mirror of https://github.com/ZDoom/fluidsynth.git
118 lines
4.1 KiB
C
118 lines
4.1 KiB
C
/*
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* This is a C99 program that outlines different usage examples for fluid_synth_process()
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*/
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#include <stdio.h>
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#include <string.h>
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#include <fluidsynth.h>
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int main()
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{
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// any arbitrary number of audio samples to render during on call of fluid_synth_process()
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enum { SAMPLES = 512 };
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// ...creation of synth omitted...
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// USECASE1: render all dry audio channels + reverb and chorus to one stereo channel
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{
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// planar sample buffers that received synthesized (monophonic) audio
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float left[SAMPLES], right[SAMPLES];
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// array of buffers used to setup channel mapping
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float *dry[1 * 2], *fx[1 * 2];
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// first make sure to zero out the sample buffers everytime before calling fluid_synth_process()
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memset(left, 0, sizeof(left));
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memset(right, 0, sizeof(right));
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// setup channel mapping for a single stereo channel to which to render all dry audio to
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dry[0] = left;
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dry[1] = right;
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// Setup channel mapping for a single stereo channel to which to render effects to.
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// Just using the same sample buffers as for dry audio is fine here, as it will cause the effects to be mixed with dry output.
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// Note: reverb and chorus together make up two stereo channels. Setting up only one stereo channel is sufficient
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// as the channels wraps around (i.e. chorus will be mixed with reverb channel).
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fx[0] = left;
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fx[1] = right;
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int err = fluid_synth_process(synth, SAMPLES, 2, fx, 2, dry);
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if(err == FLUID_FAILED)
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{
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puts("oops");
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}
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// USECASE2: only render dry audio and discard effects
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// same as above, but call fluid_synth_process() like:
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int err = fluid_synth_process(synth, SAMPLES, 0, NULL, 2, dry);
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if(err == FLUID_FAILED)
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{
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puts("oops");
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}
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}
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// USECASE3: render audio and discard all samples
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{
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int err = fluid_synth_process(synth, SAMPLES, 0, NULL, 0, NULL);
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if(err == FLUID_FAILED)
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{
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puts("oops");
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}
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}
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// USECASE4: multi-channel rendering, i.e. render all audio and effects channels to dedicated audio buffers
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// ofc it‘s not a good idea to allocate all the arrays on the stack
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{
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// lookup number of audio and effect (stereo-)channels of the synth
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// see "synth.audio-channels", "synth.effects-channels" and "synth.effects-groups" settings respectively
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int n_aud_chan = fluid_synth_count_audio_channels(synth);
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// by default there are two effects stereo channels (reverb and chorus) ...
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int n_fx_chan = fluid_synth_count_effects_channels(synth);
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// ... for each effects unit. Each unit takes care of the effects of one MIDI channel.
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// If there are less units than channels, it wraps around and one unit may render effects of multiple
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// MIDI channels.
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n_fx_chan *= fluid_synth_count_effects_groups();
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// for simplicity, allocate one single sample pool
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float samp_buf[SAMPLES * (n_aud_chan + n_fx_chan) * 2];
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// array of buffers used to setup channel mapping
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float *dry[n_aud_chan * 2], *fx[n_fx_chan * 2];
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// setup buffers to mix dry stereo audio to
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// buffers are alternating left and right for each n_aud_chan,
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// please review documentation of fluid_synth_process()
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for(int i = 0; i < n_aud_chan * 2; i++)
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{
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dry[i] = &samp_buf[i * SAMPLES];
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}
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// setup buffers to mix effects stereo audio to
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// similar channel layout as above, revie fluid_synth_process()
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for(int i = 0; i < n_fx_chan * 2; i++)
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{
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fx[i] = &samp_buf[n_aud_chan * 2 * SAMPLES + i * SAMPLES];
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}
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// dont forget to zero sample buffer(s) before each rendering
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memset(samp_buf, 0, sizeof(samp_buf));
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int err = fluid_synth_process(synth, SAMPLES, n_fx_chan * 2, fx, n_aud_chan * 2, dry);
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if(err == FLUID_FAILED)
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{
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puts("oops");
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}
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}
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return 0;
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}
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