Playing video by long key press using open cv - c++

Question

I need to make small video player with OpenCV, which have to support the following functionality. Key 'p' on keyboard - pause/unpause, 'q' - exit, left and right arrow keys - play video frame by frame straight and reverse when it is paused. So the problem is when I try to show video with high quality and I hold arrow key for several seconds it does not run, but freeze and then jump to current frame after I release key. I tried to fix this with adding this_thread::sleep after cv::imshow() to give time to draw, but it did not help at all. So here is the code. Also, I have some reasons to use boost instead of C++11, so it is ok.
main.cpp
#include "VideoPlayer.hpp"
#include <iostream>
int main(int argc, char *argv[])
{
if (argc < 2) {
std::cerr << "Video file full name required as argument." << std::endl;
}
VideoPlayer vp(argv[1]);
if (!vp.play())
return 1;
return 0;
}
VideoPlayer.hpp
#pragma once
#include <opencv/cxcore.hpp>
#include <opencv/highgui.h>
#include <string>
class VideoPlayer
{
public:
VideoPlayer(const std::string &video, const std::string &windowName = "Output window",
unsigned int delay = 30);
bool play();
private:
cv::VideoCapture videoCapture_;
std::string windowName_;
unsigned int delay_;
private:
bool processKey(int key);
void setFrame(int frameNum);
};
VideoPlayer.cpp
#include "VideoPlayer.hpp"
#include <iostream>
#include <boost/date_time/posix_time/posix_time.hpp>
#include <boost/thread/thread.hpp>
VideoPlayer::VideoPlayer(const std::string &video, const std::string &windowName,
unsigned int delay)
: videoCapture_(video)
, windowName_(windowName)
, delay_(delay)
{}
bool VideoPlayer::play()
{
if (!videoCapture_.isOpened()) {
std::cerr << "Unable to open video." << std::endl;
return false;
}
cv::namedWindow(windowName_);
for (;;) {
cv::Mat frame;
videoCapture_ >> frame;
cv::imshow(windowName_, frame);
int key = cv::waitKey(delay_);
if (processKey(key))
break;
}
return true;
}
bool VideoPlayer::processKey(int key)
{
if (key == 'p') {
for (;;) {
int pausedKey = cv::waitKey(0);
if (pausedKey == 'p') {
break;
} else if (pausedKey == 'q') {
return true;
} else if (pausedKey == 65363) {
int frameNum = videoCapture_.get(CV_CAP_PROP_POS_FRAMES);
setFrame(frameNum);
} else if (pausedKey == 65361) {
int frameNum = videoCapture_.get(CV_CAP_PROP_POS_FRAMES);
setFrame(frameNum - 2);
}
}
} else if (key == 'q') {
return true;
}
return false;
}
void VideoPlayer::setFrame(int frameNum)
{
if (frameNum > 0 && frameNum < videoCapture_.get(CV_CAP_PROP_FRAME_COUNT)) {
std::cerr << frameNum << std::endl;
videoCapture_.set(CV_CAP_PROP_POS_FRAMES, frameNum);
cv::Mat frame;
videoCapture_ >> frame;
cv::imshow(windowName_, frame);
boost::this_thread::sleep(boost::posix_time::milliseconds(10));
}
}
I also created a multithreading implementation with buffer based on std::queue with lock, but it didn't solve the problem. And I tried to use boost::lockfree::queue, but I could not manage to finish it because of some strange behavior. I will share this code later, if it is necessary.
So, if somebody knows some good practice, how to avoid this problem, help me please.
EDIT:
Replacing boost::this_thread::sleep(boost::posix_time::milliseconds(10)); with cv::waitKey(0) is bad, because is makes me to do two short presses on arrow key to change one frame, and it does not help, because holding key skips it very fast. So the following code helped, but it is too strange and it is necessary to select times each for each video.
void VideoPlayer::setFrame(int frameNum)
{
if (frameNum > 0 && frameNum < videoCapture_.get(CV_CAP_PROP_FRAME_COUNT)) {
std::cerr << frameNum << std::endl;
videoCapture_.set(CV_CAP_PROP_POS_FRAMES, frameNum);
cv::Mat frame;
videoCapture_ >> frame;
cv::imshow(windowName_, frame);
int times = 7;
for (int i = 0; i < times; i++)
cv::waitKey(10);
}
}
Also, I'm unable to use Qt or something else, only C++03 with boost and OpenCV.
I think I need some trick to make cv::waitKey(time) wait fortime whether any key pressed or not.