diff --git a/include/fluidsynth/audio.h b/include/fluidsynth/audio.h index 4eca1788..6c0e9357 100644 --- a/include/fluidsynth/audio.h +++ b/include/fluidsynth/audio.h @@ -70,12 +70,39 @@ extern "C" { * This function is responsible for rendering audio to the buffers. * The buffers passed to this function are allocated and owned by the respective * audio driver and are only valid during that specific call (do not cache them). + * The buffers have already been zeroed-out. * For further details please refer to fluid_synth_process(). * + * @parblock * @note Whereas fluid_synth_process() allows aliasing buffers, there is the guarentee that @p out * and @p fx buffers provided by fluidsynth's audio drivers never alias. This prevents downstream * applications from e.g. applying a custom effect accidentially to the same buffer multiple times. + * @endparblock * + * @parblock + * @note Also note that the Jack driver is currently the only driver that has dedicated @p fx buffers + * (but only if \setting{audio_jack_multi} is true). All other drivers do not provide @p fx buffers. + * In this case, users are encouraged to mix the effects into the provided dry buffers when calling + * fluid_synth_process(). + * @code{.cpp} +int myCallback(void *, int len, int nfx, float *fx[], int nout, float *out[]) +{ + int ret; + if(nfx == 0) + { + float *fxb[4] = {out[0], out[1], out[0], out[1]}; + ret = fluid_synth_process(synth, len, sizeof(fxb) / sizeof(fxb[0]), fxb, nout, out); + } + else + { + ret = fluid_synth_process(synth, len, nfx, fx, nout, out); + } + // ... client-code ... + return ret; +} + * @endcode + * For other possible use-cases refer to \ref fluidsynth_process.c . + * @endparblock */ typedef int (*fluid_audio_func_t)(void *data, int len, int nfx, float *fx[], diff --git a/src/synth/fluid_synth.c b/src/synth/fluid_synth.c index f0a4ab19..f5fe1225 100644 --- a/src/synth/fluid_synth.c +++ b/src/synth/fluid_synth.c @@ -3888,7 +3888,7 @@ static FLUID_INLINE void fluid_synth_mix_single_buffer(float *FLUID_RESTRICT out * @param len Count of audio frames to synthesize and store in every single buffer provided by \p out and \p fx. * Zero value is permitted, the function does nothing and return FLUID_OK. * - * @param nfx Count of arrays in \c fx. Must be a multiple of 2 (because of stereo). + * @param nfx Count of arrays in \c fx. Must be a multiple of 2 (because of stereo) * and in the range 0 <= nfx/2 <= (fluid_synth_count_effects_channels() * fluid_synth_count_effects_groups()). * Note that zero value is valid and allows to skip mixing effects in all fx output buffers. *