From 2c8e5cab3faa6d360e222b7a6c40a80083d021ac Mon Sep 17 00:00:00 2001
From: Eric Laurent <elaurent@google.com>
Date: Fri, 9 Jul 2010 12:28:50 -0700
Subject: First submission of audio effect library from NXP software.

This CL contains the first open sourceable version of the audio effect library from NXP software.
The effects implemented are:
- Bass boost
- Virtualizer (stereo widening)
- Equalizer
- Spectrum analyzer

Source file for the effect engines are located under libeffects/lvm/lib
The wrapper implementing the interface with the audio effect framework in under libeffects/lvm/wrapper

The code of other effect libraries has also been reorganized fo clarity:
- the effect factory is now under libeffects/factory
- the test equalizer and reverb effects are under libeffect/testlibs
- the visualizer is under libeffects/virtualizer

Change-Id: I8d91e2181f81b89f8fc0c1e1e6bf552c5809b2eb
---
 media/libeffects/testlibs/AudioPeakingFilter.cpp | 121 +++++++++++++++++++++++
 1 file changed, 121 insertions(+)
 create mode 100644 media/libeffects/testlibs/AudioPeakingFilter.cpp

(limited to 'media/libeffects/testlibs/AudioPeakingFilter.cpp')

diff --git a/media/libeffects/testlibs/AudioPeakingFilter.cpp b/media/libeffects/testlibs/AudioPeakingFilter.cpp
new file mode 100644
index 0000000..60fefe6
--- /dev/null
+++ b/media/libeffects/testlibs/AudioPeakingFilter.cpp
@@ -0,0 +1,121 @@
+/* //device/include/server/AudioFlinger/AudioPeakingFilter.cpp
+ **
+ ** Copyright 2007, The Android Open Source Project
+ **
+ ** Licensed under the Apache License, Version 2.0 (the "License");
+ ** you may not use this file except in compliance with the License.
+ ** You may obtain a copy of the License at
+ **
+ **     http://www.apache.org/licenses/LICENSE-2.0
+ **
+ ** Unless required by applicable law or agreed to in writing, software
+ ** distributed under the License is distributed on an "AS IS" BASIS,
+ ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ ** See the License for the specific language governing permissions and
+ ** limitations under the License.
+ */
+
+#include "AudioPeakingFilter.h"
+#include "AudioCommon.h"
+#include "EffectsMath.h"
+
+#include <new>
+#include <assert.h>
+
+#define LIKELY( exp )       (__builtin_expect( (exp) != 0, true  ))
+#define UNLIKELY( exp )     (__builtin_expect( (exp) != 0, false ))
+
+namespace android {
+// Format of the coefficient table:
+// kCoefTable[freq][gain][bw][coef]
+// freq - peak frequency, in octaves below Nyquist,from -9 to -1.
+// gain - gain, in millibel, starting at -9600, jumps of 1024, to 4736 millibel.
+// bw   - bandwidth, starting at 1 cent, jumps of 1024, to 3073 cents.
+// coef - 0: b0
+//        1: b1
+//        2: b2
+//        3: -a1
+//        4: -a2
+static const size_t kInDims[3] = {9, 15, 4};
+static const audio_coef_t kCoefTable[9*15*4*5] = {
+#include "AudioPeakingFilterCoef.inl"
+};
+
+AudioCoefInterpolator AudioPeakingFilter::mCoefInterp(3, kInDims, 5, (const audio_coef_t*) kCoefTable);
+
+AudioPeakingFilter::AudioPeakingFilter(int nChannels, int sampleRate)
+        : mBiquad(nChannels, sampleRate) {
+    configure(nChannels, sampleRate);
+    reset();
+}
+
+void AudioPeakingFilter::configure(int nChannels, int sampleRate) {
+    mNiquistFreq = sampleRate * 500;
+    mFrequencyFactor = ((1ull) << 42) / mNiquistFreq;
+    mBiquad.configure(nChannels, sampleRate);
+    setFrequency(mNominalFrequency);
+    commit(true);
+}
+
+void AudioPeakingFilter::reset() {
+    setGain(0);
+    setFrequency(0);
+    setBandwidth(2400);
+    commit(true);
+}
+
+void AudioPeakingFilter::setFrequency(uint32_t millihertz) {
+    mNominalFrequency = millihertz;
+    if (UNLIKELY(millihertz > mNiquistFreq / 2)) {
+        millihertz = mNiquistFreq / 2;
+    }
+    uint32_t normFreq = static_cast<uint32_t>(
+            (static_cast<uint64_t>(millihertz) * mFrequencyFactor) >> 10);
+    if (LIKELY(normFreq > (1 << 23))) {
+        mFrequency = (Effects_log2(normFreq) - ((32-9) << 15)) << (FREQ_PRECISION_BITS - 15);
+    } else {
+        mFrequency = 0;
+    }
+}
+
+void AudioPeakingFilter::setGain(int32_t millibel) {
+    mGain = millibel + 9600;
+}
+
+void AudioPeakingFilter::setBandwidth(uint32_t cents) {
+    mBandwidth = cents - 1;
+}
+
+void AudioPeakingFilter::commit(bool immediate) {
+    audio_coef_t coefs[5];
+    int intCoord[3] = {
+        mFrequency >> FREQ_PRECISION_BITS,
+        mGain >> GAIN_PRECISION_BITS,
+        mBandwidth >> BANDWIDTH_PRECISION_BITS
+    };
+    uint32_t fracCoord[3] = {
+        mFrequency << (32 - FREQ_PRECISION_BITS),
+        static_cast<uint32_t>(mGain) << (32 - GAIN_PRECISION_BITS),
+        mBandwidth << (32 - BANDWIDTH_PRECISION_BITS)
+    };
+    mCoefInterp.getCoef(intCoord, fracCoord, coefs);
+    mBiquad.setCoefs(coefs, immediate);
+}
+
+void AudioPeakingFilter::getBandRange(uint32_t & low, uint32_t & high) const {
+    // Half bandwidth, in octaves, 15-bit precision
+    int32_t halfBW = (((mBandwidth + 1) / 2) << 15) / 1200;
+
+    low = static_cast<uint32_t>((static_cast<uint64_t>(mNominalFrequency) * Effects_exp2(-halfBW + (16 << 15))) >> 16);
+    if (UNLIKELY(halfBW >= (16 << 15))) {
+        high = mNiquistFreq;
+    } else {
+        high = static_cast<uint32_t>((static_cast<uint64_t>(mNominalFrequency) * Effects_exp2(halfBW + (16 << 15))) >> 16);
+        if (UNLIKELY(high > mNiquistFreq)) {
+            high = mNiquistFreq;
+        }
+    }
+}
+
+}
+
-- 
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