Video can be recorded from images

doc/release_notes.md

@@ -289,7 +289,8 @@ OpenPose Library - Release Notes
     19. All bash scripts incorporate `#!/bin/bash` to tell the terminal that they are bash scripts.
     20. Added flag `--verbose` to plot the progress.
     21. Added find_package(Protobuf) to allow specific versions of Protobuf.
-    22. Examples do not end in core dumped if an OpenPose exception occurred, but it is rather closed returning -1.
+    22. Examples do not end in core dumped if an OpenPose exception occurred during initialization, but it is rather closed returning -1. However, it will still results in core dumped if the exception occurs during multi-threading execution.
+    23. Video (`--write_video`) can be generated from images (`--image_dir`), as long as they maintain the same resolution.
 2. Functions or parameters renamed:
     1. By default, python example `tutorial_developer/python_2_pose_from_heatmaps.py` was using 2 scales starting at -1x736, changed to 1 scale at -1x368.
     2. WrapperStructPose default parameters changed to match those of the OpenPose demo binary.

include/openpose/filestream/videoSaver.hpp

@@ -10,7 +10,7 @@ namespace op
     class OP_API VideoSaver
     {
     public:
-        VideoSaver(const std::string& videoSaverPath, const int cvFourcc, const double fps, const Point<int>& cvSize);
+        VideoSaver(const std::string& videoSaverPath, const int cvFourcc, const double fps);
 
         virtual ~VideoSaver();
 
@@ -24,7 +24,8 @@ namespace op
         const std::string mVideoSaverPath;
         const int mCvFourcc;
         const double mFps;
-        const Point<int> mCvSize;
+        Point<int> mCvSize;
+        bool mVideoStarted;
         cv::VideoWriter mVideoWriter;
         unsigned int mNumberImages;
 

include/openpose/wrapper/wrapperAuxiliary.hpp

@@ -651,7 +651,7 @@ namespace op
             if (!wrapperStructOutput.writeVideo.empty() || !wrapperStructOutput.writeBvh.empty())
             {
                 if (wrapperStructOutput.writeVideoFps <= 0
-                    && (producerSharedPtr == nullptr || producerSharedPtr->get(CV_CAP_PROP_FPS) <= 0))
+                    && (!oPProducer || producerSharedPtr->get(CV_CAP_PROP_FPS) <= 0))
                     error("The frame rate of the frames producer is unknown. Set `--write_video_fps` to your desired"
                           " FPS if you wanna record video (`--write_video`). E.g., if it is a folder of images, you"
                           " will have to know or guess the frame rate; if it is a webcam, you should use the OpenPose"
@@ -666,12 +666,8 @@ namespace op
                         error("Video file can only be recorded inside `wrapper/wrapper.hpp` if the producer"
                               " is one of the default ones (e.g., video, webcam, ...).",
                               __LINE__, __FUNCTION__, __FILE__);
-                    if (finalOutputSize.x <= 0 || finalOutputSize.y <= 0)
-                        error("Video can only be recorded if outputSize is fixed (e.g., video, webcam, IP camera),"
-                              " but not for a image directory.", __LINE__, __FUNCTION__, __FILE__);
                     const auto videoSaver = std::make_shared<VideoSaver>(
-                        wrapperStructOutput.writeVideo, CV_FOURCC('M','J','P','G'), originalVideoFps, finalOutputSize
-                    );
+                        wrapperStructOutput.writeVideo, CV_FOURCC('M','J','P','G'), originalVideoFps);
                     outputWs.emplace_back(std::make_shared<WVideoSaver<TDatumsSP>>(videoSaver));
                 }
                 // Write joint angles as *.bvh file on hard disk

