Create C++ version

cpp/include/chicken_counter/video_writer.hpp

@@ -0,0 +1,66 @@
+#pragma once
+
+#include <cstdint>
+#include <filesystem>
+#include <iostream>
+#include <string>
+#include <vector>
+
+#include <opencv2/videoio.hpp>
+
+namespace cc {
+
+inline cv::VideoWriter make_video_writer(
+    const std::string& path,
+    const cv::Size& frame_size,
+    double fps,
+    const std::string& encoder = "auto",
+    int output_bitrate_kbps = 4000,
+    const std::vector<std::string>& codec_preference = {})
+{
+    namespace fs = std::filesystem;
+    fs::create_directories(fs::path(path).parent_path());
+
+    int bitrate_bps = std::max(1, output_bitrate_kbps) * 1000;
+    auto codecs = codec_preference.empty()
+        ? std::vector<std::string>{"avc1", "mp4v", "H264"}
+        : codec_preference;
+
+    if (encoder == "auto" || encoder == "gstreamer") {
+        int fps_int = std::max(1, static_cast<int>(std::round(fps)));
+        std::string pipeline =
+            "appsrc ! video/x-raw, format=BGR ! "
+            "video/x-raw,width=" + std::to_string(frame_size.width) +
+            ",height=" + std::to_string(frame_size.height) +
+            ",framerate=" + std::to_string(fps_int) + "/1 ! "
+            "videoconvert ! nvvidconv ! "
+            "video/x-raw(memory:NVMM),format=NV12 ! "
+            "nvv4l2h264enc bitrate=" + std::to_string(bitrate_bps) +
+            " insert-sps-pps=true ! "
+            "h264parse ! mp4mux ! filesink location=" + path;
+
+        cv::VideoWriter writer(pipeline, cv::CAP_GSTREAMER, 0, fps, frame_size, true);
+        if (writer.isOpened()) {
+            std::cerr << "[video] opened GStreamer hardware encoder (bitrate="
+                      << output_bitrate_kbps << " kbps)\n";
+            return writer;
+        }
+        writer.release();
+        if (encoder == "gstreamer")
+            throw std::runtime_error("GStreamer video writer failed for: " + path);
+    }
+
+    for (const auto& codec : codecs) {
+        int fourcc = cv::VideoWriter::fourcc(codec[0], codec[1], codec[2], codec[3]);
+        cv::VideoWriter writer(path, fourcc, fps, frame_size);
+        if (writer.isOpened()) {
+            std::cerr << "[video] opened OpenCV encoder (codec=" << codec << ")\n";
+            return writer;
+        }
+        writer.release();
+    }
+
+    throw std::runtime_error("Unable to open video writer: " + path);
+}
+
+} // namespace cc