video encoding

- user has to request ffmpeg support
- handle old version of ffmpeg

CMakeLists.txt

@@ -80,6 +80,8 @@ option(Easy3D_BUILD_TESTS "Build Easy3D Tests"                  OFF)
 option(Easy3D_ENABLE_CGAL "Build advanced features that require CGAL (>= v5.1)"             OFF)
 # Build advanced examples/applications that require Qt5 (>= v5.6)
 option(Easy3D_ENABLE_QT "Build advanced examples/applications that require Qt5 (>= v5.6)"   OFF)
+# Build the video encoding module that requires ffmpeg
+option(Easy3D_ENABLE_FFMPEG "Build the video encoding module that requires ffmpeg"          OFF)
 
 ################################################################################
 
@@ -158,16 +160,29 @@ if (Easy3D_ENABLE_CGAL)
     endif ()
 endif ()
 
-include(./cmake/FindFFMPEG.cmake)
-if (FFMPEG_FOUND)
-    set(Easy3D_HAS_FFMPEG TRUE)
-else ()
-    set(Easy3D_HAS_FFMPEG FALSE)
-    message(WARNING "You have requested FFMPEG support but FFMPEG was not found. "
-            "To use FFMPEG, make sure FFMPEG exists on your system (install/build FFMPEG if necessary). "
-            "You can modify the search paths of 'include' and 'lib' in 'Easy3D/cmake/FindFFMPEG.cmake', "
-            "and then run CMake. The FFMPEG support allows recording animation into a video file. "
-            "Ignore this message if you don't need this feature.")
+if (Easy3D_ENABLE_FFMPEG)
+    include(./cmake/FindFFMPEG.cmake)
+    if (FFMPEG_FOUND)
+        set(Easy3D_HAS_FFMPEG TRUE)
+    else ()
+        set(Easy3D_HAS_FFMPEG FALSE)
+        message(WARNING "You have requested ffmpeg support but ffmpeg was not found (v4.0 or later required). "
+                "The ffmpeg support allows encoding/recording animation into a video file. You can ignore "
+                "this warning if you don't need this feature. \n"
+                "To enable video encoding, make sure ffmpeg exists on your system. Modify the search paths of "
+                "'include' and 'lib' in 'Easy3D/cmake/FindFFMPEG.cmake', and then run CMake. \n"
+                "How to install ffmpeg (v4.0 or later required)? \n"
+                "    On Windows, you can download ffmpeg from:  \n"
+                "       https://ffmpeg.org/download.html \n"
+                "    On macOS, use the following command to install ffmpeg: \n"
+                "       brew install ffmpeg \n"
+                "    On Linux, one has to install the libraries using: \n"
+                "       sudo apt-get install libavcodec-dev \n"
+                "       sudo apt-get install libavformat-dev \n"
+                "       sudo apt-get install libswscale-dev \n"
+                "       sudo apt-get install libavutil-dev \n"
+                )
+    endif ()
 endif ()
 
 ################################################################################
@@ -313,6 +328,7 @@ message(STATUS "    Build documentation    :  ${Easy3D_BUILD_DOCUMENTATION}")
 message(STATUS "    Build tests            :  ${Easy3D_BUILD_TESTS}")
 message(STATUS "    With CGAL (>= v5.1)    :  ${Easy3D_ENABLE_CGAL}")
 message(STATUS "    With Qt5 (>= v5.6)     :  ${Easy3D_ENABLE_QT}")
+message(STATUS "    With ffmpeg (>= v4.0)  :  ${Easy3D_ENABLE_FFMPEG}")
 message(STATUS "    Installation directory :  ${CMAKE_INSTALL_PREFIX}")
 
 message(STATUS "************************************************************")

applications/Mapple/main.cpp

@@ -62,10 +62,13 @@ class Mapple : public QApplication
         try {
             return QApplication::notify(receiver, event);
         } catch(QException& e) {
-            LOG(ERROR) << "an exception was thrown: " << e.what();
+            LOG(ERROR) << "caught an exception: " << e.what();
+        }
+        catch(std::exception& e) {
+            LOG(ERROR) << "caught an exception: " << e.what();
         }
         catch(...) {
-            LOG(ERROR) << "an unknown exception was thrown";
+            LOG(ERROR) << "caught an unknown exception";
         }
         return false;
     }

