Implementation of Pixel Buffer Object for Media Player.

MediaPlayer.cpp

@@ -57,6 +57,12 @@ MediaPlayer::MediaPlayer(string name) : id_(name)
     current_segment_ = segments_.begin();
     v_frame_.buffer = nullptr;
 
+    // no PBO by default
+    pbo_[0] = pbo_[1] = 0;
+    pbo_size_ = 0;
+    pbo_index_ = 0;
+    pbo_next_index_ = 1;
+
     textureindex_ = 0;
 }
 
@@ -475,6 +481,69 @@ std::list< std::pair<guint64, guint64> > MediaPlayer::getPlaySegments() const
     return ret;
 }
 
+void MediaPlayer::init_texture()
+{
+    glActiveTexture(GL_TEXTURE0);
+    glGenTextures(1, &textureindex_);
+    glBindTexture(GL_TEXTURE_2D, textureindex_);
+    glPixelStorei(GL_UNPACK_ALIGNMENT, 4);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width_, height_,
+                 0, GL_RGBA, GL_UNSIGNED_BYTE, v_frame_.data[0]);
+
+
+    if (!isimage_ && Rendering::supportsPBO()) {
+
+        // need to fill image size
+        pbo_size_ = height_ * width_ * 4;
+
+        // create 2 pixel buffer objects,
+        glGenBuffers(2, pbo_);
+        // create first PBO
+        glBindBuffer(GL_PIXEL_UNPACK_BUFFER, pbo_[0]);
+        // glBufferDataARB with NULL pointer reserves only memory space.
+        glBufferData(GL_PIXEL_UNPACK_BUFFER, pbo_size_, 0, GL_STREAM_DRAW);
+        // fill in with reset picture
+        GLubyte* ptr = (GLubyte*) glMapBuffer(GL_PIXEL_UNPACK_BUFFER, GL_WRITE_ONLY);
+        if (ptr)  {
+            // update data directly on the mapped buffer
+            memmove(ptr, v_frame_.data[0], pbo_size_);
+            // release pointer to mapping buffer
+            glUnmapBuffer(GL_PIXEL_UNPACK_BUFFER);
+        }
+        else {
+            // did not work, disable PBO
+            glDeleteBuffers(2, pbo_);
+            pbo_[0] = pbo_[1] = 0;
+            pbo_size_ = 0;
+        }
+
+        // idem with second PBO
+        glBindBuffer(GL_PIXEL_UNPACK_BUFFER, pbo_[1]);
+        glBufferData(GL_PIXEL_UNPACK_BUFFER, pbo_size_, 0, GL_STREAM_DRAW);
+        ptr = (GLubyte*) glMapBuffer(GL_PIXEL_UNPACK_BUFFER, GL_WRITE_ONLY);
+        if (ptr) {
+            memmove(ptr, v_frame_.data[0], pbo_size_);
+            glUnmapBuffer(GL_PIXEL_UNPACK_BUFFER);
+        }
+        else {
+            // did not work, disable PBO
+            glDeleteBuffers(2, pbo_);
+            pbo_[0] = pbo_[1] = 0;
+            pbo_size_ = 0;
+        }
+
+        // should be good to go, wrap it up
+        glBindBuffer(GL_PIXEL_UNPACK_BUFFER, 0);
+        pbo_index_ = 0;
+        pbo_next_index_ = 1;
+
+        Log::Info("Using PBO");
+    }
+
+}
+
 void MediaPlayer::update()
 {
     // discard 
@@ -495,18 +564,45 @@ void MediaPlayer::update()
     if (v_frame_is_full_) {
         // first occurence; create texture
         if (textureindex_==0) {
-            glActiveTexture(GL_TEXTURE0);
-            glGenTextures(1, &textureindex_);
-            glBindTexture(GL_TEXTURE_2D, textureindex_);
-            glPixelStorei(GL_UNPACK_ALIGNMENT, 4);
-            glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
-            glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
-            glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width_, height_,
-                         0, GL_RGBA, GL_UNSIGNED_BYTE, v_frame_.data[0]);
+            init_texture();
         }
-        else // bind texture
+        // all other times, bind and fill texture
+        else
         {
             glBindTexture(GL_TEXTURE_2D, textureindex_);
+
+            if (pbo_size_ > 0) {
+
+                // bind PBO to read pixels
+                glBindBuffer(GL_PIXEL_UNPACK_BUFFER, pbo_[pbo_index_]);
+
+                // copy pixels from PBO to texture object
+                glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, width_, height_, GL_RGBA, GL_UNSIGNED_BYTE, 0);
+
+                // bind the next PBO to write pixels
+                // NB : equivalent but faster (memmove instead of memcpy ?) than
+                // glNamedBufferSubData(pboIds[nextIndex], 0, imgsize, vp->getBuffer())
+
+                glBindBuffer(GL_PIXEL_UNPACK_BUFFER, pbo_[pbo_next_index_]);
+                glBufferData(GL_PIXEL_UNPACK_BUFFER, pbo_size_, 0, GL_STREAM_DRAW);
+
+                // map the buffer object into client's memory
+                GLubyte* ptr = (GLubyte*) glMapBuffer(GL_PIXEL_UNPACK_BUFFER, GL_WRITE_ONLY);
+                if (ptr) {
+                    // update data directly on the mapped buffer
+                    memmove(ptr, v_frame_.data[0], pbo_size_);
+                    // release pointer to mapping buffer
+                    glUnmapBuffer(GL_PIXEL_UNPACK_BUFFER);
+                }
+
+                glBindBuffer(GL_PIXEL_UNPACK_BUFFER, 0);
+
+                // In dual PBO mode, increment current index first then get the next index
+                pbo_index_ = (pbo_index_ + 1) % 2;
+                pbo_next_index_ = (pbo_index_ + 1) % 2;
+            }
+            else
+                // without PBO, use standard opengl (slower)
                 glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, width_, height_,
                             GL_RGBA, GL_UNSIGNED_BYTE, v_frame_.data[0]);
         }        

MediaPlayer.h

@@ -253,6 +253,11 @@ private:
     std::atomic<bool> v_frame_is_full_;
     std::atomic<bool> need_loop_;
 
+    // for PBO
+    guint pbo_[2];
+    guint pbo_index_, pbo_next_index_;
+    guint pbo_size_;
+
     MediaSegmentSet segments_;
     MediaSegmentSet::iterator current_segment_;
 
@@ -263,6 +268,7 @@ private:
     bool interlaced_;
     bool enabled_;
 
+    void init_texture();
     void execute_open();
     void execute_loop_command();
     void execute_seek_command(GstClockTime target = GST_CLOCK_TIME_NONE);   

RenderingManager.cpp

@@ -691,6 +691,20 @@ void RenderingWindow::draw(FrameBuffer *fb)
     glfwMakeContextCurrent(master_);
 }
 
+
+bool Rendering::supportsPBO()
+{
+    static int support_extension = -1;
+    if (support_extension < 0) {
+        if (GLAD_GL_ARB_pixel_buffer_object || GLAD_GL_EXT_pixel_buffer_object)
+            support_extension = 1;
+        else
+            support_extension = 0;
+    }
+
+    return support_extension == 1;
+}
+
 //
 // Discarded because not working under OSX - kept in case it would become useful
 //

RenderingManager.h

@@ -130,6 +130,7 @@ public:
     // unproject from window coordinate
     glm::vec3 unProject(glm::vec2 screen_coordinate, glm::mat4 modelview = glm::mat4(1.f));
 
+    static bool supportsPBO();
 
 private: