dump a MIDI to PCM with tinysoundfont

tinysoundfont-pcm.c

#include <stdint.h>
#include <stdio.h>

#define TSF_IMPLEMENTATION
#include "tsf.h"

#define TML_IMPLEMENTATION
#include "tml.h"

#define SAMPLE_RATE 22050
#define CHANNELS 1

#define PCM_BUFFER_SIZE (SAMPLE_RATE * CHANNELS * 45)
#define RENDER_BUFFER_SIZE (SAMPLE_RATE * CHANNELS * 5)

uint8_t pcm_out[PCM_BUFFER_SIZE] = {0};
volatile int sound_position = -1;

tsf *soundfont = NULL;
tml_message *midi_loader = NULL;

tml_message *midi_render_short(tsf *soundfont, tml_message *midi_message, uint8_t *buffer,
                       int samples) {
    int block_size = TSF_RENDER_EFFECTSAMPLEBLOCK;
    int bytes_written = 0;
    double msecs = 0;

    do {
        msecs += block_size * (1000.0 / SAMPLE_RATE);

        while (midi_message && msecs >= midi_message->time) {
            switch (midi_message->type) {
            case TML_PROGRAM_CHANGE:
                tsf_channel_set_presetnumber(
                    soundfont, midi_message->channel, midi_message->program,
                    (midi_message->channel == 9));
                break;
            case TML_NOTE_ON:
                tsf_channel_note_on(soundfont, midi_message->channel,
                                    midi_message->key,
                                    midi_message->velocity / 127.0f);
                break;
            case TML_NOTE_OFF:
                tsf_channel_note_off(soundfont, midi_message->channel,
                                     midi_message->key);
                break;
            case TML_PITCH_BEND:
                tsf_channel_set_pitchwheel(soundfont, midi_message->channel,
                                           midi_message->pitch_bend);
                break;
            case TML_CONTROL_CHANGE:
                tsf_channel_midi_control(soundfont, midi_message->channel,
                                         midi_message->control,
                                         midi_message->control_value);
                break;
            }

            midi_message = midi_message->next;
        }

        tsf_render_short(soundfont, (int16_t*)(buffer + bytes_written), block_size, 0);
        bytes_written += block_size * 2;
    } while (bytes_written < samples);

    return midi_message;
}