Check for input/output size match here too. I hope that I didn't forget other files.

modules/video_chroma/grey_yuv.c

@@ -72,6 +72,10 @@ static int Activate( vlc_object_t *p_this )
         return -1;
     }
 
+    if( p_filter->fmt_in.video.i_width != p_filter->fmt_out.video.i_width
+     || p_filter->fmt_in.video.i_height != p_filter->fmt_out.video.i_height )
+        return -1;
+
     switch( p_filter->fmt_in.video.i_chroma )
     {
         case VLC_FOURCC('Y','8','0','0'):

modules/video_chroma/i420_ymga.c

@@ -76,6 +76,10 @@ static int Activate( vlc_object_t *p_this )
         return -1;
     }
 
+    if( p_filter->fmt_in.video.i_width != p_filter->fmt_out.video.i_width
+     || p_filter->fmt_in.video.i_height != p_filter->fmt_out.video.i_height )
+        return -1;
+
     switch( p_filter->fmt_in.video.i_chroma )
     {
         case VLC_FOURCC('Y','V','1','2'):

modules/video_chroma/i422_i420.c

@@ -74,6 +74,10 @@ static int Activate( vlc_object_t *p_this )
         return -1;
     }
 
+    if( p_filter->fmt_in.video.i_width != p_filter->fmt_out.video.i_width
+     || p_filter->fmt_in.video.i_height != p_filter->fmt_out.video.i_height )
+        return -1;
+
     switch( p_filter->fmt_in.video.i_chroma )
     {
         case VLC_FOURCC('I','4','2','2'):

modules/video_chroma/yuy2_i422.c

@@ -75,6 +75,10 @@ static int Activate( vlc_object_t *p_this )
         return -1;
     }
 
+    if( p_filter->fmt_in.video.i_width != p_filter->fmt_out.video.i_width
+     || p_filter->fmt_in.video.i_height != p_filter->fmt_out.video.i_height )
+        return -1;
+
     switch( p_filter->fmt_out.video.i_chroma )
     {
         case VLC_FOURCC('I','4','2','2'):