include/SDL_audio.h
author Sam Lantinga <slouken@libsdl.org>
Thu, 10 Dec 2009 08:28:26 +0000
changeset 3537 e897a4a9f578
parent 3407 d3baf5ac4e37
child 3554 cf815007e443
permissions -rw-r--r--
Switch to mixed case for consistency with other enumerations
     1 /*
     2     SDL - Simple DirectMedia Layer
     3     Copyright (C) 1997-2009 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  *  The calculated values in this structure are calculated by SDL_OpenAudio().
   157  */
   158 typedef struct SDL_AudioSpec
   159 {
   160     int freq;                   /**< DSP frequency -- samples per second */
   161     SDL_AudioFormat format;     /**< Audio data format */
   162     Uint8 channels;             /**< Number of channels: 1 mono, 2 stereo */
   163     Uint8 silence;              /**< Audio buffer silence value (calculated) */
   164     Uint16 samples;             /**< Audio buffer size in samples (power of 2) */
   165     Uint16 padding;             /**< Necessary for some compile environments */
   166     Uint32 size;                /**< Audio buffer size in bytes (calculated) */
   167     /**
   168      *  This function is called when the audio device needs more data.
   169      *
   170      *  \param stream A pointer to the audio data buffer.
   171      *  \param len    The length of that buffer in bytes.
   172      *
   173      *  Once the callback returns, the buffer will no longer be valid.
   174      *  Stereo samples are stored in a LRLRLR ordering.
   175      */
   176     void (SDLCALL * callback) (void *userdata, Uint8 * stream, int len);
   177     void *userdata;
   178 } SDL_AudioSpec;
   179 
   180 
   181 struct SDL_AudioCVT;
   182 typedef void (SDLCALL * SDL_AudioFilter) (struct SDL_AudioCVT * cvt,
   183                                           SDL_AudioFormat format);
   184 
   185 /**
   186  *  A structure to hold a set of audio conversion filters and buffers.
   187  */
   188 typedef struct SDL_AudioCVT
   189 {
   190     int needed;                 /**< Set to 1 if conversion possible */
   191     SDL_AudioFormat src_format; /**< Source audio format */
   192     SDL_AudioFormat dst_format; /**< Target audio format */
   193     double rate_incr;           /**< Rate conversion increment */
   194     Uint8 *buf;                 /**< Buffer to hold entire audio data */
   195     int len;                    /**< Length of original audio buffer */
   196     int len_cvt;                /**< Length of converted audio buffer */
   197     int len_mult;               /**< buffer must be len*len_mult big */
   198     double len_ratio;           /**< Given len, final size is len*len_ratio */
   199     SDL_AudioFilter filters[10];        /**< Filter list */
   200     int filter_index;           /**< Current audio conversion function */
   201 } SDL_AudioCVT;
   202 
   203 
   204 /* Function prototypes */
   205 
   206 /**
   207  *  \name Driver discovery functions
   208  *  
   209  *  These functions return the list of built in audio drivers, in the
   210  *  order that they are normally initialized by default.
   211  */
   212 /*@{*/
   213 extern DECLSPEC int SDLCALL SDL_GetNumAudioDrivers(void);
   214 extern DECLSPEC const char *SDLCALL SDL_GetAudioDriver(int index);
   215 /*@}*/
   216 
   217 /**
   218  *  \name Initialization and cleanup
   219  *  
   220  *  \internal These functions are used internally, and should not be used unless
   221  *            you have a specific need to specify the audio driver you want to 
   222  *            use.  You should normally use SDL_Init() or SDL_InitSubSystem().
   223  */
   224 /*@{*/
   225 extern DECLSPEC int SDLCALL SDL_AudioInit(const char *driver_name);
   226 extern DECLSPEC void SDLCALL SDL_AudioQuit(void);
   227 /*@}*/
   228 
   229 /**
   230  *  This function returns the name of the current audio driver, or NULL
   231  *  if no driver has been initialized.
   232  */
   233 extern DECLSPEC const char *SDLCALL SDL_GetCurrentAudioDriver(void);
   234 
   235 /**
   236  *  This function opens the audio device with the desired parameters, and
   237  *  returns 0 if successful, placing the actual hardware parameters in the
   238  *  structure pointed to by \c obtained.  If \c obtained is NULL, the audio
   239  *  data passed to the callback function will be guaranteed to be in the
   240  *  requested format, and will be automatically converted to the hardware
   241  *  audio format if necessary.  This function returns -1 if it failed 
   242  *  to open the audio device, or couldn't set up the audio thread.
