Calculate the output limiter gain using the RMS

2 files changed, 20 insertions, 1 deletions

diff --git a/OpenAL32/Include/alMain.h b/OpenAL32/Include/alMain.h
index 1b1b1909..55f52bef 100644
--- a/OpenAL32/Include/alMain.h
+++ b/OpenAL32/Include/alMain.h
@@ -391,6 +391,7 @@ extern "C" {
 
 struct Hrtf;
 struct HrtfEntry;
+struct OutputLimiter;
 
 
 #define DEFAULT_OUTPUT_RATE  (44100)
@@ -793,7 +794,7 @@ struct ALCdevice_struct
         ALsizei NumChannels;
     } RealOut;
 
-    ALfloat LimiterGain;
+    struct OutputLimiter *Limiter;
 
     /* The average speaker distance as determined by the ambdec configuration
      * (or alternatively, by the NFC-HOA reference delay). Only used for NFC.
diff --git a/OpenAL32/Include/alu.h b/OpenAL32/Include/alu.h
index 8e2fe1e9..6fdbac6f 100644
--- a/OpenAL32/Include/alu.h
+++ b/OpenAL32/Include/alu.h
@@ -297,6 +297,24 @@ typedef struct ALvoice {
 void DeinitVoice(ALvoice *voice);
 
 
+#define LIMITER_WINDOW_SIZE (1<<7) /* 128 */
+#define LIMITER_WINDOW_MASK (LIMITER_WINDOW_SIZE-1)
+struct OutputLimiter {
+    /* RMS detection window and the next write pos. */
+    alignas(16) ALfloat Window[LIMITER_WINDOW_SIZE];
+    ALsizei Pos;
+
+    /* In milliseconds. */
+    ALfloat AttackRate;
+    ALfloat ReleaseRate;
+
+    /* The gain last used for limiting. */
+    ALfloat Gain;
+};
+
+struct OutputLimiter *alloc_limiter(void);
+
+
 typedef void (*MixerFunc)(const ALfloat *data, ALsizei OutChans,
                           ALfloat (*restrict OutBuffer)[BUFFERSIZE], ALfloat *CurrentGains,
                           const ALfloat *TargetGains, ALsizei Counter, ALsizei OutPos,