summaryrefslogtreecommitdiffstats
path: root/third_party/libwebrtc/modules/audio_processing/agc/utility.cc
diff options
context:
space:
mode:
Diffstat (limited to 'third_party/libwebrtc/modules/audio_processing/agc/utility.cc')
-rw-r--r--third_party/libwebrtc/modules/audio_processing/agc/utility.cc39
1 files changed, 39 insertions, 0 deletions
diff --git a/third_party/libwebrtc/modules/audio_processing/agc/utility.cc b/third_party/libwebrtc/modules/audio_processing/agc/utility.cc
new file mode 100644
index 0000000000..2a87e5ce74
--- /dev/null
+++ b/third_party/libwebrtc/modules/audio_processing/agc/utility.cc
@@ -0,0 +1,39 @@
+/*
+ * Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
+ *
+ * Use of this source code is governed by a BSD-style license
+ * that can be found in the LICENSE file in the root of the source
+ * tree. An additional intellectual property rights grant can be found
+ * in the file PATENTS. All contributing project authors may
+ * be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "modules/audio_processing/agc/utility.h"
+
+#include <math.h>
+
+namespace webrtc {
+
+static const double kLog10 = 2.30258509299;
+static const double kLinear2DbScale = 20.0 / kLog10;
+static const double kLinear2LoudnessScale = 13.4 / kLog10;
+
+double Loudness2Db(double loudness) {
+ return loudness * kLinear2DbScale / kLinear2LoudnessScale;
+}
+
+double Linear2Loudness(double rms) {
+ if (rms == 0)
+ return -15;
+ return kLinear2LoudnessScale * log(rms);
+}
+
+double Db2Loudness(double db) {
+ return db * kLinear2LoudnessScale / kLinear2DbScale;
+}
+
+double Dbfs2Loudness(double dbfs) {
+ return Db2Loudness(90 + dbfs);
+}
+
+} // namespace webrtc