   243  *  
   244  *  When filling in the desired audio spec structure,
   245  *    - \c desired->freq should be the desired audio frequency in samples-per-
   246  *      second.
   247  *    - \c desired->format should be the desired audio format.
   248  *    - \c desired->samples is the desired size of the audio buffer, in 
   249  *      samples.  This number should be a power of two, and may be adjusted by 
   250  *      the audio driver to a value more suitable for the hardware.  Good values
   251  *      seem to range between 512 and 8096 inclusive, depending on the 
   252  *      application and CPU speed.  Smaller values yield faster response time, 
   253  *      but can lead to underflow if the application is doing heavy processing 
   254  *      and cannot fill the audio buffer in time.  A stereo sample consists of 
   255  *      both right and left channels in LR ordering.
   256  *      Note that the number of samples is directly related to time by the
   257  *      following formula:  \code ms = (samples*1000)/freq \endcode
   258  *    - \c desired->size is the size in bytes of the audio buffer, and is
   259  *      calculated by SDL_OpenAudio().
   260  *    - \c desired->silence is the value used to set the buffer to silence,
   261  *      and is calculated by SDL_OpenAudio().
   262  *    - \c desired->callback should be set to a function that will be called
   263  *      when the audio device is ready for more data.  It is passed a pointer
   264  *      to the audio buffer, and the length in bytes of the audio buffer.
   265  *      This function usually runs in a separate thread, and so you should
   266  *      protect data structures that it accesses by calling SDL_LockAudio()
   267  *      and SDL_UnlockAudio() in your code.
   268  *    - \c desired->userdata is passed as the first parameter to your callback
   269  *      function.
   270  *  
   271  *  The audio device starts out playing silence when it's opened, and should
   272  *  be enabled for playing by calling \c SDL_PauseAudio(0) when you are ready
   273  *  for your audio callback function to be called.  Since the audio driver
   274  *  may modify the requested size of the audio buffer, you should allocate
   275  *  any local mixing buffers after you open the audio device.
   276  */
   277 extern DECLSPEC int SDLCALL SDL_OpenAudio(SDL_AudioSpec * desired,
   278                                           SDL_AudioSpec * obtained);
   279 
   280 /**
   281  *  SDL Audio Device IDs.
   282  *  
   283  *  A successful call to SDL_OpenAudio() is always device id 1, and legacy
   284  *  SDL audio APIs assume you want this device ID. SDL_OpenAudioDevice() calls
   285  *  always returns devices >= 2 on success. The legacy calls are good both
   286  *  for backwards compatibility and when you don't care about multiple,
   287  *  specific, or capture devices.
   288  */
   289 typedef Uint32 SDL_AudioDeviceID;
   290 
   291 /**
   292  *  Get the number of available devices exposed by the current driver.
   293  *  Only valid after a successfully initializing the audio subsystem.
   294  *  Returns -1 if an explicit list of devices can't be determined; this is
   295  *  not an error. For example, if SDL is set up to talk to a remote audio
   296  *  server, it can't list every one available on the Internet, but it will
   297  *  still allow a specific host to be specified to SDL_OpenAudioDevice().
   298  *  
   299  *  In many common cases, when this function returns a value <= 0, it can still
   300  *  successfully open the default device (NULL for first argument of
   301  *  SDL_OpenAudioDevice()).
   302  */
   303 extern DECLSPEC int SDLCALL SDL_GetNumAudioDevices(int iscapture);
   304 
   305 /**
   306  *  Get the human-readable name of a specific audio device.
   307  *  Must be a value between 0 and (number of audio devices-1).
   308  *  Only valid after a successfully initializing the audio subsystem.
   309  *  The values returned by this function reflect the latest call to
   310  *  SDL_GetNumAudioDevices(); recall that function to redetect available
   311  *  hardware.
   312  *  
   313  *  The string returned by this function is UTF-8 encoded, read-only, and
   314  *  managed internally. You are not to free it. If you need to keep the
   315  *  string for any length of time, you should make your own copy of it, as it
   316  *  will be invalid next time any of several other SDL functions is called.
