SDL_audio.h

00001 /*
00002   Simple DirectMedia Layer
00003   Copyright (C) 1997-2014 Sam Lantinga <slouken@libsdl.org>
00004 
00005   This software is provided 'as-is', without any express or implied
00006   warranty.  In no event will the authors be held liable for any damages
00007   arising from the use of this software.
00008 
00009   Permission is granted to anyone to use this software for any purpose,
00010   including commercial applications, and to alter it and redistribute it
00011   freely, subject to the following restrictions:
00012 
00013   1. The origin of this software must not be misrepresented; you must not
00014      claim that you wrote the original software. If you use this software
00015      in a product, an acknowledgment in the product documentation would be
00016      appreciated but is not required.
00017   2. Altered source versions must be plainly marked as such, and must not be
00018      misrepresented as being the original software.
00019   3. This notice may not be removed or altered from any source distribution.
00020 */
00021 
00022 /**
00023  *  \file SDL_audio.h
00024  *
00025  *  Access to the raw audio mixing buffer for the SDL library.
00026  */
00027 
00028 #ifndef _SDL_audio_h
00029 #define _SDL_audio_h
00030 
00031 #include "SDL_stdinc.h"
00032 #include "SDL_error.h"
00033 #include "SDL_endian.h"
00034 #include "SDL_mutex.h"
00035 #include "SDL_thread.h"
00036 #include "SDL_rwops.h"
00037 
00038 #include "begin_code.h"
00039 /* Set up for C function definitions, even when using C++ */
00040 #ifdef __cplusplus
00041 extern "C" {
00042 #endif
00043 
00044 /**
00045  *  \brief Audio format flags.
00046  *
00047  *  These are what the 16 bits in SDL_AudioFormat currently mean...
00048  *  (Unspecified bits are always zero).
00049  *
00050  *  \verbatim
00051     ++-----------------------sample is signed if set
00052     ||
00053     ||       ++-----------sample is bigendian if set
00054     ||       ||
00055     ||       ||          ++---sample is float if set
00056     ||       ||          ||
00057     ||       ||          || +---sample bit size---+
00058     ||       ||          || |                     |
00059     15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00
00060     \endverbatim
00061  *
00062  *  There are macros in SDL 2.0 and later to query these bits.
00063  */
00064 typedef Uint16 SDL_AudioFormat;
00065 
00066 /**
00067  *  \name Audio flags
00068  */
00069 /* @{ */
00070 
00071 #define SDL_AUDIO_MASK_BITSIZE       (0xFF)
00072 #define SDL_AUDIO_MASK_DATATYPE      (1<<8)
00073 #define SDL_AUDIO_MASK_ENDIAN        (1<<12)
00074 #define SDL_AUDIO_MASK_SIGNED        (1<<15)
00075 #define SDL_AUDIO_BITSIZE(x)         (x & SDL_AUDIO_MASK_BITSIZE)
00076 #define SDL_AUDIO_ISFLOAT(x)         (x & SDL_AUDIO_MASK_DATATYPE)
00077 #define SDL_AUDIO_ISBIGENDIAN(x)     (x & SDL_AUDIO_MASK_ENDIAN)
00078 #define SDL_AUDIO_ISSIGNED(x)        (x & SDL_AUDIO_MASK_SIGNED)
00079 #define SDL_AUDIO_ISINT(x)           (!SDL_AUDIO_ISFLOAT(x))
00080 #define SDL_AUDIO_ISLITTLEENDIAN(x)  (!SDL_AUDIO_ISBIGENDIAN(x))
00081 #define SDL_AUDIO_ISUNSIGNED(x)      (!SDL_AUDIO_ISSIGNED(x))
00082 
00083 /**
00084  *  \name Audio format flags
00085  *
00086  *  Defaults to LSB byte order.
