65 lines
1.5 KiB
C
65 lines
1.5 KiB
C
#include <audio.h>
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#include <stdio.h>
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void audioCallback(void *userdata, uint8_t *stream, int len) {
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AudioContext *aud;
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SDL_assert(len == 834 * 4);
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aud = userdata;
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if (!aud->filled) {
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/* too little data, play silence */
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SDL_memset4(stream, 0, 834);
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return;
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}
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SDL_memcpy4(stream, aud->buffers[aud->current], 834);
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++aud->current;
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aud->current %= 2;
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aud->filled -= 1;
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}
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int audioInit(AudioContext *aud) {
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SDL_AudioSpec spec;
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spec.freq = 41700;
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spec.format = AUDIO_S16;
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spec.channels = 2;
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spec.samples = 834;
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spec.callback = &audioCallback;
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spec.userdata = aud;
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aud->id = SDL_OpenAudioDevice(NULL, 0, &spec, NULL, 0);
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aud->paused = true;
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if (!aud->id) {
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fprintf(stderr, "could not open audio device: %s\n", SDL_GetError());
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return -1;
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}
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aud->current = 0;
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aud->filled = 0;
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return 0;
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}
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int audioUpdate(AudioContext *aud, void *data, uint32_t bytes) {
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int filled;
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if (!aud->id) return -1;
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SDL_assert(bytes == 834 * 4);
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SDL_LockAudioDevice(aud->id);
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if (aud->filled < 2) {
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int next = (aud->current + aud->filled) % 2;
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SDL_memcpy4(aud->buffers[next], data, bytes / 4);
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aud->filled += 1;
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}
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filled = aud->filled;
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SDL_UnlockAudioDevice(aud->id);
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if (aud->paused) {
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SDL_PauseAudioDevice(aud->id, false);
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aud->paused = false;
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}
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while (filled > 1) {
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SDL_Delay(0);
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filled = aud->filled;
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}
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return 0;
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} |