videoreader.h

#ifndef LIBCVD_VIDEOREADER_H
#define LIBCVD_VIDEOREADER_H

#include "image.h"
#include "image_ref.h"
#include "rgba.h"
#include "videoffmpeg.h"

#include <libavutil/rational.h>

#include <cstdint>
#include <memory>
#include <string>
#include <utility>

namespace CVD
{
namespace internal
{
    class Scaler;
}

// Reads video files using FFmpeg as RGBA frames.
class VideoReader
{
    public:
    VideoReader(const std::string& filename, int threads = 1);
    ~VideoReader();

    // Convert an FFmpeg timestamp from the video stream to seconds since the start of the video.
    double timebase_to_seconds(std::int64_t pts) const;
    // Get the timebase of the video.
    AVRational timebase() const;
    // Get the size of each video frame, in pixels.
    ImageRef size() const;
    // Get the frame rate of the video.
    AVRational frame_rate() const;
    // Get the duration of the video, in the video timebase.
    std::int64_t duration() const;
    // Read the next frame from the video as an RGBA frame and timestamp in the video timebase.
    // Returns an empty image if there are no more frames in the video.
    std::pair<Image<Rgba<std::uint8_t>>, std::int64_t> get_frame();

    private:
    std::unique_ptr<AVFormatContext, internal::AVFormatContextCloser> m_format_context;
    std::unique_ptr<AVCodecContext, internal::AVCodecContextCloser> m_codec_context;
    std::unique_ptr<internal::Scaler> m_scaler;
    std::unique_ptr<AVFrame, internal::AVFrameDeleter> m_raw_frame;
    int m_stream_index = -1;
};

}

#endif