Is it possible to crop raw video before extracting all the frames using OpenCV and C++?

The name of the pictureThe name of the pictureThe name of the pictureClash Royale CLAN TAG#URR8PPP

Is it possible to crop raw video before extracting all the frames using OpenCV and C++?



I want to crop a certain area of my raw video before extracting the frames. I don't want to use external cropping video software because I need the video to be raw for processing. Is it possible to crop a certain area before extraction ? I read about ROI for images, is it possible for video too ?



Here's my extraction code that's already working :


#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include <iostream>
#include <string>
#include <sstream>

using namespace cv;
using namespace std;
int c = 0;
string int2str(int &);

int main(int argc, char **argv)
string s;

VideoCapture cap("test_video.mov");
if (!cap.isOpened())

cout << "Cannot open the video file" << endl;
return -1;


double fps = cap.get(CV_CAP_PROP_FPS);

cout << "Frame per seconds : " << fps << endl;

namedWindow("MyVideo", CV_WINDOW_NORMAL);
resizeWindow("MyVideo", 600, 600);
while (1)

Mat frame;
Mat Gray_frame;
bool bSuccess = cap.read(frame);

if (!bSuccess)

cout << "Cannot read the frame from video file" << endl;
break;

s = int2str(c);
//cout<<("%dn",frame )<<endl;
c++;
imshow("MyVideo", frame);
imwrite("frame" + s + ".jpg", frame);
if (waitKey(30) == 27)

cout << "esc key is pressed by user" << endl;
break;



return 0;



string int2str(int &i)
string s;
stringstream ss(s);
ss << i;
return ss.str();



Still need to crop the video, any advice ?





What's wrong with setting the ROI after extraction?
– hkchengrex
11 hours ago





The video has a long duration with high fps, there will be thousands extracted images and setting the ROI after the extraction isn't really practical for me, it's too slow. I want to know if there's a way to crop the video first.
– Hiro
11 hours ago






As far as I know there is no way to crop video without reading. You can do it with external program before doing this with OpenCV. If it is too slow are you sure that this is the bottelneck of your solution?
– wdudzik
7 hours ago









By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service, privacy policy and cookie policy, and that your continued use of the website is subject to these policies.

Comments

Post a Comment

Popular posts from this blog

Executable numpy error

Image
Clash Royale CLAN TAG #URR8PPP Executable numpy error I'm trying to create an executable file for my code. I've already tried with cx_Freeze and with pyinstaller. Both gives me the same error, which is: "Missing required dependencies 0.format(missing_dependencies))" PS C:UsersGustavoDesktopbuildexe.win32-3.6> python AgendaOficial.py C:UsersGustavoAppDataLocalProgramsPythonPython36-32python.exe: can't open file 'AgendaOficial.py': [Errno 2] No such file or directory PS C:UsersGustavoDesktopbuildexe.win32-3.6> .AgendaOficial.exe Traceback (most recent call last): File "C:UsersGustavoAppDataLocalProgramsPythonPython36-32libsite-packagescx_Freezeinitscripts__startup__.py", line 14, in run module.run() File "C:UsersGustavoAppDataLocalProgramsPythonPython36-32libsite-packagescx_FreezeinitscriptsConsole.py", line 26, in run exec(code, m. dict ) File "AgendaOficial.py", line 8, in File "C:UsersGustavoAppDataLocal
Read more

PySpark count values by condition

Image
Clash Royale CLAN TAG #URR8PPP PySpark count values by condition I have a DataFrame, a snippet here: [['u1', 1], ['u2', 0]] basically one string ('f') and either a 1 or a 0 for second element ('is_fav'). What I need to do is grouping on the first field and counting the occurrences of 1s and 0s. I was hoping to do something like num_fav = count((col("is_fav") == 1)).alias("num_fav") num_nonfav = count((col("is_fav") == 0)).alias("num_nonfav") df.groupBy("f").agg(num_fav, num_nonfav) It does not work properly, I get in both cases the same result which amounts to the count for the items in the group, so the filter (whether it is a 1 or a 0) seems to be ignored. Does this depend on how count works? count 1 Answer 1 There is no filter here. Both col("is_fav") == 1 and col("is_fav") == 0) are just boolean expressions and count doesn't really care about their value as long a
Read more

Mass disable jenkins jobs

Image
Clash Royale CLAN TAG #URR8PPP Mass disable jenkins jobs Is it possible to disable a large number of Jenkins jobs in one go? I have a large number of jenkins job I need to disable. Visiting each job in turn and disbling is tedious. 2 Answers 2 https://wiki.jenkins-ci.org/display/JENKINS/Configuration+Slicing+Plugin That works beautifully install it go to http://your_jenkins.com:8080/slicing/jobdisabledbool/? By using configuration slicing plugin: By using this plugin easy to find out anything has enabled or disable jobs and timer separated jobs Manage Jenkins >Config slicing > select options By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service, privacy policy and cookie policy, and that your continued use of the website is subject to these policies.
Read more