00087  */
00088 /* @{ */
00089 #define AUDIO_U8        0x0008  /**< Unsigned 8-bit samples */
00090 #define AUDIO_S8        0x8008  /**< Signed 8-bit samples */
00091 #define AUDIO_U16LSB    0x0010  /**< Unsigned 16-bit samples */
00092 #define AUDIO_S16LSB    0x8010  /**< Signed 16-bit samples */
00093 #define AUDIO_U16MSB    0x1010  /**< As above, but big-endian byte order */
00094 #define AUDIO_S16MSB    0x9010  /**< As above, but big-endian byte order */
00095 #define AUDIO_U16       AUDIO_U16LSB
00096 #define AUDIO_S16       AUDIO_S16LSB
00097 /* @} */
00098 
00099 /**
00100  *  \name int32 support
00101  */
00102 /* @{ */
00103 #define AUDIO_S32LSB    0x8020  /**< 32-bit integer samples */
00104 #define AUDIO_S32MSB    0x9020  /**< As above, but big-endian byte order */
00105 #define AUDIO_S32       AUDIO_S32LSB
00106 /* @} */
00107 
00108 /**
00109  *  \name float32 support
00110  */
00111 /* @{ */
00112 #define AUDIO_F32LSB    0x8120  /**< 32-bit floating point samples */
00113 #define AUDIO_F32MSB    0x9120  /**< As above, but big-endian byte order */
00114 #define AUDIO_F32       AUDIO_F32LSB
00115 /* @} */
00116 
00117 /**
00118  *  \name Native audio byte ordering
00119  */
00120 /* @{ */
00121 #if SDL_BYTEORDER == SDL_LIL_ENDIAN
00122 #define AUDIO_U16SYS    AUDIO_U16LSB
00123 #define AUDIO_S16SYS    AUDIO_S16LSB
00124 #define AUDIO_S32SYS    AUDIO_S32LSB
00125 #define AUDIO_F32SYS    AUDIO_F32LSB
00126 #else
00127 #define AUDIO_U16SYS    AUDIO_U16MSB
00128 #define AUDIO_S16SYS    AUDIO_S16MSB
00129 #define AUDIO_S32SYS    AUDIO_S32MSB
00130 #define AUDIO_F32SYS    AUDIO_F32MSB
00131 #endif
00132 /* @} */
00133 
00134 /**
00135  *  \name Allow change flags
00136  *
00137  *  Which audio format changes are allowed when opening a device.
00138  */
00139 /* @{ */
00140 #define SDL_AUDIO_ALLOW_FREQUENCY_CHANGE    0x00000001
00141 #define SDL_AUDIO_ALLOW_FORMAT_CHANGE       0x00000002
00142 #define SDL_AUDIO_ALLOW_CHANNELS_CHANGE     0x00000004
00143 #define SDL_AUDIO_ALLOW_ANY_CHANGE          (SDL_AUDIO_ALLOW_FREQUENCY_CHANGE|SDL_AUDIO_ALLOW_FORMAT_CHANGE|SDL_AUDIO_ALLOW_CHANNELS_CHANGE)
00144 /* @} */
00145 
00146 /* @} *//* Audio flags */
00147 
00148 /**
00149  *  This function is called when the audio device needs more data.
00150  *
00151  *  \param userdata An application-specific parameter saved in
00152  *                  the SDL_AudioSpec structure
00153  *  \param stream A pointer to the audio data buffer.
00154  *  \param len    The length of that buffer in bytes.
00155  *
00156  *  Once the callback returns, the buffer will no longer be valid.
00157  *  Stereo samples are stored in a LRLRLR ordering.
00158  */
00159 typedef void (SDLCALL * SDL_AudioCallback) (void *userdata, Uint8 * stream,
00160                                             int len);
00161 
00162 /**
00163  *  The calculated values in this structure are calculated by SDL_OpenAudio().
