Handle row_count decrease

Author: ewong-harmonicinc

docs/CHANGES.TXT

@@ -41,6 +41,7 @@
 - Fix: Resolve compile-time error about implicit declarations (#1646)
 - Fix: fatal out of memory error extracting from a VOB PS
 - Fix: Unit Test Rust failing due to changes in Rust Version 1.86.0
+- Fix: handle row_count decrease in CEA-708 C decoder
 
 0.94 (2021-12-14)
 -----------------

src/lib_ccx/ccx_decoders_708.c

@@ -1046,6 +1046,18 @@ void dtvcc_handle_DFx_DefineWindow(dtvcc_service_decoder *decoder, int window_id
 	if (anchor_horizontal > CCX_DTVCC_SCREENGRID_COLUMNS - col_count)
 		anchor_horizontal = CCX_DTVCC_SCREENGRID_COLUMNS - col_count;
 
+	if (window->is_defined) 
+	{
+		if (row_count < window->row_count) 
+		{
+			// Remove the oldest row if the row count is reduced
+			for(int i=row_count; i<window->row_count; i++)
+			{
+				dtvcc_window_rollup(decoder, window);
+			}
+		}
+	}
+
 	window->priority = priority;
 	window->col_lock = col_lock;
 	window->row_lock = row_lock;