audio_stream.h

/*
 * Copyright 2025 LiveKit
 *
 * 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.
 */
 
#pragma once
 
#include <condition_variable>
#include <cstdint>
#include <deque>
#include <memory>
#include <mutex>
#include <optional>
#include <string>
 
#include "livekit/audio_frame.h"
#include "livekit/ffi_handle.h"
#include "livekit/participant.h"
#include "livekit/track.h"
#include "livekit/visibility.h"
 
namespace livekit {
 
namespace proto {
class FfiEvent;
}
 
// NOLINTBEGIN(bugprone-exception-escape)
// AudioFrame can throw in various places monitored by bugprone-exception-escape
// Suppressing for now, would require significant refactor to fix
 
struct AudioFrameEvent {
  AudioFrame frame; 
};
// NOLINTEND(bugprone-exception-escape)
 
class LIVEKIT_API AudioStream {
public:
  struct Options {
    std::size_t capacity{0};
 
    std::string noise_cancellation_module;
 
    std::string noise_cancellation_options_json;
  };
 
  static std::shared_ptr<AudioStream> fromTrack(const std::shared_ptr<Track>& track, const Options& options);
 
  static std::shared_ptr<AudioStream> fromParticipant(Participant& participant, TrackSource track_source,
                                                      const Options& options);
 
  virtual ~AudioStream();
 
  AudioStream(const AudioStream&) = delete;
  AudioStream& operator=(const AudioStream&) = delete;
  AudioStream(AudioStream&&) noexcept;
  AudioStream& operator=(AudioStream&&) noexcept;
 
  bool read(AudioFrameEvent& out_event);
 
  void close();
 
private:
  AudioStream() = default;
 
  void initFromTrack(const std::shared_ptr<Track>& track, const Options& options);
  void initFromParticipant(Participant& participant, TrackSource track_source, const Options& options);
 
  // FFI event handler (registered with FfiClient)
  void onFfiEvent(const proto::FfiEvent& event);
 
  // Queue helpers
  void pushFrame(AudioFrameEvent&& ev);
  void pushEos();
 
  mutable std::mutex mutex_;
  std::condition_variable cv_;
  std::deque<AudioFrameEvent> queue_;
  std::size_t capacity_{0};
  bool eof_{false};
  bool closed_{false};
 
  Options options_;
 
  // Underlying FFI audio stream handle
  FfiHandle stream_handle_;
 
  // Listener id registered on FfiClient
  std::int32_t listener_id_{0};
};
 
} // namespace livekit