apps/OboeTester/app/src/main/cpp/FullDuplexEcho.cpp

/*
 * Copyright 2019 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 "common/OboeDebug.h"
#include "FullDuplexEcho.h"

oboe::Result  FullDuplexEcho::start() {
    int32_t delaySize = 3 * getOutputStream()->getSampleRate();
    mDelayFrames = delaySize - 2;
    mDelayLine = std::make_unique<InterpolatingDelayLine>(delaySize);
    return FullDuplexStream::start();
}

oboe::DataCallbackResult FullDuplexEcho::onBothStreamsReady(
        const void *inputData,
        int   numInputFrames,
        void *outputData,
        int   numOutputFrames) {
    // FIXME only handles matching stream formats.
    // TODO use array of delays
    // TODO Add delay node
    // TODO use flowgraph to handle format conversion
    int32_t framesToEcho = std::min(numInputFrames, numOutputFrames);
    float *inputFloat = (float *)inputData;
    float *outputFloat = (float *)outputData;
    int32_t inputStride = getInputStream()->getChannelCount();
    int32_t outputStride = getOutputStream()->getChannelCount();
    if (outputStride == 1) {
        while (framesToEcho-- > 0) {
            *outputFloat++ = mDelayLine->process(mDelayFrames, *inputFloat); // mono delay
            inputFloat += inputStride;
        }
    } else if (outputStride == 2) {
        while (framesToEcho-- > 0) {
            *outputFloat++ = mDelayLine->process(mDelayFrames, *inputFloat); // mono delay
            *outputFloat++ = 0.0f; // FIXME *inputFloat; // mono
            inputFloat += inputStride;
        }
    } // else TODO

    // zero out remainder of output array
    int32_t framesLeft = numOutputFrames - numInputFrames;
    if (framesLeft > 0) {
        memset(outputFloat, 0, framesLeft * getOutputStream()->getBytesPerFrame());
    }
    return oboe::DataCallbackResult::Continue;
};