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      1 /*
      2  * Copyright 2015 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #define LOG_TAG "RampLinear"
     18 //#define LOG_NDEBUG 0
     19 #include <utils/Log.h>
     20 
     21 #include <algorithm>
     22 #include <unistd.h>
     23 #include "AudioProcessorBase.h"
     24 #include "RampLinear.h"
     25 
     26 using namespace flowgraph;
     27 
     28 RampLinear::RampLinear(int32_t channelCount)
     29         : input(*this, channelCount)
     30         , output(*this, channelCount) {
     31     mTarget.store(1.0f);
     32 }
     33 
     34 void RampLinear::setLengthInFrames(int32_t frames) {
     35     mLengthInFrames = frames;
     36 }
     37 
     38 void RampLinear::setTarget(float target) {
     39     mTarget.store(target);
     40 }
     41 
     42 float RampLinear::interpolateCurrent() {
     43     return mLevelTo - (mRemaining * mScaler);
     44 }
     45 
     46 int32_t RampLinear::onProcess(int64_t framePosition, int32_t numFrames) {
     47     int32_t framesToProcess = input.pullData(framePosition, numFrames);
     48     const float *inputBuffer = input.getBlock();
     49     float *outputBuffer = output.getBlock();
     50     int32_t channelCount = output.getSamplesPerFrame();
     51 
     52     float target = getTarget();
     53     if (target != mLevelTo) {
     54         // Start new ramp. Continue from previous level.
     55         mLevelFrom = interpolateCurrent();
     56         mLevelTo = target;
     57         mRemaining = mLengthInFrames;
     58         ALOGV("%s() mLevelFrom = %f, mLevelTo = %f, mRemaining = %d, mScaler = %f",
     59               __func__, mLevelFrom, mLevelTo, mRemaining, mScaler);
     60         mScaler = (mLevelTo - mLevelFrom) / mLengthInFrames; // for interpolation
     61     }
     62 
     63     int32_t framesLeft = framesToProcess;
     64 
     65     if (mRemaining > 0) { // Ramping? This doesn't happen very often.
     66         int32_t framesToRamp = std::min(framesLeft, mRemaining);
     67         framesLeft -= framesToRamp;
     68         while (framesToRamp > 0) {
     69             float currentLevel = interpolateCurrent();
     70             for (int ch = 0; ch < channelCount; ch++) {
     71                 *outputBuffer++ = *inputBuffer++ * currentLevel;
     72             }
     73             mRemaining--;
     74             framesToRamp--;
     75         }
     76     }
     77 
     78     // Process any frames after the ramp.
     79     int32_t samplesLeft = framesLeft * channelCount;
     80     for (int i = 0; i < samplesLeft; i++) {
     81         *outputBuffer++ = *inputBuffer++ * mLevelTo;
     82     }
     83 
     84     return framesToProcess;
     85 }
     86