AudioPlatform_Portaudio.cpp

/* Copyright 2016, Ableton AG, Berlin. All rights reserved.
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 *  If you would like to incorporate Link into a proprietary software application,
 *  please contact <link-devs@ableton.com>.
 */

#include "AudioPlatform_Portaudio.hpp"
#include <chrono>
#include <iostream>

namespace ableton
{
namespace linkaudio
{

AudioPlatform::AudioPlatform(Link& link)
  : mEngine(link)
  , mSampleTime(0.)
{
  mEngine.setSampleRate(44100.);
  mEngine.setBufferSize(512);
  initialize();
  start();
}

AudioPlatform::~AudioPlatform()
{
  stop();
  uninitialize();
}

int AudioPlatform::audioCallback(const void* /*inputBuffer*/,
  void* outputBuffer,
  unsigned long inNumFrames,
  const PaStreamCallbackTimeInfo* /*timeInfo*/,
  PaStreamCallbackFlags /*statusFlags*/,
  void* userData)
{
  using namespace std::chrono;
  float* buffer = static_cast<float*>(outputBuffer);
  AudioPlatform& platform = *static_cast<AudioPlatform*>(userData);
  AudioEngine& engine = platform.mEngine;

  const auto hostTime =
    platform.mHostTimeFilter.sampleTimeToHostTime(platform.mSampleTime);

  platform.mSampleTime += static_cast<double>(inNumFrames);

  const auto bufferBeginAtOutput = hostTime + engine.mOutputLatency.load();

  engine.audioCallback(bufferBeginAtOutput, inNumFrames);

  for (unsigned long i = 0; i < inNumFrames; ++i)
  {
    buffer[i * 2] = static_cast<float>(engine.mBuffer[i]);
    buffer[i * 2 + 1] = static_cast<float>(engine.mBuffer[i]);
  }

  return paContinue;
}

void AudioPlatform::initialize()
{
  PaError result = Pa_Initialize();
  if (result)
  {
    std::cerr << "Could not initialize Audio Engine. " << result << std::endl;
    std::terminate();
  }

  PaStreamParameters outputParameters;
  outputParameters.device = Pa_GetDefaultOutputDevice();
  if (outputParameters.device == paNoDevice)
  {
    std::cerr << "Could not get Audio Device. " << std::endl;
    std::terminate();
  }

  outputParameters.channelCount = 2;
  outputParameters.sampleFormat = paFloat32;
  outputParameters.suggestedLatency =
    Pa_GetDeviceInfo(outputParameters.device)->defaultLowOutputLatency;
  outputParameters.hostApiSpecificStreamInfo = nullptr;
  mEngine.mOutputLatency.store(
    std::chrono::microseconds(llround(outputParameters.suggestedLatency * 1.0e6)));
  result = Pa_OpenStream(&pStream, nullptr, &outputParameters, mEngine.mSampleRate,
    mEngine.mBuffer.size(), paClipOff, &audioCallback, this);

  if (result)
  {
    std::cerr << "Could not open stream. " << result << std::endl;
    std::terminate();
  }

  if (!pStream)
  {
    std::cerr << "No valid audio stream." << std::endl;
    std::terminate();
  }
}

void AudioPlatform::uninitialize()
{
  PaError result = Pa_CloseStream(pStream);
  if (result)
  {
    std::cerr << "Could not close Audio Stream. " << result << std::endl;
  }
  Pa_Terminate();

  if (!pStream)
  {
    std::cerr << "No valid audio stream." << std::endl;
    std::terminate();
  }
}

void AudioPlatform::start()
{
  PaError result = Pa_StartStream(pStream);
  if (result)
  {
    std::cerr << "Could not start Audio Stream. " << result << std::endl;
  }
}

void AudioPlatform::stop()
{
  if (pStream == nullptr)
  {
    return;
  }

  PaError result = Pa_StopStream(pStream);
  if (result)
  {
    std::cerr << "Could not stop Audio Stream. " << result << std::endl;
    std::terminate();
  }
}

} // namespace linkaudio
} // namespace ableton