00164  */
00165 typedef struct SDL_AudioSpec
00166 {
00167     int freq;                   /**< DSP frequency -- samples per second */
00168     SDL_AudioFormat format;     /**< Audio data format */
00169     Uint8 channels;             /**< Number of channels: 1 mono, 2 stereo */
00170     Uint8 silence;              /**< Audio buffer silence value (calculated) */
00171     Uint16 samples;             /**< Audio buffer size in samples (power of 2) */
00172     Uint16 padding;             /**< Necessary for some compile environments */
00173     Uint32 size;                /**< Audio buffer size in bytes (calculated) */
00174     SDL_AudioCallback callback;
00175     void *userdata;
00176 } SDL_AudioSpec;
00177 
00178 
00179 struct SDL_AudioCVT;
00180 typedef void (SDLCALL * SDL_AudioFilter) (struct SDL_AudioCVT * cvt,
00181                                           SDL_AudioFormat format);
00182 
00183 /**
00184  *  A structure to hold a set of audio conversion filters and buffers.
00185  */
00186 #ifdef __GNUC__
00187 /* This structure is 84 bytes on 32-bit architectures, make sure GCC doesn't
00188    pad it out to 88 bytes to guarantee ABI compatibility between compilers.
00189    vvv
00190    The next time we rev the ABI, make sure to size the ints and add padding.
00191 */
00192 #define SDL_AUDIOCVT_PACKED __attribute__((packed))
00193 #else
00194 #define SDL_AUDIOCVT_PACKED
00195 #endif
00196 /* */
00197 typedef struct SDL_AudioCVT
00198 {
00199     int needed;                 /**< Set to 1 if conversion possible */
00200     SDL_AudioFormat src_format; /**< Source audio format */
00201     SDL_AudioFormat dst_format; /**< Target audio format */
00202     double rate_incr;           /**< Rate conversion increment */
00203     Uint8 *buf;                 /**< Buffer to hold entire audio data */
00204     int len;                    /**< Length of original audio buffer */
00205     int len_cvt;                /**< Length of converted audio buffer */
00206     int len_mult;               /**< buffer must be len*len_mult big */
00207     double len_ratio;           /**< Given len, final size is len*len_ratio */
00208     SDL_AudioFilter filters[10];        /**< Filter list */
00209     int filter_index;           /**< Current audio conversion function */
00210 } SDL_AUDIOCVT_PACKED SDL_AudioCVT;
00211 
00212 
00213 /* Function prototypes */
00214 
00215 /**
00216  *  \name Driver discovery functions
00217  *
00218  *  These functions return the list of built in audio drivers, in the
00219  *  order that they are normally initialized by default.
00220  */
00221 /* @{ */
00222 extern DECLSPEC int SDLCALL SDL_GetNumAudioDrivers(void);
00223 extern DECLSPEC const char *SDLCALL SDL_GetAudioDriver(int index);
00224 /* @} */
00225 
00226 /**
00227  *  \name Initialization and cleanup
00228  *
00229  *  \internal These functions are used internally, and should not be used unless
00230  *            you have a specific need to specify the audio driver you want to
00231  *            use.  You should normally use SDL_Init() or SDL_InitSubSystem().
00232  */
00233 /* @{ */
00234 extern DECLSPEC int SDLCALL SDL_AudioInit(const char *driver_name);
00235 extern DECLSPEC void SDLCALL SDL_AudioQuit(void);
00236 /* @} */
00237 
00238 /**
00239  *  This function returns the name of the current audio driver, or NULL
00240  *  if no driver has been initialized.
00241  */
00242 extern DECLSPEC const char *SDLCALL SDL_GetCurrentAudioDriver(void);
00243 
00244 /**
00245  *  This function opens the audio device with the desired parameters, and
00246  *  returns 0 if successful, placing the actual hardware parameters in the
00247  *  structure pointed to by \c obtained.  If \c obtained is NULL, the audio
00248  *  data passed to the callback function will be guaranteed to be in the
00249  *  requested format, and will be automatically converted to the hardware
00250  *  audio format if necessary.  This function returns -1 if it failed
00251  *  to open the audio device, or couldn't set up the audio thread.
00252  *
00253  *  When filling in the desired audio spec structure,
00254  *    - \c desired->freq should be the desired audio frequency in samples-per-
00255  *      second.
00256  *    - \c desired->format should be the desired audio format.
