JUCE/modules/juce_audio_devices/sources/juce_AudioSourcePlayer.cpp

/*
  ==============================================================================

   This file is part of the JUCE library.
   Copyright (c) 2017 - ROLI Ltd.

   JUCE is an open source library subject to commercial or open-source
   licensing.

   The code included in this file is provided under the terms of the ISC license
   http://www.isc.org/downloads/software-support-policy/isc-license. Permission
   To use, copy, modify, and/or distribute this software for any purpose with or
   without fee is hereby granted provided that the above copyright notice and
   this permission notice appear in all copies.

   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
   DISCLAIMED.

  ==============================================================================
*/

namespace juce
{

AudioSourcePlayer::AudioSourcePlayer()
{
}

AudioSourcePlayer::~AudioSourcePlayer()
{
    setSource (nullptr);
}

void AudioSourcePlayer::setSource (AudioSource* newSource)
{
    if (source != newSource)
    {
        auto* oldSource = source;

        if (newSource != nullptr && bufferSize > 0 && sampleRate > 0)
            newSource->prepareToPlay (bufferSize, sampleRate);

        {
            const ScopedLock sl (readLock);
            source = newSource;
        }

        if (oldSource != nullptr)
            oldSource->releaseResources();
    }
}

void AudioSourcePlayer::setGain (const float newGain) noexcept
{
    gain = newGain;
}

void AudioSourcePlayer::audioDeviceIOCallback (const float** inputChannelData,
                                               int totalNumInputChannels,
                                               float** outputChannelData,
                                               int totalNumOutputChannels,
                                               int numSamples)
{
    // these should have been prepared by audioDeviceAboutToStart()...
    jassert (sampleRate > 0 && bufferSize > 0);

    const ScopedLock sl (readLock);

    if (source != nullptr)
    {
        int numActiveChans = 0, numInputs = 0, numOutputs = 0;

        // messy stuff needed to compact the channels down into an array
        // of non-zero pointers..
        for (int i = 0; i < totalNumInputChannels; ++i)
        {
            if (inputChannelData[i] != nullptr)
            {
                inputChans [numInputs++] = inputChannelData[i];
                if (numInputs >= numElementsInArray (inputChans))
                    break;
            }
        }

        for (int i = 0; i < totalNumOutputChannels; ++i)
        {
            if (outputChannelData[i] != nullptr)
            {
                outputChans [numOutputs++] = outputChannelData[i];
                if (numOutputs >= numElementsInArray (outputChans))
                    break;
            }
        }

        if (numInputs > numOutputs)
        {
            // if there aren't enough output channels for the number of
            // inputs, we need to create some temporary extra ones (can't
            // use the input data in case it gets written to)
            tempBuffer.setSize (numInputs - numOutputs, numSamples,
                                false, false, true);

            for (int i = 0; i < numOutputs; ++i)
            {
                channels[numActiveChans] = outputChans[i];
                memcpy (channels[numActiveChans], inputChans[i], (size_t) numSamples * sizeof (float));
                ++numActiveChans;
            }

            for (int i = numOutputs; i < numInputs; ++i)
            {
                channels[numActiveChans] = tempBuffer.getWritePointer (i - numOutputs);
                memcpy (channels[numActiveChans], inputChans[i], (size_t) numSamples * sizeof (float));
                ++numActiveChans;
            }
        }
        else
        {
            for (int i = 0; i < numInputs; ++i)
            {
                channels[numActiveChans] = outputChans[i];
                memcpy (channels[numActiveChans], inputChans[i], (size_t) numSamples * sizeof (float));
                ++numActiveChans;
            }

            for (int i = numInputs; i < numOutputs; ++i)
            {
                channels[numActiveChans] = outputChans[i];
                zeromem (channels[numActiveChans], (size_t) numSamples * sizeof (float));
                ++numActiveChans;
            }
        }

        AudioBuffer<float> buffer (channels, numActiveChans, numSamples);

        AudioSourceChannelInfo info (&buffer, 0, numSamples);
        source->getNextAudioBlock (info);

        for (int i = info.buffer->getNumChannels(); --i >= 0;)
            buffer.applyGainRamp (i, info.startSample, info.numSamples, lastGain, gain);

        lastGain = gain;
    }
    else
    {
        for (int i = 0; i < totalNumOutputChannels; ++i)
            if (outputChannelData[i] != nullptr)
                zeromem (outputChannelData[i], (size_t) numSamples * sizeof (float));
    }
}

void AudioSourcePlayer::audioDeviceAboutToStart (AudioIODevice* device)
{
    prepareToPlay (device->getCurrentSampleRate(),
                   device->getCurrentBufferSizeSamples());
}

void AudioSourcePlayer::prepareToPlay (double newSampleRate, int newBufferSize)
{
    sampleRate = newSampleRate;
    bufferSize = newBufferSize;
    zeromem (channels, sizeof (channels));

    if (source != nullptr)
        source->prepareToPlay (bufferSize, sampleRate);
}

void AudioSourcePlayer::audioDeviceStopped()
{
    if (source != nullptr)
        source->releaseResources();

    sampleRate = 0.0;
    bufferSize = 0;

    tempBuffer.setSize (2, 8);
}

} // namespace juce