Adds dynamic audio rate control option

When DRC is on, game syncs to frame rate instead of audio buffer
capacity. Audio is resampled to generate more samples when buffer is
low and less when buffer is high, to keep buffer 40%-60% full. Buffer
size doubled to keep same avg. audio latency value.

Audio can distort when buffer is out of range, not often during
gameplay. Better resampler could improve but would be slower. When
buffer is always out of range (heavy frameskip), it is better to leave
off, DRC doesn't help anyway then.

Idea from RetroArch audio_driver.c and
https://near.sh/articles/audio/dynamic-rate-control

1 files changed, 1 insertions, 0 deletions

diff --git a/options.h b/options.h
index 268a619..c76e251 100644
--- a/options.h
+++ b/options.h
@@ -8,6 +8,7 @@ extern int show_cpu;
 extern int show_hud;
 extern int limit_frames;
 extern int enable_audio;
+extern int enable_drc;
 extern unsigned audio_buffer_size;
 extern enum scale_size scale_size;
 extern enum scale_filter scale_filter;