src/openpose/filestream/videoSaver.cpp

@@ -3,11 +3,26 @@
 namespace op
 {
     cv::VideoWriter openVideo(const std::string& videoSaverPath, const int cvFourcc, const double fps,
-                              const Point<int>& cvSize, const int numberImages)
+                              const Point<int>& cvSize)
     {
         try
         {
-            return cv::VideoWriter{videoSaverPath, cvFourcc, fps, cv::Size{numberImages*cvSize.x, cvSize.y}};
+            // Open video
+            const cv::VideoWriter videoWriter{
+                videoSaverPath, cvFourcc, fps, cv::Size{cvSize.x, cvSize.y}};
+            // Check it was successfully opened
+            if (!videoWriter.isOpened())
+            {
+                const std::string errorMessage{
+                    "Video to write frames could not be opened as `" + videoSaverPath + "`. Please, check that:"
+                    "\n\t1. The path ends in `.avi`.\n\t2. The parent folder exists.\n\t3. OpenCV is properly"
+                    " compiled with the FFmpeg codecs in order to save video."
+                    "\n\t4. You are not saving in a protected folder. If you desire to save a video in a"
+                    " protected folder, use sudo (Ubuntu) or execute the binary file as administrator (Windows)."};
+                error(errorMessage, __LINE__, __FUNCTION__, __FILE__);
+            }
+            // Return video
+            return videoWriter;
         }
         catch (const std::exception& e)
         {
@@ -16,32 +31,17 @@ namespace op
         }
     }
 
-    VideoSaver::VideoSaver(const std::string& videoSaverPath, const int cvFourcc, const double fps,
-                           const Point<int>& cvSize) :
+    VideoSaver::VideoSaver(const std::string& videoSaverPath, const int cvFourcc, const double fps) :
         mVideoSaverPath{videoSaverPath},
         mCvFourcc{cvFourcc},
         mFps{fps},
-        mCvSize{cvSize},
-        mNumberImages{1}
+        mVideoStarted{false}
     {
         try
         {
-            // Sanity checks
-            if (cvSize.x <= 0 || cvSize.y <= 0)
-                error("Desired frame size to save the video is <= 0.", __LINE__, __FUNCTION__, __FILE__);
+            // Sanity check
             if (fps <= 0.)
                 error("Desired fps (frame rate) to save the video is <= 0.", __LINE__, __FUNCTION__, __FILE__);
-            // Open video-writter
-            mVideoWriter = openVideo(mVideoSaverPath, mCvFourcc, mFps, mCvSize, mNumberImages);
-            // Check it was successfully opened
-            if (!mVideoWriter.isOpened())
-            {
-                const std::string errorMessage{"Video to write frames could not be opened as `" + videoSaverPath
-                                               + "`. Please, check that:\n\t1. The path ends in `.avi`."
-                                               "\n\t2. The parent folder exists.\n\t3. OpenCV is properly"
-                                               " compiled with the FFmpeg codecs in order to save video."};
-                error(errorMessage, __LINE__, __FUNCTION__, __FILE__);
-            }
         }
         catch (const std::exception& e)
         {
@@ -82,23 +82,33 @@ namespace op
     {
         try
         {
-            // Sanity checks
-            if (!isOpened())
-                error("Video to write frames is not opened.", __LINE__, __FUNCTION__, __FILE__);
+            // Sanity check
             if (cvMats.empty())
                 error("The image(s) to be saved cannot be empty.", __LINE__, __FUNCTION__, __FILE__);
-            // Re-shape video writer if required
-            if (mNumberImages != cvMats.size())
+            // Open video (1st frame)
+            // Done here and not in the constructor to handle cases where the resolution is not known (e.g.,
+            // reading images or multiple cameras)
+            if (!mVideoStarted)
             {
-                mNumberImages = (unsigned int)cvMats.size();
-                mVideoWriter = openVideo(mVideoSaverPath, mCvFourcc, mFps, mCvSize, mNumberImages);
+                mVideoStarted = true;
+                const auto cvSize = cvMats.at(0).size();
+                mCvSize = Point<int>{(int)cvMats.size()*cvSize.width, cvSize.height};
+                mVideoWriter = openVideo(mVideoSaverPath, mCvFourcc, mFps, mCvSize);
             }
+            // Sanity check
+            if (!isOpened())
+                error("Video to write frames is not opened.", __LINE__, __FUNCTION__, __FILE__);
             // Concat images
             cv::Mat cvOutputData;
             if (cvMats.size() > 1)
                 cv::hconcat(cvMats.data(), cvMats.size(), cvOutputData);
             else
                 cvOutputData = cvMats.at(0);
+            // Sanity check
+            if (mCvSize.x != cvOutputData.cols || mCvSize.y != cvOutputData.rows)
+                error("You selected to write video (`--write_video`), but the frames to be saved have different"
+                      " resolution. You can only save frames with the same resolution.",
+                      __LINE__, __FUNCTION__, __FILE__);
             // Save concatenated image
             mVideoWriter.write(cvOutputData);
         }