   317  */
   318 extern DECLSPEC const char *SDLCALL SDL_GetAudioDeviceName(int index,
   319                                                            int iscapture);
   320 
   321 
   322 /**
   323  *  Open a specific audio device. Passing in a device name of NULL requests
   324  *  the most reasonable default (and is equivalent to calling SDL_OpenAudio()).
   325  *  
   326  *  The device name is a UTF-8 string reported by SDL_GetAudioDeviceName(), but
   327  *  some drivers allow arbitrary and driver-specific strings, such as a
   328  *  hostname/IP address for a remote audio server, or a filename in the
   329  *  diskaudio driver.
   330  *  
   331  *  \return 0 on error, a valid device ID that is >= 2 on success.
   332  *  
   333  *  SDL_OpenAudio(), unlike this function, always acts on device ID 1.
   334  */
   335 extern DECLSPEC SDL_AudioDeviceID SDLCALL SDL_OpenAudioDevice(const char
   336                                                               *device,
   337                                                               int iscapture,
   338                                                               const
   339                                                               SDL_AudioSpec *
   340                                                               desired,
   341                                                               SDL_AudioSpec *
   342                                                               obtained,
   343                                                               int
   344                                                               allowed_changes);
   345 
   346 
   347 
   348 /**
   349  *  \name Audio state
   350  *  
   351  *  Get the current audio state.
   352  */
   353 /*@{*/
   354 typedef enum
   355 {
   356     SDL_AUDIO_STOPPED = 0,
   357     SDL_AUDIO_PLAYING,
   358     SDL_AUDIO_PAUSED
   359 } SDL_AudioStatus;
   360 extern DECLSPEC SDL_AudioStatus SDLCALL SDL_GetAudioStatus(void);
   361 
   362 extern DECLSPEC SDL_AudioStatus SDLCALL
   363 SDL_GetAudioDeviceStatus(SDL_AudioDeviceID dev);
   364 /*@}*//*Audio State*/
   365 
   366 /**
   367  *  \name Pause audio functions
   368  *  
   369  *  These functions pause and unpause the audio callback processing.
   370  *  They should be called with a parameter of 0 after opening the audio
   371  *  device to start playing sound.  This is so you can safely initialize
   372  *  data for your callback function after opening the audio device.
   373  *  Silence will be written to the audio device during the pause.
   374  */
   375 /*@{*/
   376 extern DECLSPEC void SDLCALL SDL_PauseAudio(int pause_on);
   377 extern DECLSPEC void SDLCALL SDL_PauseAudioDevice(SDL_AudioDeviceID dev,
   378                                                   int pause_on);
   379 /*@}*//*Pause audio functions*/
   380 
   381 /**
   382  *  This function loads a WAVE from the data source, automatically freeing
   383  *  that source if \c freesrc is non-zero.  For example, to load a WAVE file,
   384  *  you could do:
   385  *  \code
   386  *  	SDL_LoadWAV_RW(SDL_RWFromFile("sample.wav", "rb"), 1, ...);
   387  *  \endcode
   388  *
   389  *  If this function succeeds, it returns the given SDL_AudioSpec,
   390  *  filled with the audio data format of the wave data, and sets
   391  *  \c *audio_buf to a malloc()'d buffer containing the audio data,
   392  *  and sets \c *audio_len to the length of that audio buffer, in bytes.
   393  *  You need to free the audio buffer with SDL_FreeWAV() when you are 
   394  *  done with it.
   395  *
   396  *  This function returns NULL and sets the SDL error message if the 
   397  *  wave file cannot be opened, uses an unknown data format, or is 
   398  *  corrupt.  Currently raw and MS-ADPCM WAVE files are supported.
   399  */
   400 extern DECLSPEC SDL_AudioSpec *SDLCALL SDL_LoadWAV_RW(SDL_RWops * src,
   401                                                       int freesrc,
   402                                                       SDL_AudioSpec * spec,
   403                                                       Uint8 ** audio_buf,
   404                                                       Uint32 * audio_len);
   405 
   406 /** 
   407  *  Loads a WAV from a file.
   408  *  Compatibility convenience function.
   409  */
   410 #define SDL_LoadWAV(file, spec, audio_buf, audio_len) \
   411 	SDL_LoadWAV_RW(SDL_RWFromFile(file, "rb"),1, spec,audio_buf,audio_len)
   412 
   413 /**
   414  *  This function frees data previously allocated with SDL_LoadWAV_RW()
   415  */
   416 extern DECLSPEC void SDLCALL SDL_FreeWAV(Uint8 * audio_buf);
   417 
   418 /**
   419  *  This function takes a source format and rate and a destination format
   420  *  and rate, and initializes the \c cvt structure with information needed
   421  *  by SDL_ConvertAudio() to convert a buffer of audio data from one format
   422  *  to the other.
