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SDL_LoadWAV_RW

Load the audio data of a WAVE file into memory.

Syntax

SDL_AudioSpec* SDL_LoadWAV_RW(SDL_RWops * src,
                              int freesrc,
                              SDL_AudioSpec * spec,
                              Uint8 ** audio_buf,
                              Uint32 * audio_len);

Function Parameters

src

The data source for the WAVE data

freesrc

If non-zero, SDL will _always_ free the data source

spec

An SDL_AudioSpec that will be filled in with the wave file's format details

audio_buf

A pointer filled with the audio data, allocated by the function.

audio_len

A pointer filled with the length of the audio data buffer in bytes

Return Value

Returns This function, if successfully called, returns spec, which will be filled with the audio data format of the wave source data. audio_buf will be filled with a pointer to an allocated buffer containing the audio data, and audio_len is filled with the length of that audio buffer in bytes.

This function returns NULL if the .WAV file cannot be opened, uses an unknown data format, or is corrupt; call SDL_GetError() for more information.

When the application is done with the data returned in audio_buf, it should call SDL_FreeWAV() to dispose of it.

Remarks

Loading a WAVE file requires src, spec, audio_buf and audio_len to be valid pointers. The entire data portion of the file is then loaded into memory and decoded if necessary.

If freesrc is non-zero, the data source gets automatically closed and freed before the function returns.

Supported formats are RIFF WAVE files with the formats PCM (8, 16, 24, and 32 bits), IEEE Float (32 bits), Microsoft ADPCM and IMA ADPCM (4 bits), and A-law and mu-law (8 bits). Other formats are currently unsupported and cause an error.

If this function succeeds, the pointer returned by it is equal to spec and the pointer to the audio data allocated by the function is written to audio_buf and its length in bytes to audio_len. The SDL_AudioSpec members freq, channels, and format are set to the values of the audio data in the buffer. The samples member is set to a sane default and all others are set to zero.

It's necessary to use SDL_FreeWAV() to free the audio data returned in audio_buf when it is no longer used.

Because of the underspecification of the .WAV format, there are many problematic files in the wild that cause issues with strict decoders. To provide compatibility with these files, this decoder is lenient in regards to the truncation of the file, the fact chunk, and the size of the RIFF chunk. The hints SDL_HINT_WAVE_RIFF_CHUNK_SIZE, SDL_HINT_WAVE_TRUNCATION, and SDL_HINT_WAVE_FACT_CHUNK can be used to tune the behavior of the loading process.

Any file that is invalid (due to truncation, corruption, or wrong values in the headers), too big, or unsupported causes an error. Additionally, any critical I/O error from the data source will terminate the loading process with an error. The function returns NULL on error and in all cases (with the exception of src being NULL), an appropriate error message will be set.

It is required that the data source supports seeking.

Example:

SDL_LoadWAV_RW(SDL_RWFromFile("sample.wav", "rb"), 1, &spec, &buf, &len);

Note that the SDL_LoadWAV macro does this same thing for you, but in a less messy way:

SDL_LoadWAV("sample.wav", &spec, &buf, &len);

Code Examples

extern SDL_RWops *myRWops;
SDL_AudioSpec wav_spec;
Uint32 wav_length;
Uint8 *wav_buffer;

/* Load the WAV */
if (SDL_LoadWAV_RW(myRWops, 1, &wav_spec, &wav_buffer, &wav_length) == NULL) {
    fprintf(stderr, "Could not open test.wav: %s\n", SDL_GetError());
} else {
    /* Do stuff with the WAV data, and then... */
    SDL_FreeWAV(wav_buffer);
}
SDL_FreeWAV
SDL_LoadWAV

CategoryAPI, CategoryAudio


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