149  *  This function is called when the audio device needs more data.
   150  *
   151  *  \param userdata An application-specific parameter saved in
   152  *                  the SDL_AudioSpec structure
   153  *  \param stream A pointer to the audio data buffer.
   154  *  \param len    The length of that buffer in bytes.
   155  *
   156  *  Once the callback returns, the buffer will no longer be valid.
   157  *  Stereo samples are stored in a LRLRLR ordering.
   158  */
   159 typedef void (SDLCALL * SDL_AudioCallback) (void *userdata, Uint8 * stream,
   160                                             int len);
   161 
   162 /**
   163  *  The calculated values in this structure are calculated by SDL_OpenAudio().
   164  */
   165 typedef struct SDL_AudioSpec
   166 {
   167     int freq;                   /**< DSP frequency -- samples per second */
   168     SDL_AudioFormat format;     /**< Audio data format */
   169     Uint8 channels;             /**< Number of channels: 1 mono, 2 stereo */
   170     Uint8 silence;              /**< Audio buffer silence value (calculated) */
   171     Uint16 samples;             /**< Audio buffer size in samples (power of 2) */
   172     Uint16 padding;             /**< Necessary for some compile environments */
   173     Uint32 size;                /**< Audio buffer size in bytes (calculated) */
   174     SDL_AudioCallback callback;
   175     void *userdata;
   176 } SDL_AudioSpec;
   177 
   178 
   179 struct SDL_AudioCVT;
   180 typedef void (SDLCALL * SDL_AudioFilter) (struct SDL_AudioCVT * cvt,
   181                                           SDL_AudioFormat format);
   182 
   183 /**
   184  *  A structure to hold a set of audio conversion filters and buffers.
   185  */
   186 #ifdef __GNUC__
   187 /* This structure is 84 bytes on 32-bit architectures, make sure GCC doesn't
   188    pad it out to 88 bytes to guarantee ABI compatibility between compilers.
   189    vvv
   190    The next time we rev the ABI, make sure to size the ints and add padding.
   191 */
   192 #define SDL_AUDIOCVT_PACKED __attribute__((packed))
   193 #else
   194 #define SDL_AUDIOCVT_PACKED
   195 #endif
   196 /* */
   197 typedef struct SDL_AudioCVT
   198 {
   199     int needed;                 /**< Set to 1 if conversion possible */
   200     SDL_AudioFormat src_format; /**< Source audio format */
   201     SDL_AudioFormat dst_format; /**< Target audio format */
   202     double rate_incr;           /**< Rate conversion increment */
   203     Uint8 *buf;                 /**< Buffer to hold entire audio data */
   204     int len;                    /**< Length of original audio buffer */
   205     int len_cvt;                /**< Length of converted audio buffer */
   206     int len_mult;               /**< buffer must be len*len_mult big */
   207     double len_ratio;           /**< Given len, final size is len*len_ratio */
   208     SDL_AudioFilter filters[10];        /**< Filter list */
   209     int filter_index;           /**< Current audio conversion function */
   210 } SDL_AUDIOCVT_PACKED SDL_AudioCVT;
   211 
   212 
   213 /* Function prototypes */
   214 
   215 /**
   216  *  \name Driver discovery functions
   217  *
   218  *  These functions return the list of built in audio drivers, in the
   219  *  order that they are normally initialized by default.
   220  */
   221 /* @{ */
   222 extern DECLSPEC int SDLCALL SDL_GetNumAudioDrivers(void);
   223 extern DECLSPEC const char *SDLCALL SDL_GetAudioDriver(int index);
   224 /* @} */
   225 
   226 /**
   227  *  \name Initialization and cleanup
   228  *
   229  *  \internal These functions are used internally, and should not be used unless
   230  *            you have a specific need to specify the audio driver you want to
   231  *            use.  You should normally use SDL_Init() or SDL_InitSubSystem().
   232  */
   233 /* @{ */
   234 extern DECLSPEC int SDLCALL SDL_AudioInit(const char *driver_name);
   235 extern DECLSPEC void SDLCALL SDL_AudioQuit(void);
   236 /* @} */
   237 
   238 /**
   239  *  This function returns the name of the current audio driver, or NULL
   240  *  if no driver has been initialized.
