recorder.h

/****************************************************************************
 * Copyright (c) 2014, Joel Kivelä, Erkki Koskenkorva, Oskari Leppäaho,
 * Mika Lehtinen and Petri Partanen.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name of the copyright holders nor the names of its
 *       contributors may be used to endorse or promote products derived from
 *       this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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****************************************************************************/
#ifndef RECORDER_H
#define RECORDER_H

#include <condition_variable>
#include <chrono>
#include <deque>
#include <mutex>
#include <thread>

#include "../common.h"

namespace cavapa_gui
{
struct RecorderStats
{
    unsigned int missed_frames;

    unsigned int written_frames;
};

// Empty statistics that can be used for zeroing.
static const RecorderStats EMPTY_RECORDER_STATS = {0, 0};

class Recorder {
public:
    Recorder() {}
    ~Recorder();

    DISALLOW_COPY_AND_ASSIGN(Recorder);

    unsigned int countBuffered();

    static void detach(std::unique_ptr<Recorder>&& ptr)
        { detached_recorders.push_back(std::move(ptr)); }

    unsigned int getMissedFrames();

    unsigned int getRecordedFrames();

    bool isOpen() { return is_open; }

    bool isTerminated();

    bool open(const std::string& filename, int fourcc,
              double fps, cv::Size frameSize, bool isColor = true);

    RecorderStats push(const cv::Mat& image);

    bool repush();

    void stop();

private:
    enum class RecorderStatus { ALIVE, STOP, TERMINATE };

    inline bool fetch(std::unique_lock<std::mutex>& guard);

    static void flushDetached();

    inline cv::Mat pop();

    inline void setStatus(RecorderStatus new_status);

    void work();

    bool is_open = false; // For the main thread to use without a mutex!

    // These class members are accessed only with a mutex:
    std::deque<cv::Mat> buffer; // Buffer for images.
    std::mutex buffer_mutex;    // General buffer mutex.
    cv::Mat latest_image;       // Will hold the last image for repushing.
    RecorderStats statistics = EMPTY_RECORDER_STATS;
    RecorderStatus status = RecorderStatus::ALIVE; // Current status
    std::condition_variable wake_worker;// Buffer status change signal
    std::unique_ptr<std::thread> worker = nullptr; // Thread for writing

    // OpenCV writer, the main thread should not access this if the
    // worker thread exists! No mutex is used for this, in order to retrieve
    // without the main thread waiting.
    std::unique_ptr<cv::VideoWriter> writer = nullptr;

    // List of terminating recorders.
    static std::vector<std::unique_ptr<Recorder>> detached_recorders;
};
} // namespace

#endif // RECORDER_H