Merge pull request #25349 from gursimarsingh:videocapture_samples_cpp

combined videocapture and videowriter samples for cleanup
2026-07-29 07:13:02 +04:00 · 2024-10-28 12:27:54 +05:30
parent 331d327760
commit f217656916
8 changed files with 212 additions and 299 deletions
@@ -0,0 +1,118 @@
+/**
+  @file videowriter.cpp
+  @brief A sample for VideoWriter and VideoCapture with options to specify video codec, fps and resolution
+  @date April 05, 2024
+*/
+
+
+#include <opencv2/core.hpp>
+#include <opencv2/videoio.hpp>
+#include <opencv2/highgui.hpp>
+#include <opencv2/imgproc.hpp>
+#include <iostream>
+#include <map>
+
+using namespace cv;
+using namespace std;
+
+inline map<string, int> fourccByCodec() {
+    map<string, int> res;
+    res["h264"] = VideoWriter::fourcc('H', '2', '6', '4');
+    res["h265"] = VideoWriter::fourcc('H', 'E', 'V', 'C');
+    res["mpeg2"] = VideoWriter::fourcc('M', 'P', 'E', 'G');
+    res["mpeg4"] = VideoWriter::fourcc('M', 'P', '4', '2');
+    res["mjpeg"] = VideoWriter::fourcc('M', 'J', 'P', 'G');
+    res["vp8"] = VideoWriter::fourcc('V', 'P', '8', '0');
+    return res;
+}
+
+// Function to parse resolution string "WxH"
+static Size parseResolution(const string& resolution) {
+    stringstream ss(resolution);
+    int width, height;
+    char delimiter;
+
+    ss >> width >> delimiter >> height;
+
+    if (ss.fail() || delimiter != 'x') {
+        throw runtime_error("Invalid resolution format. Please provide in WxH format.");
+    }
+
+    return Size(width, height);
+}
+
+
+int main(int argc, char** argv) {
+    const String keys =
+        "{help h usage ? |      | Print help message   }"
+        "{fps           |30    | fix frame per second for encoding (supported: fps > 0)   }"
+        "{codec         |mjpeg | Supported codecs depend on OpenCV Configuration. Try one of 'h264', 'h265', 'mpeg2', 'mpeg4', 'mjpeg', 'vp8' }"
+        "{resolution    |1280x720 | Video resolution in WxH format, (e.g., '1920x1080') }"
+        "{output_filepath    | output.avi | Path to the output video file}";
+
+    CommandLineParser parser(argc, argv, keys);
+    parser.about("Video Capture and Write with codec and resolution options");
+
+    if (parser.has("help")) {
+        parser.printMessage();
+        return 0;
+    }
+
+    double fps = parser.get<double>("fps");
+    string codecStr = parser.get<string>("codec");
+    string resolutionStr = parser.get<string>("resolution");
+    string outputFilepath = parser.get<string>("output_filepath");
+
+    auto codecMap = fourccByCodec();
+
+    if (codecMap.find(codecStr) == codecMap.end()) {
+        cerr << "Invalid codec" << endl;
+        return -1;
+    }
+
+    int codec = codecMap[codecStr];
+    Size resolution = parseResolution(resolutionStr);
+
+    // Video Capture
+    VideoCapture cap(0);
+    if (!cap.isOpened()) {
+        cerr << "ERROR! Unable to open camera\n";
+        return -1;
+    }
+
+    cout << "Selected FPS: " << fps << endl;
+    cout << "Selected Codec: " << codecStr << endl;
+    cout << "Selected Resolution: " << resolutionStr << " (" << resolution.width << "x" << resolution.height << ")" << endl;
+
+    // Set up VideoWriter
+    VideoWriter writer(outputFilepath, codec, fps, resolution, true); // Assuming color video
+    if (!writer.isOpened()) {
+        cerr << "Could not open the output video file for write\n";
+        return -1;
+    }
+
+    cout << "Writing video file: " << outputFilepath << endl
+         << "Press any key to terminate" << endl;
+
+    Mat frame, resizedFrame;
+    for (;;) {
+        // Capture frame
+        if (!cap.read(frame) || frame.empty()) {
+            break;
+        }
+
+        // Resize frame to desired resolution
+        resize(frame, resizedFrame, resolution);
+
+        // Write resized frame to video
+        writer.write(resizedFrame);
+
+        // Show live
+        imshow("Live", resizedFrame);
+        if (waitKey(5) >= 0) break;
+    }
+
+    // VideoWriter and VideoCapture are automatically closed by their destructors
+
+    return 0;
+}