   241  */
   242 extern DECLSPEC const char *SDLCALL SDL_GetCurrentAudioDriver(void);
   243 
   244 /**
   245  *  This function opens the audio device with the desired parameters, and
   246  *  returns 0 if successful, placing the actual hardware parameters in the
   247  *  structure pointed to by \c obtained.  If \c obtained is NULL, the audio
   248  *  data passed to the callback function will be guaranteed to be in the
   249  *  requested format, and will be automatically converted to the hardware
   250  *  audio format if necessary.  This function returns -1 if it failed
   251  *  to open the audio device, or couldn't set up the audio thread.
   252  *
   253  *  When filling in the desired audio spec structure,
   254  *    - \c desired->freq should be the desired audio frequency in samples-per-
   255  *      second.
   256  *    - \c desired->format should be the desired audio format.
   257  *    - \c desired->samples is the desired size of the audio buffer, in
   258  *      samples.  This number should be a power of two, and may be adjusted by
   259  *      the audio driver to a value more suitable for the hardware.  Good values
   260  *      seem to range between 512 and 8096 inclusive, depending on the
   261  *      application and CPU speed.  Smaller values yield faster response time,
   262  *      but can lead to underflow if the application is doing heavy processing
   263  *      and cannot fill the audio buffer in time.  A stereo sample consists of
   264  *      both right and left channels in LR ordering.
   265  *      Note that the number of samples is directly related to time by the
   266  *      following formula:  \code ms = (samples*1000)/freq \endcode
   267  *    - \c desired->size is the size in bytes of the audio buffer, and is
   268  *      calculated by SDL_OpenAudio().
   269  *    - \c desired->silence is the value used to set the buffer to silence,
   270  *      and is calculated by SDL_OpenAudio().
   271  *    - \c desired->callback should be set to a function that will be called
   272  *      when the audio device is ready for more data.  It is passed a pointer
   273  *      to the audio buffer, and the length in bytes of the audio buffer.
   274  *      This function usually runs in a separate thread, and so you should
   275  *      protect data structures that it accesses by calling SDL_LockAudio()
   276  *      and SDL_UnlockAudio() in your code.
   277  *    - \c desired->userdata is passed as the first parameter to your callback
   278  *      function.
   279  *
   280  *  The audio device starts out playing silence when it's opened, and should
   281  *  be enabled for playing by calling \c SDL_PauseAudio(0) when you are ready
   282  *  for your audio callback function to be called.  Since the audio driver
   283  *  may modify the requested size of the audio buffer, you should allocate
   284  *  any local mixing buffers after you open the audio device.
   285  */
   286 extern DECLSPEC int SDLCALL SDL_OpenAudio(SDL_AudioSpec * desired,
   287                                           SDL_AudioSpec * obtained);
   288 
   289 /**
   290  *  SDL Audio Device IDs.
   291  *
   292  *  A successful call to SDL_OpenAudio() is always device id 1, and legacy
   293  *  SDL audio APIs assume you want this device ID. SDL_OpenAudioDevice() calls
   294  *  always returns devices >= 2 on success. The legacy calls are good both
   295  *  for backwards compatibility and when you don't care about multiple,
   296  *  specific, or capture devices.
   297  */
   298 typedef Uint32 SDL_AudioDeviceID;
   299 
   300 /**
   301  *  Get the number of available devices exposed by the current driver.
   302  *  Only valid after a successfully initializing the audio subsystem.
   303  *  Returns -1 if an explicit list of devices can't be determined; this is
   304  *  not an error. For example, if SDL is set up to talk to a remote audio
   305  *  server, it can't list every one available on the Internet, but it will
   306  *  still allow a specific host to be specified to SDL_OpenAudioDevice().
   307  *
   308  *  In many common cases, when this function returns a value <= 0, it can still
   309  *  successfully open the default device (NULL for first argument of
   310  *  SDL_OpenAudioDevice()).
   311  */
   312 extern DECLSPEC int SDLCALL SDL_GetNumAudioDevices(int iscapture);
   313 
   314 /**
   315  *  Get the human-readable name of a specific audio device.
   316  *  Must be a value between 0 and (number of audio devices-1).
   317  *  Only valid after a successfully initializing the audio subsystem.
   318  *  The values returned by this function reflect the latest call to
   319  *  SDL_GetNumAudioDevices(); recall that function to redetect available
   320  *  hardware.
