src/common/SourceI24Caller.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 <algorithm>
#include <unistd.h>
#include "flowgraph/FlowGraphNode.h"
#include "SourceI24Caller.h"

#if FLOWGRAPH_ANDROID_INTERNAL
#include <audio_utils/primitives.h>
#endif

using namespace oboe;
using namespace flowgraph;

int32_t SourceI24Caller::onProcess(int32_t numFrames) {
    int32_t numBytes = mStream->getBytesPerFrame() * numFrames;
    int32_t bytesRead = mBlockReader.read((uint8_t *) mConversionBuffer.get(), numBytes);
    int32_t framesRead = bytesRead / mStream->getBytesPerFrame();

    float *floatData = output.getBuffer();
    const uint8_t *byteData = mConversionBuffer.get();
    int32_t numSamples = framesRead * output.getSamplesPerFrame();

#if FLOWGRAPH_ANDROID_INTERNAL
    memcpy_to_float_from_p24(floatData, byteData, numSamples);
#else
    static const float scale = 1. / (float)(1UL << 31);
    for (int i = 0; i < numSamples; i++) {
        // Assemble the data assuming Little Endian format.
        int32_t pad = byteData[2];
        pad <<= 8;
        pad |= byteData[1];
        pad <<= 8;
        pad |= byteData[0];
        pad <<= 8; // Shift to 32 bit data so the sign is correct.
        byteData += kBytesPerI24Packed;
        *floatData++ = pad * scale; // scale to range -1.0 to 1.0
    }
#endif

    return framesRead;
}