opencv/modules/videoio/src/videoio_c.cpp

// This file is part of OpenCV project.
// It is subject to the license terms in the LICENSE file found in the top-level directory
// of this distribution and at http://opencv.org/license.html.

#include "precomp.hpp"

#include "videoio_registry.hpp"

using namespace cv;

// Legacy C-like API

CV_IMPL CvCapture* cvCreateCameraCapture(int index)
{
    // interpret preferred interface (0 = autodetect)
    int apiPreference = (index / 100) * 100;
    if (apiPreference)
    {
        index %= 100;
    }

    const std::vector<VideoBackendInfo> backends = cv::videoio_registry::getAvailableBackends_CaptureByIndex();
    for (size_t i = 0; i < backends.size(); i++)
    {
        const VideoBackendInfo& info = backends[i];
        if (apiPreference == CAP_ANY || apiPreference == info.id)
        {
            CvCapture* capture = NULL;
            Ptr<IVideoCapture> icap; // unused
            VideoCapture_create(capture, icap, info.id, index);
            if (capture)
            {
                return capture;
            }
            if (!icap.empty())
            {
                CV_LOG_WARNING(NULL, "cvCreateFileCaptureWithPreference: backend " << info.name << " doesn't support legacy API anymore.")
            }
        }
    }
    return NULL;
}

CV_IMPL CvCapture* cvCreateFileCaptureWithPreference(const char* filename, int apiPreference)
{
    const std::vector<VideoBackendInfo> backends = cv::videoio_registry::getAvailableBackends_CaptureByFilename();
    for (size_t i = 0; i < backends.size(); i++)
    {
        const VideoBackendInfo& info = backends[i];
        if (apiPreference == CAP_ANY || apiPreference == info.id)
        {
            CvCapture* capture = NULL;
            Ptr<IVideoCapture> icap; // unused
            VideoCapture_create(capture, icap, info.id, filename);
            if (capture)
            {
                return capture;
            }
            if (!icap.empty())
            {
                CV_LOG_WARNING(NULL, "cvCreateFileCaptureWithPreference: backend " << info.name << " doesn't support legacy API anymore.")
            }
        }
    }
    return NULL;
}

CV_IMPL CvCapture* cvCreateFileCapture(const char * filename)
{
    return cvCreateFileCaptureWithPreference(filename, CAP_ANY);
}

CV_IMPL CvVideoWriter* cvCreateVideoWriter(const char* filename, int fourcc,
                                           double fps, CvSize frameSize, int is_color)
{
    const std::vector<VideoBackendInfo> backends = cv::videoio_registry::getAvailableBackends_Writer();
    for (size_t i = 0; i < backends.size(); i++)
    {
        const VideoBackendInfo& info = backends[i];
        {
            CvVideoWriter* writer_ = NULL;
            Ptr<IVideoWriter> iwriter;  // unused
            VideoWriter_create(writer_, iwriter, info.id, filename, fourcc, fps, frameSize, is_color != 0);
            if (writer_)
            {
                return writer_;
            }
            if (!iwriter.empty())
            {
                CV_LOG_WARNING(NULL, "cvCreateVideoWriter: backend " << info.name << " doesn't support legacy API anymore.")
            }
        }
    }
    return NULL;
}

CV_IMPL int cvWriteFrame(CvVideoWriter* writer, const IplImage* image)
{
    return writer ? writer->writeFrame(image) : 0;
}

CV_IMPL void cvReleaseVideoWriter(CvVideoWriter** pwriter)
{
    if( pwriter && *pwriter )
    {
        delete *pwriter;
        *pwriter = 0;
    }
}

CV_IMPL void cvReleaseCapture(CvCapture** pcapture)
{
    if (pcapture && *pcapture)
    {
        delete *pcapture;
        *pcapture = 0;
    }
}

CV_IMPL IplImage* cvQueryFrame(CvCapture* capture)
{
    if (!capture)
        return 0;
    if (!capture->grabFrame())
        return 0;
    return capture->retrieveFrame(0);
}

CV_IMPL int cvGrabFrame(CvCapture* capture)
{
    return capture ? capture->grabFrame() : 0;
}

CV_IMPL IplImage* cvRetrieveFrame(CvCapture* capture, int idx)
{
    return capture ? capture->retrieveFrame(idx) : 0;
}

CV_IMPL double cvGetCaptureProperty(CvCapture* capture, int id)
{
    return capture ? capture->getProperty(id) : 0;
}

CV_IMPL int cvSetCaptureProperty(CvCapture* capture, int id, double value)
{
    return capture ? capture->setProperty(id, value) : 0;
}

CV_IMPL int cvGetCaptureDomain(CvCapture* capture)
{
    return capture ? capture->getCaptureDomain() : 0;
}