opencv/modules/videoio/src/cap_images.cpp

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// Author: Nils Hasler <hasler@mpi-inf.mpg.de>
//
//         Max-Planck-Institut Informatik

//
// capture video from a sequence of images
// the filename when opening can either be a printf pattern such as
// video%04d.png or the first frame of the sequence i.e. video0001.png
//

#include "precomp.hpp"

#include "opencv2/core/utils/filesystem.hpp"

#if 0
#define CV_WARN(message)
#else
#define CV_WARN(message) CV_LOG_INFO(NULL, "CAP_IMAGES warning: %s (%s:%d)" << message)
#endif

using namespace cv;
namespace cv {

class CvCapture_Images : public CvCapture
{
public:
    CvCapture_Images()
    {
        currentframe = firstframe = 0;
        length = 0;
        frame = NULL;
        grabbedInOpen = false;
    }

    virtual ~CvCapture_Images() CV_OVERRIDE
    {
        close();
    }

    virtual bool open(const char* _filename);
    virtual void close();
    virtual double getProperty(int) const CV_OVERRIDE;
    virtual bool setProperty(int, double) CV_OVERRIDE;
    virtual bool grabFrame() CV_OVERRIDE;
    virtual IplImage* retrieveFrame(int) CV_OVERRIDE;

    int getCaptureDomain() /*const*/ CV_OVERRIDE { return cv::CAP_IMAGES; }
protected:
    std::string filename_pattern; // actually a printf-pattern
    unsigned currentframe;
    unsigned firstframe; // number of first frame
    unsigned length; // length of sequence

    IplImage* frame;
    bool grabbedInOpen;
};


void CvCapture_Images::close()
{
    currentframe = firstframe = 0;
    length = 0;
    cvReleaseImage(&frame);
}


bool CvCapture_Images::grabFrame()
{
    cv::String filename = cv::format(filename_pattern.c_str(), (int)(firstframe + currentframe));
    CV_Assert(!filename.empty());

    if (grabbedInOpen)
    {
        grabbedInOpen = false;
        ++currentframe;

        return frame != NULL;
    }

    cvReleaseImage(&frame);
    frame = cvLoadImage(filename.c_str(), CV_LOAD_IMAGE_UNCHANGED);
    if (frame)
        currentframe++;

    return frame != NULL;
}

IplImage* CvCapture_Images::retrieveFrame(int)
{
    return grabbedInOpen ? NULL : frame;
}

double CvCapture_Images::getProperty(int id) const
{
    switch(id)
    {
    case CV_CAP_PROP_POS_MSEC:
        CV_WARN("collections of images don't have framerates");
        return 0;
    case CV_CAP_PROP_POS_FRAMES:
        return currentframe;
    case CV_CAP_PROP_FRAME_COUNT:
        return length;
    case CV_CAP_PROP_POS_AVI_RATIO:
        return (double)currentframe / (double)(length - 1);
    case CV_CAP_PROP_FRAME_WIDTH:
        return frame ? frame->width : 0;
    case CV_CAP_PROP_FRAME_HEIGHT:
        return frame ? frame->height : 0;
    case CV_CAP_PROP_FPS:
        CV_WARN("collections of images don't have framerates");
        return 1;
    case CV_CAP_PROP_FOURCC:
        CV_WARN("collections of images don't have 4-character codes");
        return 0;
    }
    return 0;
}

bool CvCapture_Images::setProperty(int id, double value)
{
    switch(id)
    {
    case CV_CAP_PROP_POS_MSEC:
    case CV_CAP_PROP_POS_FRAMES:
        if(value < 0) {
            CV_WARN("seeking to negative positions does not work - clamping");
            value = 0;
        }
        if(value >= length) {
            CV_WARN("seeking beyond end of sequence - clamping");
            value = length - 1;
        }
        currentframe = cvRound(value);
        if (currentframe != 0)
            grabbedInOpen = false; // grabbed frame is not valid anymore
        return true;
    case CV_CAP_PROP_POS_AVI_RATIO:
        if(value > 1) {
            CV_WARN("seeking beyond end of sequence - clamping");
            value = 1;
        } else if(value < 0) {
            CV_WARN("seeking to negative positions does not work - clamping");
            value = 0;
        }
        currentframe = cvRound((length - 1) * value);
        if (currentframe != 0)
            grabbedInOpen = false; // grabbed frame is not valid anymore
        return true;
    }
    CV_WARN("unknown/unhandled property");
    return false;
}

static
std::string icvExtractPattern(const std::string& filename, unsigned *offset)
{
    size_t len = filename.size();
    CV_Assert(!filename.empty());
    CV_Assert(offset);

    *offset = 0;

    // check whether this is a valid image sequence filename
    std::string::size_type pos = filename.find('%');
    if (pos != std::string::npos)
    {
        pos++; CV_Assert(pos < len);
        if (filename[pos] == '0') // optional zero prefix
        {
            pos++; CV_Assert(pos < len);
        }
        if (filename[pos] >= '1' && filename[pos] <= '9') // optional numeric size (1..9) (one symbol only)
        {
            pos++; CV_Assert(pos < len);
        }
        if (filename[pos] == 'd' || filename[pos] == 'u')
        {
            pos++;
            if (pos == len)
                return filename;  // end of string '...%5d'
            CV_Assert(pos < len);
            if (filename.find('%', pos) == std::string::npos)
                return filename;  // no more patterns
            CV_Error_(Error::StsBadArg, ("CAP_IMAGES: invalid multiple patterns: %s", filename.c_str()));
        }
        CV_Error_(Error::StsBadArg, ("CAP_IMAGES: error, expected '0?[1-9][du]' pattern, got: %s", filename.c_str()));
    }
    else // no pattern filename was given - extract the pattern
    {
        pos = filename.rfind('/');
#ifdef _WIN32
        if (pos == std::string::npos)
            pos = filename.rfind('\\');
#endif
        if (pos != std::string::npos)
            pos++;
        else
            pos = 0;

