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-rw-r--r--src/AudioCompress/compress.c185
-rw-r--r--src/AudioCompress/compress.h40
-rw-r--r--src/AudioCompress/config.h19
3 files changed, 244 insertions, 0 deletions
diff --git a/src/AudioCompress/compress.c b/src/AudioCompress/compress.c
new file mode 100644
index 000000000..36cdfd8dd
--- /dev/null
+++ b/src/AudioCompress/compress.c
@@ -0,0 +1,185 @@
+/* compress.c
+ * Compressor logic
+ *
+ * (c)2007 busybee (http://beesbuzz.biz/
+ * Licensed under the terms of the LGPL. See the file COPYING for details.
+ */
+
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "config.h"
+#include "compress.h"
+
+struct Compressor {
+ //! The compressor's preferences
+ struct CompressorConfig prefs;
+
+ //! History of the peak values
+ int *peaks;
+
+ //! History of the gain values
+ int *gain;
+
+ //! History of clip amounts
+ int *clipped;
+
+ unsigned int pos;
+ unsigned int bufsz;
+};
+
+struct Compressor *Compressor_new(unsigned int history)
+{
+ struct Compressor *obj = malloc(sizeof(struct Compressor));
+
+ obj->prefs.target = TARGET;
+ obj->prefs.maxgain = GAINMAX;
+ obj->prefs.smooth = GAINSMOOTH;
+
+ obj->peaks = obj->gain = obj->clipped = NULL;
+ obj->bufsz = 0;
+ obj->pos = 0;
+
+ Compressor_setHistory(obj, history);
+
+ return obj;
+}
+
+void Compressor_delete(struct Compressor *obj)
+{
+ if (obj->peaks)
+ free(obj->peaks);
+ if (obj->gain)
+ free(obj->gain);
+ if (obj->clipped)
+ free(obj->clipped);
+ free(obj);
+}
+
+static int *resizeArray(int *data, int newsz, int oldsz)
+{
+ data = realloc(data, newsz*sizeof(int));
+ if (newsz > oldsz)
+ memset(data + oldsz, 0, sizeof(int)*(newsz - oldsz));
+ return data;
+}
+
+void Compressor_setHistory(struct Compressor *obj, unsigned int history)
+{
+ if (!history)
+ history = BUCKETS;
+
+ obj->peaks = resizeArray(obj->peaks, history, obj->bufsz);
+ obj->gain = resizeArray(obj->gain, history, obj->bufsz);
+ obj->clipped = resizeArray(obj->clipped, history, obj->bufsz);
+ obj->bufsz = history;
+}
+
+struct CompressorConfig *Compressor_getConfig(struct Compressor *obj)
+{
+ return &obj->prefs;
+}
+
+void Compressor_Process_int16(struct Compressor *obj, int16_t *audio,
+ unsigned int count)
+{
+ struct CompressorConfig *prefs = Compressor_getConfig(obj);
+ int16_t *ap;
+ unsigned int i;
+ int *peaks = obj->peaks;
+ int curGain = obj->gain[obj->pos];
+ int newGain;
+ int peakVal = 1;
+ int peakPos = 0;
+ int slot = (obj->pos + 1) % obj->bufsz;
+ int *clipped = obj->clipped + slot;
+ unsigned int ramp = count;
+ int delta;
+
+ ap = audio;
+ for (i = 0; i < count; i++)
+ {
+ int val = *ap++;
+ if (val < 0)
+ val = -val;
+ if (val > peakVal)
+ {
+ peakVal = val;
+ peakPos = i;
+ }
+ }
+ peaks[slot] = peakVal;
+
+
+ for (i = 0; i < obj->bufsz; i++)
+ {
+ if (peaks[i] > peakVal)
+ {
+ peakVal = peaks[i];
+ peakPos = 0;
+ }
+ }
+
+ //! Determine target gain
+ newGain = (1 << 10)*prefs->target/peakVal;
+
+ //! Adjust the gain with inertia from the previous gain value
+ newGain = (curGain*((1 << prefs->smooth) - 1) + newGain)
