backend and frontend: port frame sending to flatbuffers

schema/video.fbs

@@ -0,0 +1,34 @@
+namespace VideoUpdate;
+
+
+table Setup {
+  video_format: string;
+  width: uint16;
+  height: uint16;
+  redraw_rate: uint16;
+}
+
+enum FrameType: byte {
+  PFRAME,
+  IDR,
+}
+
+table DecodeUnit {
+  frame_number: uint16;
+  frame_type: FrameType;
+
+  receive_time_ms: uint16;
+
+  data: [ubyte]; 
+}
+
+union Update {
+    Setup:Setup,
+    DecodeUnit:DecodeUnit,
+}
+
+table VideoUpdate {
+    update: Update; 
+}
+
+root_type VideoUpdate;