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#include "precomp.hpp"

using namespace cv;
using namespace cv::cuda;
using namespace cv::cudacodec;

#ifndef HAVE_NVCUVID

Ptr<VideoReader> cv::cudacodec::createVideoReader(const String&) { throw_no_cuda(); return Ptr<VideoReader>(); }
Ptr<VideoReader> cv::cudacodec::createVideoReader(const Ptr<RawVideoSource>&) { throw_no_cuda(); return Ptr<VideoReader>(); }

#else // HAVE_NVCUVID

namespace cv { namespace cuda { namespace device
{
    void NV12_to_RGB(const PtrStepb decodedFrame, PtrStepSz<uint> interopFrame, cudaStream_t stream = 0);
}}}

namespace
{
    class VideoReaderImpl : public VideoReader
    {
    public:
        explicit VideoReaderImpl(const Ptr<detail::VideoSource>& source);
        ~VideoReaderImpl();

        bool nextFrame(OutputArray frame);

        FormatInfo format() const;

    private:
        Ptr<detail::VideoSource> videoSource_;

        Ptr<detail::FrameQueue> frameQueue_;
        Ptr<detail::VideoDecoder> videoDecoder_;
        Ptr<detail::VideoParser> videoParser_;

        CUvideoctxlock lock_;

        std::deque< std::pair<CUVIDPARSERDISPINFO, CUVIDPROCPARAMS> > frames_;
    };

    FormatInfo VideoReaderImpl::format() const
    {
        return videoSource_->format();
    }

    VideoReaderImpl::VideoReaderImpl(const Ptr<detail::VideoSource>& source) :
        videoSource_(source),
        lock_(0)
    {
        // init context
        GpuMat temp(1, 1, CV_8UC1);
        temp.release();

        CUcontext ctx;
        cuSafeCall( cuCtxGetCurrent(&ctx) );
        cuSafeCall( cuvidCtxLockCreate(&lock_, ctx) );

        frameQueue_ = new detail::FrameQueue;
        videoDecoder_ = new detail::VideoDecoder(videoSource_->format(), lock_);
        videoParser_ = new detail::VideoParser(videoDecoder_, frameQueue_);

        videoSource_->setVideoParser(videoParser_);
        videoSource_->start();
    }

    VideoReaderImpl::~VideoReaderImpl()
    {
        frameQueue_->endDecode();
        videoSource_->stop();
    }

    class VideoCtxAutoLock
    {
    public:
        VideoCtxAutoLock(CUvideoctxlock lock) : m_lock(lock) { cuSafeCall( cuvidCtxLock(m_lock, 0) ); }
        ~VideoCtxAutoLock() { cuvidCtxUnlock(m_lock, 0); }

    private:
        CUvideoctxlock m_lock;
    };

    void cudaPostProcessFrame(const GpuMat& decodedFrame, OutputArray _outFrame, int width, int height)
    {
        using namespace cv::cuda::device;

        // Final Stage: NV12toARGB color space conversion

        _outFrame.create(height, width, CV_8UC4);
        GpuMat outFrame = _outFrame.getGpuMat();

        NV12_to_RGB(decodedFrame, outFrame);
    }

    bool VideoReaderImpl::nextFrame(OutputArray frame)
    {
        if (videoSource_->hasError() || videoParser_->hasError())
            CV_Error(Error::StsUnsupportedFormat, "Unsupported video source");

        if (!videoSource_->isStarted() || frameQueue_->isEndOfDecode())
            return false;

        if (frames_.empty())
        {
            CUVIDPARSERDISPINFO displayInfo;

            for (;;)
            {
                if (frameQueue_->dequeue(displayInfo))
                    break;

                if (videoSource_->hasError() || videoParser_->hasError())
                    CV_Error(Error::StsUnsupportedFormat, "Unsupported video source");

                if (frameQueue_->isEndOfDecode())
                    return false;

                // Wait a bit
                detail::Thread::sleep(1);
            }

            bool isProgressive = displayInfo.progressive_frame != 0;
            const int num_fields = isProgressive ? 1 : 2 + displayInfo.repeat_first_field;

            for (int active_field = 0; active_field < num_fields; ++active_field)
            {
                CUVIDPROCPARAMS videoProcParams;
                std::memset(&videoProcParams, 0, sizeof(CUVIDPROCPARAMS));

                videoProcParams.progressive_frame = displayInfo.progressive_frame;
                videoProcParams.second_field      = active_field;
                videoProcParams.top_field_first   = displayInfo.top_field_first;
                videoProcParams.unpaired_field    = (num_fields == 1);

                frames_.push_back(std::make_pair(displayInfo, videoProcParams));
            }
        }

        if (frames_.empty())
            return false;

        std::pair<CUVIDPARSERDISPINFO, CUVIDPROCPARAMS> frameInfo = frames_.front();
        frames_.pop_front();

        {
            VideoCtxAutoLock autoLock(lock_);

            // map decoded video frame to CUDA surface
            GpuMat decodedFrame = videoDecoder_->mapFrame(frameInfo.first.picture_index, frameInfo.second);

            // perform post processing on the CUDA surface (performs colors space conversion and post processing)
            // comment this out if we inclue the line of code seen above
            cudaPostProcessFrame(decodedFrame, frame, videoDecoder_->targetWidth(), videoDecoder_->targetHeight());

            // unmap video frame
            // unmapFrame() synchronizes with the VideoDecode API (ensures the frame has finished decoding)
            videoDecoder_->unmapFrame(decodedFrame);
        }

        // release the frame, so it can be re-used in decoder
        if (frames_.empty())
            frameQueue_->releaseFrame(frameInfo.first);

        return true;
    }
}

Ptr<VideoReader> cv::cudacodec::createVideoReader(const String& filename)
{
    CV_Assert( !filename.empty() );

    Ptr<detail::VideoSource> videoSource;

    try
    {
        videoSource = new detail::CuvidVideoSource(filename);
    }
    catch (...)
    {
        Ptr<RawVideoSource> source(new detail::FFmpegVideoSource(filename));
        videoSource = new detail::RawVideoSourceWrapper(source);
    }

    return new VideoReaderImpl(videoSource);
}

Ptr<VideoReader> cv::cudacodec::createVideoReader(const Ptr<RawVideoSource>& source)
{
    Ptr<detail::VideoSource> videoSource(new detail::RawVideoSourceWrapper(source));
    return new VideoReaderImpl(videoSource);
}

#endif // HAVE_NVCUVID