00257  *    - \c desired->samples is the desired size of the audio buffer, in
00258  *      samples.  This number should be a power of two, and may be adjusted by
00259  *      the audio driver to a value more suitable for the hardware.  Good values
00260  *      seem to range between 512 and 8096 inclusive, depending on the
00261  *      application and CPU speed.  Smaller values yield faster response time,
00262  *      but can lead to underflow if the application is doing heavy processing
00263  *      and cannot fill the audio buffer in time.  A stereo sample consists of
00264  *      both right and left channels in LR ordering.
00265  *      Note that the number of samples is directly related to time by the
00266  *      following formula:  \code ms = (samples*1000)/freq \endcode
00267  *    - \c desired->size is the size in bytes of the audio buffer, and is
00268  *      calculated by SDL_OpenAudio().
00269  *    - \c desired->silence is the value used to set the buffer to silence,
00270  *      and is calculated by SDL_OpenAudio().
00271  *    - \c desired->callback should be set to a function that will be called
00272  *      when the audio device is ready for more data.  It is passed a pointer
00273  *      to the audio buffer, and the length in bytes of the audio buffer.
00274  *      This function usually runs in a separate thread, and so you should
00275  *      protect data structures that it accesses by calling SDL_LockAudio()
00276  *      and SDL_UnlockAudio() in your code.
00277  *    - \c desired->userdata is passed as the first parameter to your callback
00278  *      function.
00279  *
00280  *  The audio device starts out playing silence when it's opened, and should
00281  *  be enabled for playing by calling \c SDL_PauseAudio(0) when you are ready
00282  *  for your audio callback function to be called.  Since the audio driver
00283  *  may modify the requested size of the audio buffer, you should allocate
00284  *  any local mixing buffers after you open the audio device.
00285  */
00286 extern DECLSPEC int SDLCALL SDL_OpenAudio(SDL_AudioSpec * desired,
00287                                           SDL_AudioSpec * obtained);
00288 
00289 /**
00290  *  SDL Audio Device IDs.
00291  *
00292  *  A successful call to SDL_OpenAudio() is always device id 1, and legacy
00293  *  SDL audio APIs assume you want this device ID. SDL_OpenAudioDevice() calls
00294  *  always returns devices >= 2 on success. The legacy calls are good both
00295  *  for backwards compatibility and when you don't care about multiple,
00296  *  specific, or capture devices.
00297  */
00298 typedef Uint32 SDL_AudioDeviceID;
00299 
00300 /**
00301  *  Get the number of available devices exposed by the current driver.
00302  *  Only valid after a successfully initializing the audio subsystem.
00303  *  Returns -1 if an explicit list of devices can't be determined; this is
00304  *  not an error. For example, if SDL is set up to talk to a remote audio
00305  *  server, it can't list every one available on the Internet, but it will
00306  *  still allow a specific host to be specified to SDL_OpenAudioDevice().
00307  *
00308  *  In many common cases, when this function returns a value <= 0, it can still
00309  *  successfully open the default device (NULL for first argument of
00310  *  SDL_OpenAudioDevice()).
00311  */
00312 extern DECLSPEC int SDLCALL SDL_GetNumAudioDevices(int iscapture);
00313 
00314 /**
00315  *  Get the human-readable name of a specific audio device.
00316  *  Must be a value between 0 and (number of audio devices-1).
00317  *  Only valid after a successfully initializing the audio subsystem.
00318  *  The values returned by this function reflect the latest call to
00319  *  SDL_GetNumAudioDevices(); recall that function to redetect available
00320  *  hardware.
00321  *
00322  *  The string returned by this function is UTF-8 encoded, read-only, and
00323  *  managed internally. You are not to free it. If you need to keep the
00324  *  string for any length of time, you should make your own copy of it, as it
00325  *  will be invalid next time any of several other SDL functions is called.
00326  */
00327 extern DECLSPEC const char *SDLCALL SDL_GetAudioDeviceName(int index,
00328                                                            int iscapture);
00329 
00330 
00331 /**
00332  *  Open a specific audio device. Passing in a device name of NULL requests
00333  *  the most reasonable default (and is equivalent to calling SDL_OpenAudio()).
