Move glClear and glx/eglSwapBuffers from capture backends to main

src/main.cpp

@@ -1731,7 +1731,7 @@ static void list_supported_capture_options(gsr_egl *egl, bool wayland) {
 #endif
 }
 
-static void list_command() {
+static void info_command() {
     bool wayland = false;
     Display *dpy = XOpenDisplay(nullptr);
     if (!dpy) {
@@ -2022,7 +2022,7 @@ int main(int argc, char **argv) {
         usage_full();
 
     if(argc == 2 && strcmp(argv[1], "--info") == 0) {
-        list_command();
+        info_command();
         _exit(0);
     }
 
@@ -3154,7 +3154,10 @@ int main(int argc, char **argv) {
             const int num_frames = framerate_mode == FramerateMode::CONSTANT ? std::max((int64_t)0LL, expected_frames - video_pts_counter) : 1;
 
             if(num_frames > 0 && !paused) {
+                egl.glClear(0);
                 gsr_capture_capture(capture, video_frame, &color_conversion);
+                gsr_egl_swap_buffers(&egl);
+
                 gsr_video_encoder_copy_textures_to_frame(video_encoder, video_frame);
 
                 if(hdr && !hdr_metadata_set && replay_buffer_size_secs == -1 && add_hdr_metadata_to_video_stream(capture, video_stream))