leiradel / al_sfxr

SFXR sound player and generator

al_sfxr

al_sfxr is a header-only re-implementation of the original sfxr sound effect generator.

Instead of exporting wave files, al_sfxr generates audio frames during runtime directly from sfxr parameters, so it can be used to create sound effects on-the-fly for host applications.

The provided GUI application can be used to play with the parameters and export wave files, or to generate sound effects with a known seed that can be used in runtime to generate the same effect without the need of a wafe file.

Instructions

Define AL_SFXR_IMPLEMENTATION and include this file in one C or C++ file to create the implementation. If you need to declare the functions somewhere else, include this file without defining AL_SFXR_IMPLEMENTATION; the same configuration used in the implementation must be used.

To configure as_sfxr, define one or more of these macros before including this file:

• AL_SFXR_GENERATE: this macro enables al_sfxr_generate, which randomly generates a SFXR from a preset, a mutation count, and a seed.
• AL_SFXR_LOAD: define this macro to enable al_sfxr_load, used to load a SFXR file from an user-supplied reader function.
• AL_SFXR_SAVE: enables al_sfxr_save that writes the SFXR to an user-supplied writer function.
• AL_SFXR_INT16_MONO, AL_SFXR_FLOAT_MONO, AL_SFXR_INT16_STEREO, and AL_SFXR_FLOAT_STEREO: defines these macros to enable functions that will produce audio frames for a SFXR:
  • al_sfxr_produce1i: 44100 Hz, signed 16-bit mono
  • al_sfxr_produce2i: 44100 Hz, signed 16-bit stereo
  • al_sfxr_produce1f: 44100 Hz, 32-bit float mono
  • al_sfxr_produce2f: 44100 Hz, 32-bit float stereo

The API is fully documented in the al_sfxr.h file.

TL;DR

// Create a SFXR sound using the `AL_SFXR_LASER` preset, zero mutations, and 17
// as the pseudo-random number generator seed
al_sfxr_Params params;
al_sfxr_generate(&params, AL_SFXR_LASER, 0, 17);

// Save it
FILE* const fp = fopen("sfxr.bin", "wb");

if (al_sfxr_save(&params, fp_writer, (void*)fp) != 0) {
    // error
}

// Load a SFXR sound
al_sfxr_Params params;
FILE* const fp = fopen("sfxr.bin", "rb");

if (al_sfxr_load(&params, fp_reader, (void*)fp) != 0) {
    // error
}

// Play the sound
al_sfxr_Decoder decoder;
al_sfxr_start(&decoder, &params, 19); // see also al_sfxr_start_quick

while (1) {
    int16_t samples[1024 * 2]; // stereo

    // Produce 44100 Hz stereo signed 16-bit frames
    size_t const frames_written = al_sfxr_produce2i(&decoder, samples, 1024);
    size_t const samples_written = frames_written * 2;

    // Mix samples into your signed 16-bit 44100 Hz interleaved stereo output
    // sound buffer
    mix(samples, samples_written);
}

License

The MIT License (MIT)

• Copyright (c) 2007 Tomas Pettersson (original implementation)
• Copyright (c) 2020 Andre Leiradella (header only library)

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.