1 files changed, 18 insertions, 2 deletions

diff --git a/ui/vnc.c b/ui/vnc.c
index 7b37e3b01f..166d1b5b5f 100644
--- a/ui/vnc.c
+++ b/ui/vnc.c
@@ -840,6 +840,8 @@ int vnc_raw_send_framebuffer_update(VncState *vs, int x, int y, int w, int h)
 int vnc_send_framebuffer_update(VncState *vs, int x, int y, int w, int h)
 {
     int n = 0;
+    bool encode_raw = false;
+    size_t saved_offs = vs->output.offset;
 
     switch(vs->vnc_encoding) {
         case VNC_ENCODING_ZLIB:
@@ -862,10 +864,24 @@ int vnc_send_framebuffer_update(VncState *vs, int x, int y, int w, int h)
             n = vnc_zywrle_send_framebuffer_update(vs, x, y, w, h);
             break;
         default:
-            vnc_framebuffer_update(vs, x, y, w, h, VNC_ENCODING_RAW);
-            n = vnc_raw_send_framebuffer_update(vs, x, y, w, h);
+            encode_raw = true;
             break;
     }
+
+    /* If the client has the same pixel format as our internal buffer and
+     * a RAW encoding would need less space fall back to RAW encoding to
+     * save bandwidth and processing power in the client. */
+    if (!encode_raw && vs->write_pixels == vnc_write_pixels_copy &&
+        12 + h * w * VNC_SERVER_FB_BYTES <= (vs->output.offset - saved_offs)) {
+        vs->output.offset = saved_offs;
+        encode_raw = true;
+    }
+
+    if (encode_raw) {
+        vnc_framebuffer_update(vs, x, y, w, h, VNC_ENCODING_RAW);
+        n = vnc_raw_send_framebuffer_update(vs, x, y, w, h);
+    }
+
     return n;
 }