00334  *
00335  *  The device name is a UTF-8 string reported by SDL_GetAudioDeviceName(), but
00336  *  some drivers allow arbitrary and driver-specific strings, such as a
00337  *  hostname/IP address for a remote audio server, or a filename in the
00338  *  diskaudio driver.
00339  *
00340  *  \return 0 on error, a valid device ID that is >= 2 on success.
00341  *
00342  *  SDL_OpenAudio(), unlike this function, always acts on device ID 1.
00343  */
00344 extern DECLSPEC SDL_AudioDeviceID SDLCALL SDL_OpenAudioDevice(const char
00345                                                               *device,
00346                                                               int iscapture,
00347                                                               const
00348                                                               SDL_AudioSpec *
00349                                                               desired,
00350                                                               SDL_AudioSpec *
00351                                                               obtained,
00352                                                               int
00353                                                               allowed_changes);
00354 
00355 
00356 
00357 /**
00358  *  \name Audio state
00359  *
00360  *  Get the current audio state.
00361  */
00362 /* @{ */
00363 typedef enum
00364 {
00365     SDL_AUDIO_STOPPED = 0,
00366     SDL_AUDIO_PLAYING,
00367     SDL_AUDIO_PAUSED
00368 } SDL_AudioStatus;
00369 extern DECLSPEC SDL_AudioStatus SDLCALL SDL_GetAudioStatus(void);
00370 
00371 extern DECLSPEC SDL_AudioStatus SDLCALL
00372 SDL_GetAudioDeviceStatus(SDL_AudioDeviceID dev);
00373 /* @} *//* Audio State */
00374 
00375 /**
00376  *  \name Pause audio functions
00377  *
00378  *  These functions pause and unpause the audio callback processing.
00379  *  They should be called with a parameter of 0 after opening the audio
00380  *  device to start playing sound.  This is so you can safely initialize
00381  *  data for your callback function after opening the audio device.
00382  *  Silence will be written to the audio device during the pause.
00383  */
00384 /* @{ */
00385 extern DECLSPEC void SDLCALL SDL_PauseAudio(int pause_on);
00386 extern DECLSPEC void SDLCALL SDL_PauseAudioDevice(SDL_AudioDeviceID dev,
00387                                                   int pause_on);
00388 /* @} *//* Pause audio functions */
00389 
00390 /**
00391  *  This function loads a WAVE from the data source, automatically freeing
00392  *  that source if \c freesrc is non-zero.  For example, to load a WAVE file,
00393  *  you could do:
00394  *  \code
00395  *      SDL_LoadWAV_RW(SDL_RWFromFile("sample.wav", "rb"), 1, ...);
00396  *  \endcode
00397  *
00398  *  If this function succeeds, it returns the given SDL_AudioSpec,
00399  *  filled with the audio data format of the wave data, and sets
00400  *  \c *audio_buf to a malloc()'d buffer containing the audio data,
00401  *  and sets \c *audio_len to the length of that audio buffer, in bytes.
00402  *  You need to free the audio buffer with SDL_FreeWAV() when you are
00403  *  done with it.
00404  *
00405  *  This function returns NULL and sets the SDL error message if the
00406  *  wave file cannot be opened, uses an unknown data format, or is
00407  *  corrupt.  Currently raw and MS-ADPCM WAVE files are supported.
00408  */
00409 extern DECLSPEC SDL_AudioSpec *SDLCALL SDL_LoadWAV_RW(SDL_RWops * src,
00410                                                       int freesrc,
00411                                                       SDL_AudioSpec * spec,
00412                                                       Uint8 ** audio_buf,
00413                                                       Uint32 * audio_len);
00414 
00415 /**
00416  *  Loads a WAV from a file.
00417  *  Compatibility convenience function.
00418  */
00419 #define SDL_LoadWAV(file, spec, audio_buf, audio_len) \
00420     SDL_LoadWAV_RW(SDL_RWFromFile(file, "rb"),1, spec,audio_buf,audio_len)
00421 
00422 /**
00423  *  This function frees data previously allocated with SDL_LoadWAV_RW()
00424  */
00425 extern DECLSPEC void SDLCALL SDL_FreeWAV(Uint8 * audio_buf);
00426 
00427 /**
00428  *  This function takes a source format and rate and a destination format
00429  *  and rate, and initializes the \c cvt structure with information needed
00430  *  by SDL_ConvertAudio() to convert a buffer of audio data from one format
00431  *  to the other.
