From cbcae4856c9693952e32d5239eb1f1e8e811473e Mon Sep 17 00:00:00 2001
From: reimar <reimar@b3059339-0415-0410-9bf9-f77b7e298cf2>
Date: Sat, 23 Jan 2010 19:00:09 +0000
Subject: Make the scale filter prefer yuv conversions that do not need chroma
 scaling. Also always try keeping input and output format the same first.

git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@30409 b3059339-0415-0410-9bf9-f77b7e298cf2
---
 libmpcodecs/vf_scale.c | 48 +++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 41 insertions(+), 7 deletions(-)

diff --git a/libmpcodecs/vf_scale.c b/libmpcodecs/vf_scale.c
index 4bc32fc442..ec18aa82fe 100644
--- a/libmpcodecs/vf_scale.c
+++ b/libmpcodecs/vf_scale.c
@@ -94,14 +94,48 @@ static unsigned int outfmt_list[]={
     0
 };
 
-static unsigned int find_best_out(vf_instance_t *vf){
+/**
+ * A list of preferred conversions, in order of preference.
+ * This should be used for conversions that e.g. involve no scaling
+ * or to stop vf_scale from choosing a conversion that has no
+ * fast assembler implementation.
+ */
+static int preferred_conversions[][2] = {
+    {IMGFMT_YUY2, IMGFMT_UYVY},
+    {IMGFMT_YUY2, IMGFMT_422P},
+    {IMGFMT_UYVY, IMGFMT_YUY2},
+    {IMGFMT_UYVY, IMGFMT_422P},
+    {IMGFMT_422P, IMGFMT_YUY2},
+    {IMGFMT_422P, IMGFMT_UYVY},
+    {0, 0}
+};
+
+static unsigned int find_best_out(vf_instance_t *vf, int in_format){
     unsigned int best=0;
-    int i;
+    int i = -1;
+    int j = -1;
+    int format = 0;
 
     // find the best outfmt:
-    for(i=0; outfmt_list[i]; i++){
-        const int format= outfmt_list[i];
-        int ret = vf_next_query_format(vf, format);
+    while (1) {
+        int ret;
+        if (j < 0) {
+            format = in_format;
+            j = 0;
+        } else if (i < 0) {
+            while (preferred_conversions[j][0] &&
+                   preferred_conversions[j][0] != in_format)
+                j++;
+            format = preferred_conversions[j++][1];
+            // switch to standard list
+            if (!format)
+                i = 0;
+        }
+        if (i >= 0)
+            format = outfmt_list[i++];
+        if (!format)
+            break;
+        ret = vf_next_query_format(vf, format);
 
 	mp_msg(MSGT_VFILTER,MSGL_DBG2,"scale: query(%s) -> %d\n",vo_format_name(format),ret&3);
 	if(ret&VFCAP_CSP_SUPPORTED_BY_HW){
@@ -117,7 +151,7 @@ static unsigned int find_best_out(vf_instance_t *vf){
 static int config(struct vf_instance_s* vf,
         int width, int height, int d_width, int d_height,
 	unsigned int flags, unsigned int outfmt){
-    unsigned int best=find_best_out(vf);
+    unsigned int best=find_best_out(vf, outfmt);
     int vo_flags;
     int int_sws_flags=0;
     int round_w=0, round_h=0;
@@ -490,7 +524,7 @@ static int query_format(struct vf_instance_s* vf, unsigned int fmt){
     case IMGFMT_RGB48LE:
     case IMGFMT_RGB48BE:
     {
-	unsigned int best=find_best_out(vf);
+	unsigned int best=find_best_out(vf, fmt);
 	int flags;
 	if(!best) return 0;	 // no matching out-fmt
 	flags=vf_next_query_format(vf,best);
-- 
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