[GL] Modify the FFMPeg recorder to be able to use it in SofaGLFW (#5862)

* Add a quiet option for some filesystem methods that only perform tests while keeping old behavior s default for compatibility

* Modify the FFMPeg recorder to be able to use it in SofaGLFW

* Quietly check for file exists

---------

Co-authored-by: Hugo <hugo.talbot@sofa-framework.org>

Author: bakpaul

Sofa/GL/src/sofa/gl/VideoRecorderFFMPEG.cpp

@@ -96,8 +96,9 @@ bool VideoRecorderFFMPEG::init(const std::string& ffmpeg_exec_filepath, const st
         extension = ".exe";
 #endif
         m_ffmpegExecPath = helper::Utils::getExecutablePath() + "/ffmpeg" + extension;
-        if(!FileSystem::isFile(m_ffmpegExecPath))
+        if(!FileSystem::isFile(m_ffmpegExecPath, true))
         {
+            msg_warning("VideoRecorderFFMPEG")<< "ffmpeg hasn't been found automatically. Falling back to simply calling ffmpeg"<< extension <<" and hope that the OS finds it on its own. " ;
             // Fallback to a relative FFMPEG (may be in system or exposed in PATH)
             m_ffmpegExecPath = "ffmpeg" + extension;
         }
@@ -138,31 +139,38 @@ void VideoRecorderFFMPEG::addFrame()
 {        
     GLint viewport[4];
     glGetIntegerv(GL_VIEWPORT, viewport);
-   
+
     if ((viewport[2] != m_viewportWidth) || (viewport[3] != m_viewportHeight))
     {
         std::cout << "WARNING viewport changed during video capture from " << m_viewportWidth << "x" << m_viewportHeight << "  to  " << viewport[2] << "x" << viewport[3] << std::endl;
     }
 
+    glReadPixels(viewport[0], viewport[1], m_viewportWidth, m_viewportHeight, GL_RGBA, GL_UNSIGNED_BYTE, (void*)m_viewportBuffer);
+
+    addFrame(m_viewportBuffer, m_viewportWidth, m_viewportHeight);
+}
+
 
-    glReadPixels(0, 0, m_viewportWidth, m_viewportHeight, GL_RGBA, GL_UNSIGNED_BYTE, (void*)m_viewportBuffer);
 
-    // set ffmpeg buffer: initialize to 0 (black) 
+void VideoRecorderFFMPEG::addFrame(unsigned char* rgbData, int fbWidth, int fbHeight)
+{
+
+    // set ffmpeg buffer: initialize to 0 (black)
     memset(m_ffmpegBuffer, 0, m_ffmpegBufferSize);
 
-    if (m_viewportWidth == m_ffmpegWidth)
+    if (fbWidth == m_ffmpegWidth)
     {
-        memcpy(m_ffmpegBuffer, m_viewportBuffer, m_viewportBufferSize);
+        memcpy(m_ffmpegBuffer, rgbData, fbHeight * fbWidth * m_pixelFormatSize);
     }
     else
     {
-        const unsigned char* viewportBufferIter = m_viewportBuffer;
-        const size_t viewportRowSizeInBytes = m_pixelFormatSize * m_viewportWidth;
+        const unsigned char* viewportBufferIter = rgbData;
+        const size_t viewportRowSizeInBytes = m_pixelFormatSize * fbWidth;
 
         unsigned char* ffmpegBufferIter = m_ffmpegBuffer;
         const size_t ffmpegRowSizeInBytes = m_pixelFormatSize * m_ffmpegWidth;
 
-        int row = m_viewportHeight;
+        int row = fbHeight;
         while ( row-- > 0 )
         {
             memcpy( ffmpegBufferIter, viewportBufferIter, viewportRowSizeInBytes);
@@ -174,8 +182,6 @@ void VideoRecorderFFMPEG::addFrame()
 
 
     fwrite(m_ffmpegBuffer, m_ffmpegBufferSize, 1, m_ffmpeg);
-    
-    return;
 }
 
 void VideoRecorderFFMPEG::finishVideo()

Sofa/GL/src/sofa/gl/VideoRecorderFFMPEG.h

@@ -62,9 +62,14 @@ class SOFA_GL_API VideoRecorderFFMPEG
     bool init(const std::string& ffmpeg_exec_filepath, const std::string& filename, int width, int height, unsigned int framerate, unsigned int bitrate, const std::string& codec="");
 
     void addFrame();
+    void addFrame(unsigned char* rgbData, int fbWidth, int fbHeight);
     void saveVideo();
     void finishVideo();
 
+    int getPixelFormatSize()
+    {
+        return m_pixelFormatSize;
+    };
 
     void setPrefix(const std::string v) { m_prefix = v; }