00432  *
00433  *  \return -1 if the format conversion is not supported, 0 if there's
00434  *  no conversion needed, or 1 if the audio filter is set up.
00435  */
00436 extern DECLSPEC int SDLCALL SDL_BuildAudioCVT(SDL_AudioCVT * cvt,
00437                                               SDL_AudioFormat src_format,
00438                                               Uint8 src_channels,
00439                                               int src_rate,
00440                                               SDL_AudioFormat dst_format,
00441                                               Uint8 dst_channels,
00442                                               int dst_rate);
00443 
00444 /**
00445  *  Once you have initialized the \c cvt structure using SDL_BuildAudioCVT(),
00446  *  created an audio buffer \c cvt->buf, and filled it with \c cvt->len bytes of
00447  *  audio data in the source format, this function will convert it in-place
00448  *  to the desired format.
00449  *
00450  *  The data conversion may expand the size of the audio data, so the buffer
00451  *  \c cvt->buf should be allocated after the \c cvt structure is initialized by
00452  *  SDL_BuildAudioCVT(), and should be \c cvt->len*cvt->len_mult bytes long.
00453  */
00454 extern DECLSPEC int SDLCALL SDL_ConvertAudio(SDL_AudioCVT * cvt);
00455 
00456 #define SDL_MIX_MAXVOLUME 128
00457 /**
00458  *  This takes two audio buffers of the playing audio format and mixes
00459  *  them, performing addition, volume adjustment, and overflow clipping.
00460  *  The volume ranges from 0 - 128, and should be set to ::SDL_MIX_MAXVOLUME
00461  *  for full audio volume.  Note this does not change hardware volume.
00462  *  This is provided for convenience -- you can mix your own audio data.
00463  */
00464 extern DECLSPEC void SDLCALL SDL_MixAudio(Uint8 * dst, const Uint8 * src,
00465                                           Uint32 len, int volume);
00466 
00467 /**
00468  *  This works like SDL_MixAudio(), but you specify the audio format instead of
00469  *  using the format of audio device 1. Thus it can be used when no audio
00470  *  device is open at all.
00471  */
00472 extern DECLSPEC void SDLCALL SDL_MixAudioFormat(Uint8 * dst,
00473                                                 const Uint8 * src,
00474                                                 SDL_AudioFormat format,
00475                                                 Uint32 len, int volume);
00476 
00477 /**
00478  *  \name Audio lock functions
00479  *
00480  *  The lock manipulated by these functions protects the callback function.
00481  *  During a SDL_LockAudio()/SDL_UnlockAudio() pair, you can be guaranteed that
00482  *  the callback function is not running.  Do not call these from the callback
00483  *  function or you will cause deadlock.
00484  */
00485 /* @{ */
00486 extern DECLSPEC void SDLCALL SDL_LockAudio(void);
00487 extern DECLSPEC void SDLCALL SDL_LockAudioDevice(SDL_AudioDeviceID dev);
00488 extern DECLSPEC void SDLCALL SDL_UnlockAudio(void);
00489 extern DECLSPEC void SDLCALL SDL_UnlockAudioDevice(SDL_AudioDeviceID dev);
00490 /* @} *//* Audio lock functions */
00491 
00492 /**
00493  *  This function shuts down audio processing and closes the audio device.
00494  */
00495 extern DECLSPEC void SDLCALL SDL_CloseAudio(void);
00496 extern DECLSPEC void SDLCALL SDL_CloseAudioDevice(SDL_AudioDeviceID dev);
00497 
00498 /* Ends C function definitions when using C++ */
00499 #ifdef __cplusplus
00500 }
00501 #endif
00502 #include "close_code.h"
00503 
00504 #endif /* _SDL_audio_h */
00505 
00506 /* vi: set ts=4 sw=4 expandtab: */