services/media/audio/platform/linux/alsa_output.h

// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef SERVICES_MEDIA_AUDIO_PLATFORM_LINUX_ALSA_OUTPUT_H_
#define SERVICES_MEDIA_AUDIO_PLATFORM_LINUX_ALSA_OUTPUT_H_

#include <alsa/asoundlib.h>
#include <memory>

#include "mojo/services/media/common/cpp/linear_transform.h"
#include "mojo/services/media/common/interfaces/media_types.mojom.h"
#include "services/media/audio/audio_output.h"
#include "services/media/audio/platform/generic/standard_output_base.h"

namespace mojo {
namespace media {
namespace audio {

class AlsaOutput : public StandardOutputBase {
 public:
  static AudioOutputPtr New(AudioOutputManager* manager);
  ~AlsaOutput() override;

  MediaResult Configure(LpcmMediaTypeDetailsPtr config);

 protected:
  explicit AlsaOutput(AudioOutputManager* manager);

  // AudioOutput implementation
  MediaResult Init() override;
  void Cleanup() override;

  // StandardOutputBase implementation
  bool StartMixJob(MixJob* job, const LocalTime& process_start) override;
  bool FinishMixJob(const MixJob& job) override;

 private:
  void FillMixBufWithSilence(uint32_t frames);
  void HandleAlsaError(snd_pcm_sframes_t code);
  void HandleAsError(snd_pcm_sframes_t code);
  void HandleAsUnderflow();

  snd_pcm_t* alsa_device_ = nullptr;
  snd_pcm_format_t alsa_format_;

  LinearTransform::Ratio frames_per_tick_;
  uint8_t silence_byte_;

  std::unique_ptr<uint8_t> mix_buf_;
  uint32_t mix_buf_frames_;

  bool primed_ = false;
  bool local_to_output_known_ = false;
  LinearTransform local_to_output_;
  uint32_t local_to_output_gen_ = MixJob::INVALID_GENERATION + 1;
  int64_t frames_sent_;
};

}  // namespace audio
}  // namespace media
}  // namespace mojo

#endif  // SERVICES_MEDIA_AUDIO_PLATFORM_LINUX_ALSA_OUTPUT_H_