applications/Mapple/paint_canvas_snapshot.cpp

@@ -262,7 +262,10 @@ void PaintCanvas::recordAnimation(const QString &file_name, int fps, int bit_rat
     const int fh = h * dpi_scaling();
     VideoEncoder encoder;
     if (!encoder.start(file_name.toStdString(), fps, bitrate)) {
+        // clean up and restore the settings before exit
+        encoder.end();
         setEnabled(true);
+        easy3d::connect(&camera_->frame_modified, this, static_cast<void (PaintCanvas::*)(void)>(&PaintCanvas::update));
         return;
     }
 

easy3d/video/CMakeLists.txt

@@ -12,5 +12,5 @@ set(${module}_sources
 
 add_module(${module} "${${module}_headers}" "${${module}_sources}" "${private_dependencies}" "${public_dependencies}")
 target_include_directories(easy3d_${module} PRIVATE ${FFMPEG_INCLUDE_DIRS})
-target_compile_definitions(easy3d_${module} PUBLIC HAS_CGAL)
+target_compile_definitions(easy3d_${module} PUBLIC HAS_FFMPEG)
 install_module(${module})

easy3d/video/video_encoder.cpp

@@ -24,7 +24,7 @@
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  ********************************************************************/
 
-#include "video_encoder.h"
+#include <easy3d/video/video_encoder.h>
 
 extern "C" {
 #include <libavcodec/avcodec.h>
@@ -35,6 +35,13 @@ extern "C" {
 
 #include <easy3d/util/logging.h>
 
+
+// check avcodec version
+#if (LIBAVCODEC_VERSION_INT < AV_VERSION_INT(58, 18, 100)) // this number corresponds to ffmpeg v4.0
+    #pragma message "[WARNING]: Your ffmpeg is too old. Please update it to v4.0 or above"
+#endif
+
+
 namespace internal {
 
 	// a wrapper around a single output AVStream
@@ -287,8 +294,10 @@ namespace internal {
             LOG(WARNING) << "could not deduce output format from file extension: using MPEG";
 			avformat_alloc_output_context2(&fmt_ctx, nullptr, "mpeg", filename_.c_str());
 		}
-		if (!fmt_ctx)
-			return false;
+		if (!fmt_ctx) {
+            LOG(ERROR) << "failed to allocate the output media context";
+            return false;
+        }
 
 		fmt = fmt_ctx->oformat;
 		return true;
@@ -373,6 +382,9 @@ namespace internal {
 
 
 	void VideoEncoderImpl::end() {
+        if (!fmt_ctx) // video context was not created or has already been deleted
+            return;
+
 		av_write_trailer(fmt_ctx);
 
 		/* Close each codec. */
@@ -384,6 +396,7 @@ namespace internal {
 
 		/* free the stream */
 		avformat_free_context(fmt_ctx);
+        fmt_ctx = nullptr;
 	}
 
 }
@@ -394,6 +407,13 @@ using namespace internal;
 namespace easy3d {
 
 	VideoEncoder::VideoEncoder() : encoder_(nullptr) {
+        LOG(INFO) << "ffmpeg version : " << av_version_info();
+        LOG(INFO) << "avcodec_version: "
+            << AV_VERSION_MAJOR(LIBAVCODEC_VERSION_INT) << "."
+            << AV_VERSION_MINOR(LIBAVCODEC_VERSION_INT);
+        if (LIBAVCODEC_VERSION_INT < AV_VERSION_INT(58, 18, 100)) // this number corresponds to ffmpeg v4.0
+            LOG(WARNING) << "your program was built with too old ffmpeg (" << av_version_info() << "), and "
+                         << "video encoding is not available. Contact the author of the program to fix it";
 #ifdef NDEBUG
 		av_log_set_level(AV_LOG_QUIET);
 #else