        while (pos < len && !isdigit(filename[pos])) pos++;

        if (pos == len)
        {
            CV_Error_(Error::StsBadArg, ("CAP_IMAGES: can't find starting number (in the name of file): %s", filename.c_str()));
        }

        std::string::size_type pos0 = pos;

        const int64_t max_number = 1000000000;
        CV_Assert(max_number < INT_MAX); // offset is 'int'

        int number_str_size = 0;
        uint64_t number = 0;
        while (pos < len && isdigit(filename[pos]))
        {
            char ch = filename[pos];
            number = (number * 10) + (uint64_t)((int)ch - (int)'0');
            CV_Assert(number < max_number);
            number_str_size++;
            CV_Assert(number_str_size <= 64);  // don't allow huge zero prefixes
            pos++;
        }
        CV_Assert(number_str_size > 0);

        *offset = (int)number;

        std::string result;
        if (pos0 > 0)
            result += filename.substr(0, pos0);
        result += cv::format("%%0%dd", number_str_size);
        if (pos < len)
            result += filename.substr(pos);
        CV_LOG_INFO(NULL, "Pattern: " << result << " @ " << number);
        return result;
    }
}


bool CvCapture_Images::open(const char * _filename)
{
    unsigned offset = 0;
    close();

    CV_Assert(_filename);
    filename_pattern = icvExtractPattern(_filename, &offset);
    CV_Assert(!filename_pattern.empty());

    // determine the length of the sequence
    for (length = 0; ;)
    {
        cv::String filename = cv::format(filename_pattern.c_str(), (int)(offset + length));
        if (!utils::fs::exists(filename))
        {
            if (length == 0 && offset == 0) // allow starting with 0 or 1
            {
                offset++;
                continue;
            }
            break;
        }

        if (!cvHaveImageReader(filename.c_str()))
        {
            CV_LOG_INFO(NULL, "CAP_IMAGES: Stop scanning. Can't read image file: " << filename);
            break;
        }

        length++;
    }

    if (length == 0)
    {
        close();
        return false;
    }

    firstframe = offset;

    // grab frame to enable properties retrieval
    bool grabRes = grabFrame();
    grabbedInOpen = true;
    currentframe = 0;

    return grabRes;
}


CvCapture* cvCreateFileCapture_Images(const char * filename)
{
    CvCapture_Images* capture = new CvCapture_Images;

    try
    {
        if (capture->open(filename))
            return capture;
        delete capture;
    }
    catch (...)
    {
        delete capture;
        throw;
    }

    return NULL;
}

//
//
// image sequence writer
//
//
class CvVideoWriter_Images CV_FINAL : public CvVideoWriter
{
public:
    CvVideoWriter_Images()
    {
        currentframe = 0;
    }
    virtual ~CvVideoWriter_Images() { close(); }

    virtual bool open( const char* _filename );
    virtual void close();
    virtual bool setProperty( int, double ); // FIXIT doesn't work: IVideoWriter interface only!
    virtual bool writeFrame( const IplImage* ) CV_OVERRIDE;

    int getCaptureDomain() const CV_OVERRIDE { return cv::CAP_IMAGES; }
protected:
    std::string filename_pattern;
    unsigned currentframe;
    std::vector<int> params;
};

bool CvVideoWriter_Images::writeFrame( const IplImage* image )
{
    CV_Assert(!filename_pattern.empty());
    cv::String filename = cv::format(filename_pattern.c_str(), (int)currentframe);
    CV_Assert(!filename.empty());

    std::vector<int> image_params = params;
    image_params.push_back(0); // append parameters 'stop' mark
    image_params.push_back(0);
    int ret = cvSaveImage(filename.c_str(), image, &image_params[0]);

    currentframe++;

    return ret > 0;
}

void CvVideoWriter_Images::close()
{
    currentframe = 0;
    params.clear();
}


bool CvVideoWriter_Images::open( const char* _filename )
{
    unsigned offset = 0;
    close();

    CV_Assert(_filename);
    filename_pattern = icvExtractPattern(_filename, &offset);
    CV_Assert(!filename_pattern.empty());

    cv::String filename = cv::format(filename_pattern.c_str(), (int)currentframe);
    if (!cvHaveImageWriter(filename.c_str()))
    {
        close();
        return false;
    }

    currentframe = offset;
    params.clear();
    return true;
}


bool CvVideoWriter_Images::setProperty( int id, double value )
{
    if (id >= cv::CAP_PROP_IMAGES_BASE && id < cv::CAP_PROP_IMAGES_LAST)
    {
        params.push_back( id - cv::CAP_PROP_IMAGES_BASE );
        params.push_back( static_cast<int>( value ) );
        return true;
    }
    return false; // not supported
}


CvVideoWriter* cvCreateVideoWriter_Images( const char* filename )
{
    CvVideoWriter_Images *writer = new CvVideoWriter_Images;

    try
    {
        if (writer->open(filename))
            return writer;
        delete writer;
    }
    catch (...)
    {
        delete writer;
        throw;
    }

    return 0;
}


} // namespace