From 51407dbe1cd37ef4b6f6c08a6d7c4c42158bd6b4 Mon Sep 17 00:00:00 2001
From: "dmitry.i.sokolov" <DmitryIlichSokolov@gmail.com>
Date: Thu, 8 Dec 2016 14:36:40 +0400
Subject: [PATCH] sound level

---
 .../rxandroidaudio/example/MainActivity.kt    |  4 +++-
 .../me/ilich/rxandroidaudio/AudioLevel.kt     | 19 ++++++++++++++++---
 2 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/app/src/main/kotlin/me/ilich/rxandroidaudio/example/MainActivity.kt b/app/src/main/kotlin/me/ilich/rxandroidaudio/example/MainActivity.kt
index b6a49fc..40d7c2b 100644
--- a/app/src/main/kotlin/me/ilich/rxandroidaudio/example/MainActivity.kt
+++ b/app/src/main/kotlin/me/ilich/rxandroidaudio/example/MainActivity.kt
@@ -92,13 +92,15 @@ class MainActivity : AppCompatActivity() {
 
         startLevelButton.setOnClickListener {
             val source = RecordObservable.create16bit(recordAudioOptions)
+            val lowpassFilter = LowpassFilter.crate16bit(32.0F, 1.0F, recordAudioOptions)
             subs = Observable.
                     create(source).
                     sample(500L, TimeUnit.MILLISECONDS).
+                    map { samples -> lowpassFilter.filter(samples) }.
                     map { samples ->
                         AudioLevel.maxDecibel(samples)
                     }.
-                    map { peek -> peek + 110.0 }.
+                    map { peek -> peek + 160.0 }.
                     subscribeOn(Schedulers.newThread()).
                     observeOn(AndroidSchedulers.mainThread()).
                     subscribe {
diff --git a/rxaa/src/main/kotlin/me/ilich/rxandroidaudio/AudioLevel.kt b/rxaa/src/main/kotlin/me/ilich/rxandroidaudio/AudioLevel.kt
index 8441ff3..d2cdaff 100644
--- a/rxaa/src/main/kotlin/me/ilich/rxandroidaudio/AudioLevel.kt
+++ b/rxaa/src/main/kotlin/me/ilich/rxandroidaudio/AudioLevel.kt
@@ -4,6 +4,8 @@ class AudioLevel {
 
     companion object {
 
+        private const val EPSILON = 0.001;
+
         fun rms(samples: ShortArray) = if (samples.isEmpty()) {
             0.0
         } else {
@@ -12,11 +14,22 @@ class AudioLevel {
 
         fun maxDecibel(samples: ShortArray): Double =
                 samples.
-                        map { sh -> sh.toDouble() / Short.MAX_VALUE }.
-                        map { db -> 20.0 * Math.log10(db) }.
+                        map { sh ->
+                            sh.toDouble() / Short.MAX_VALUE
+                        }.
+                        map { db ->
+                            if (db == 0.0) {
+                                EPSILON
+                            } else {
+                                Math.abs(db)
+                            }
+                        }.
+                        map { db ->
+                            20.0 * Math.log10(db)
+                        }.
                         filter(Double::isFinite).
                         max() ?:
-                        0.0
+                        Double.NEGATIVE_INFINITY
 
     }