   321  *
   322  *  The string returned by this function is UTF-8 encoded, read-only, and
   323  *  managed internally. You are not to free it. If you need to keep the
   324  *  string for any length of time, you should make your own copy of it, as it
   325  *  will be invalid next time any of several other SDL functions is called.
   326  */
   327 extern DECLSPEC const char *SDLCALL SDL_GetAudioDeviceName(int index,
   328                                                            int iscapture);
   329 
   330 
   331 /**
   332  *  Open a specific audio device. Passing in a device name of NULL requests
   333  *  the most reasonable default (and is equivalent to calling SDL_OpenAudio()).
   334  *
   335  *  The device name is a UTF-8 string reported by SDL_GetAudioDeviceName(), but
   336  *  some drivers allow arbitrary and driver-specific strings, such as a
   337  *  hostname/IP address for a remote audio server, or a filename in the
   338  *  diskaudio driver.
   339  *
   340  *  \return 0 on error, a valid device ID that is >= 2 on success.
   341  *
   342  *  SDL_OpenAudio(), unlike this function, always acts on device ID 1.
   343  */
   344 extern DECLSPEC SDL_AudioDeviceID SDLCALL SDL_OpenAudioDevice(const char
   345                                                               *device,
   346                                                               int iscapture,
   347                                                               const
   348                                                               SDL_AudioSpec *
   349                                                               desired,
   350                                                               SDL_AudioSpec *
   351                                                               obtained,
   352                                                               int
   353                                                               allowed_changes);
   354 
   355 
   356 
   357 /**
   358  *  \name Audio state
   359  *
   360  *  Get the current audio state.
   361  */
   362 /* @{ */
   363 typedef enum
   364 {
   365     SDL_AUDIO_STOPPED = 0,
   366     SDL_AUDIO_PLAYING,
   367     SDL_AUDIO_PAUSED
   368 } SDL_AudioStatus;
   369 extern DECLSPEC SDL_AudioStatus SDLCALL SDL_GetAudioStatus(void);
   370 
   371 extern DECLSPEC SDL_AudioStatus SDLCALL
   372 SDL_GetAudioDeviceStatus(SDL_AudioDeviceID dev);
   373 /* @} *//* Audio State */
   374 
   375 /**
   376  *  \name Pause audio functions
   377  *
   378  *  These functions pause and unpause the audio callback processing.
   379  *  They should be called with a parameter of 0 after opening the audio
   380  *  device to start playing sound.  This is so you can safely initialize
   381  *  data for your callback function after opening the audio device.
   382  *  Silence will be written to the audio device during the pause.
   383  */
   384 /* @{ */
   385 extern DECLSPEC void SDLCALL SDL_PauseAudio(int pause_on);
   386 extern DECLSPEC void SDLCALL SDL_PauseAudioDevice(SDL_AudioDeviceID dev,
   387                                                   int pause_on);
   388 /* @} *//* Pause audio functions */
   389 
   390 /**
   391  *  This function loads a WAVE from the data source, automatically freeing
   392  *  that source if \c freesrc is non-zero.  For example, to load a WAVE file,
   393  *  you could do:
   394  *  \code
   395  *      SDL_LoadWAV_RW(SDL_RWFromFile("sample.wav", "rb"), 1, ...);
   396  *  \endcode
   397  *
   398  *  If this function succeeds, it returns the given SDL_AudioSpec,
   399  *  filled with the audio data format of the wave data, and sets
   400  *  \c *audio_buf to a malloc()'d buffer containing the audio data,
   401  *  and sets \c *audio_len to the length of that audio buffer, in bytes.
   402  *  You need to free the audio buffer with SDL_FreeWAV() when you are
   403  *  done with it.
   404  *
   405  *  This function returns NULL and sets the SDL error message if the
   406  *  wave file cannot be opened, uses an unknown data format, or is
   407  *  corrupt.  Currently raw and MS-ADPCM WAVE files are supported.
   408  */
   409 extern DECLSPEC SDL_AudioSpec *SDLCALL SDL_LoadWAV_RW(SDL_RWops * src,
   410                                                       int freesrc,
   411                                                       SDL_AudioSpec * spec,
   412                                                       Uint8 ** audio_buf,
   413                                                       Uint32 * audio_len);
   414 
   415 /**
   416  *  Loads a WAV from a file.
   417  *  Compatibility convenience function.
