multi-res: disable intra on forced ref frames

If a reference frame is forced because of low dissimilarity, then
shut off the search of intra modes. This change has mixed results. On
one clip (QVGA), it hurt quality by ~1.5% with negligible speed impact.
On another (VGA) it had negligible affect on quality, but a ~0.2% speed
impact.

Change-Id: Ic8b07648979d732f489de5f094957e140f84d2eb

diff --git a/vp8/encoder/pickinter.c b/vp8/encoder/pickinter.c
index 726026e..8ca77b9 100644 (file)
--- a/vp8/encoder/pickinter.c
+++ b/vp8/encoder/pickinter.c
@@ -650,7 +650,7 @@ void vp8_pick_inter_mode(VP8_COMP *cpi, MACROBLOCK *x, int recon_yoffset,
 #if CONFIG_MULTI_RES_ENCODING
     if (parent_ref_valid && parent_ref_frame && dissim < 8)
     {
-        ref_frame_map[0] = INTRA_FRAME;
+        ref_frame_map[0] = -1;
         ref_frame_map[1] = parent_ref_frame;
         ref_frame_map[2] = -1;
         ref_frame_map[3] = -1;