   423  *  
   424  *  \return -1 if the format conversion is not supported, 0 if there's
   425  *  no conversion needed, or 1 if the audio filter is set up.
   426  */
   427 extern DECLSPEC int SDLCALL SDL_BuildAudioCVT(SDL_AudioCVT * cvt,
   428                                               SDL_AudioFormat src_format,
   429                                               Uint8 src_channels,
   430                                               int src_rate,
   431                                               SDL_AudioFormat dst_format,
   432                                               Uint8 dst_channels,
   433                                               int dst_rate);
   434 
   435 /**
   436  *  Once you have initialized the \c cvt structure using SDL_BuildAudioCVT(),
   437  *  created an audio buffer \c cvt->buf, and filled it with \c cvt->len bytes of
   438  *  audio data in the source format, this function will convert it in-place
   439  *  to the desired format.
   440  *  
   441  *  The data conversion may expand the size of the audio data, so the buffer
   442  *  \c cvt->buf should be allocated after the \c cvt structure is initialized by
   443  *  SDL_BuildAudioCVT(), and should be \c cvt->len*cvt->len_mult bytes long.
   444  */
   445 extern DECLSPEC int SDLCALL SDL_ConvertAudio(SDL_AudioCVT * cvt);
   446 
   447 #define SDL_MIX_MAXVOLUME 128
   448 /**
   449  *  This takes two audio buffers of the playing audio format and mixes
   450  *  them, performing addition, volume adjustment, and overflow clipping.
   451  *  The volume ranges from 0 - 128, and should be set to ::SDL_MIX_MAXVOLUME
   452  *  for full audio volume.  Note this does not change hardware volume.
   453  *  This is provided for convenience -- you can mix your own audio data.
   454  */
   455 extern DECLSPEC void SDLCALL SDL_MixAudio(Uint8 * dst, const Uint8 * src,
   456                                           Uint32 len, int volume);
   457 
   458 /**
   459  *  This works like SDL_MixAudio(), but you specify the audio format instead of
   460  *  using the format of audio device 1. Thus it can be used when no audio
   461  *  device is open at all.
   462  */
   463 extern DECLSPEC void SDLCALL SDL_MixAudioFormat(Uint8 * dst,
   464                                                 const Uint8 * src,
   465                                                 SDL_AudioFormat format,
   466                                                 Uint32 len, int volume);
   467 
   468 /**
   469  *  \name Audio lock functions
   470  *  
   471  *  The lock manipulated by these functions protects the callback function.
   472  *  During a SDL_LockAudio()/SDL_UnlockAudio() pair, you can be guaranteed that 
   473  *  the callback function is not running.  Do not call these from the callback
   474  *  function or you will cause deadlock.
   475  */
   476 /*@{*/
   477 extern DECLSPEC void SDLCALL SDL_LockAudio(void);
   478 extern DECLSPEC void SDLCALL SDL_LockAudioDevice(SDL_AudioDeviceID dev);
   479 extern DECLSPEC void SDLCALL SDL_UnlockAudio(void);
   480 extern DECLSPEC void SDLCALL SDL_UnlockAudioDevice(SDL_AudioDeviceID dev);
   481 /*@}*//*Audio lock functions*/
   482 
   483 /**
   484  *  This function shuts down audio processing and closes the audio device.
   485  */
   486 extern DECLSPEC void SDLCALL SDL_CloseAudio(void);
   487 extern DECLSPEC void SDLCALL SDL_CloseAudioDevice(SDL_AudioDeviceID dev);
   488 
   489 /**
   490  * \return 1 if audio device is still functioning, zero if not, -1 on error.
   491  */
   492 extern DECLSPEC int SDLCALL SDL_AudioDeviceConnected(SDL_AudioDeviceID dev);
   493 
   494 
   495 /* Ends C function definitions when using C++ */
   496 #ifdef __cplusplus
   497 /* *INDENT-OFF* */
   498 }
   499 /* *INDENT-ON* */
   500 #endif
   501 #include "close_code.h"
   502 
   503 #endif /* _SDL_audio_h */
   504 
   505 /* vi: set ts=4 sw=4 expandtab: */