   418  */
   419 #define SDL_LoadWAV(file, spec, audio_buf, audio_len) \
   420     SDL_LoadWAV_RW(SDL_RWFromFile(file, "rb"),1, spec,audio_buf,audio_len)
   421 
   422 /**
   423  *  This function frees data previously allocated with SDL_LoadWAV_RW()
   424  */
   425 extern DECLSPEC void SDLCALL SDL_FreeWAV(Uint8 * audio_buf);
   426 
   427 /**
   428  *  This function takes a source format and rate and a destination format
   429  *  and rate, and initializes the \c cvt structure with information needed
   430  *  by SDL_ConvertAudio() to convert a buffer of audio data from one format
   431  *  to the other.
   432  *
   433  *  \return -1 if the format conversion is not supported, 0 if there's
   434  *  no conversion needed, or 1 if the audio filter is set up.
   435  */
   436 extern DECLSPEC int SDLCALL SDL_BuildAudioCVT(SDL_AudioCVT * cvt,
   437                                               SDL_AudioFormat src_format,
   438                                               Uint8 src_channels,
   439                                               int src_rate,
   440                                               SDL_AudioFormat dst_format,
   441                                               Uint8 dst_channels,
   442                                               int dst_rate);
   443 
   444 /**
   445  *  Once you have initialized the \c cvt structure using SDL_BuildAudioCVT(),
   446  *  created an audio buffer \c cvt->buf, and filled it with \c cvt->len bytes of
   447  *  audio data in the source format, this function will convert it in-place
   448  *  to the desired format.
   449  *
   450  *  The data conversion may expand the size of the audio data, so the buffer
   451  *  \c cvt->buf should be allocated after the \c cvt structure is initialized by
   452  *  SDL_BuildAudioCVT(), and should be \c cvt->len*cvt->len_mult bytes long.
   453  */
   454 extern DECLSPEC int SDLCALL SDL_ConvertAudio(SDL_AudioCVT * cvt);
   455 
   456 #define SDL_MIX_MAXVOLUME 128
   457 /**
   458  *  This takes two audio buffers of the playing audio format and mixes
   459  *  them, performing addition, volume adjustment, and overflow clipping.
   460  *  The volume ranges from 0 - 128, and should be set to ::SDL_MIX_MAXVOLUME
   461  *  for full audio volume.  Note this does not change hardware volume.
   462  *  This is provided for convenience -- you can mix your own audio data.
   463  */
   464 extern DECLSPEC void SDLCALL SDL_MixAudio(Uint8 * dst, const Uint8 * src,
   465                                           Uint32 len, int volume);
   466 
   467 /**
   468  *  This works like SDL_MixAudio(), but you specify the audio format instead of
   469  *  using the format of audio device 1. Thus it can be used when no audio
   470  *  device is open at all.
   471  */
   472 extern DECLSPEC void SDLCALL SDL_MixAudioFormat(Uint8 * dst,
   473                                                 const Uint8 * src,
   474                                                 SDL_AudioFormat format,
   475                                                 Uint32 len, int volume);
   476 
   477 /**
   478  *  \name Audio lock functions
   479  *
   480  *  The lock manipulated by these functions protects the callback function.
   481  *  During a SDL_LockAudio()/SDL_UnlockAudio() pair, you can be guaranteed that
   482  *  the callback function is not running.  Do not call these from the callback
   483  *  function or you will cause deadlock.
   484  */
   485 /* @{ */
   486 extern DECLSPEC void SDLCALL SDL_LockAudio(void);
   487 extern DECLSPEC void SDLCALL SDL_LockAudioDevice(SDL_AudioDeviceID dev);
   488 extern DECLSPEC void SDLCALL SDL_UnlockAudio(void);
   489 extern DECLSPEC void SDLCALL SDL_UnlockAudioDevice(SDL_AudioDeviceID dev);
   490 /* @} *//* Audio lock functions */
   491 
   492 /**
   493  *  This function shuts down audio processing and closes the audio device.
   494  */
   495 extern DECLSPEC void SDLCALL SDL_CloseAudio(void);
   496 extern DECLSPEC void SDLCALL SDL_CloseAudioDevice(SDL_AudioDeviceID dev);
   497 
   498 /* Ends C function definitions when using C++ */
   499 #ifdef __cplusplus
   500 }
   501 #endif
   502 #include "close_code.h"
   503 
   504 #endif /* _SDL_audio_h */
   505 
   506 /* vi: set ts=4 sw=4 expandtab: */