+ >> prefs->smooth;
+
+ //! Make sure it's no more than the maximum gain value
+ if (newGain > (prefs->maxgain << 10))
+ newGain = prefs->maxgain << 10;
+
+ //! Make sure it's no less than 1:1
+ if (newGain < (1 << 10))
+ newGain = 1 << 10;
+
+ //! Make sure the adjusted gain won't cause clipping
+ if ((peakVal*newGain >> 10) > 32767)
+ {
+ newGain = (32767 << 10)/peakVal;
+ //! Truncate the ramp time
+ ramp = peakPos;
+ }
+
+ //! Record the new gain
+ obj->gain[slot] = newGain;
+
+ if (!ramp)
+ ramp = 1;
+ if (!curGain)
+ curGain = 1 << 10;
+ delta = (newGain - curGain) / (int)ramp;
+
+ ap = audio;
+ *clipped = 0;
+ for (i = 0; i < count; i++)
+ {
+ int sample;
+
+ //! Amplify the sample
+ sample = *ap*curGain >> 10;
+ if (sample < -32768)
+ {
+ *clipped += -32768 - sample;
+ sample = -32768;
+ } else if (sample > 32767)
+ {
+ *clipped += sample - 32767;
+ sample = 32767;
+ }
+ *ap++ = sample;
+
+ //! Adjust the gain
+ if (i < ramp)
+ curGain += delta;
+ else
+ curGain = newGain;
+ }
+
+ obj->pos = slot;
+}
+
diff --git a/src/AudioCompress/compress.h b/src/AudioCompress/compress.h
new file mode 100644
index 000000000..073d4af9a
--- /dev/null
+++ b/src/AudioCompress/compress.h
@@ -0,0 +1,40 @@
+/*! compress.h
+ * interface to audio compression
+ *
+ * (c)2007 busybee (http://beesbuzz.biz/)
+ * Licensed under the terms of the LGPL. See the file COPYING for details.
+ */
+
+#ifndef COMPRESS_H
+#define COMPRESS_H
+
+#include <stdint.h>
+
+//! Configuration values for the compressor object
+struct CompressorConfig {
+ int target;
+ int maxgain;
+ int smooth;
+};
+
+struct Compressor;
+
+//! Create a new compressor (use history value of 0 for default)
+struct Compressor *Compressor_new(unsigned int history);
+
+//! Delete a compressor
+void Compressor_delete(struct Compressor *);
+
+//! Set the history length
+void Compressor_setHistory(struct Compressor *, unsigned int history);
+
+//! Get the configuration for a compressor
+struct CompressorConfig *Compressor_getConfig(struct Compressor *);
+
+//! Process 16-bit signed data
+void Compressor_Process_int16(struct Compressor *, int16_t *data, unsigned int count);
+
+//! TODO: Compressor_Process_int32, Compressor_Process_float, others as needed
+
+//! TODO: functions for getting at the peak/gain/clip history buffers (for monitoring)
+#endif
diff --git a/src/AudioCompress/config.h b/src/AudioCompress/config.h
new file mode 100644
index 000000000..25615ee68
--- /dev/null
+++ b/src/AudioCompress/config.h
@@ -0,0 +1,19 @@
+/* config.h
+** Default values for the configuration, and also a few random debug things
+*/
+
+#ifndef AC_CONFIG_H
+#define AC_CONFIG_H
+
+/*** Version information ***/
+#define ACVERSION "2.0"
+
+/*** Default configuration stuff ***/
+#define TARGET 16384 /*!< Target level (on a scale of 0-32767) */
+
+#define GAINMAX 32 /*!< The maximum amount to amplify by */
+#define GAINSMOOTH 8 /*!< How much inertia ramping has*/
+#define BUCKETS 400 /*!< How long of a history to use by default */
+
+#endif
+
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