swscale/utils: Detect and skip unneeded sws_setColorspaceDetails() calls

This avoids running various table inits unnecessarily
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libswscale/utils.c

@@ -832,8 +832,6 @@ int sws_setColorspaceDetails(struct SwsContext *c, const int inv_table[4],
     const AVPixFmtDescriptor *desc_dst;
     const AVPixFmtDescriptor *desc_src;
     int need_reinit = 0;
-    memmove(c->srcColorspaceTable, inv_table, sizeof(int) * 4);
-    memmove(c->dstColorspaceTable, table, sizeof(int) * 4);
 
     handle_formats(c);
     desc_dst = av_pix_fmt_desc_get(c->dstFormat);
@@ -844,11 +842,24 @@ int sws_setColorspaceDetails(struct SwsContext *c, const int inv_table[4],
     if(!isYUV(c->srcFormat) && !isGray(c->srcFormat))
         srcRange = 0;
 
+    if (c->srcRange != srcRange ||
+        c->dstRange != dstRange ||
+        c->brightness != brightness ||
+        c->contrast   != contrast ||
+        c->saturation != saturation ||
+        memcmp(c->srcColorspaceTable, inv_table, sizeof(int) * 4) ||
+        memcmp(c->dstColorspaceTable,     table, sizeof(int) * 4)
+    )
+        need_reinit = 1;
+
+    memmove(c->srcColorspaceTable, inv_table, sizeof(int) * 4);
+    memmove(c->dstColorspaceTable, table, sizeof(int) * 4);
+
+
+
     c->brightness = brightness;
     c->contrast   = contrast;
     c->saturation = saturation;
-    if (c->srcRange != srcRange || c->dstRange != dstRange)
-        need_reinit = 1;
     c->srcRange   = srcRange;
     c->dstRange   = dstRange;
 
@@ -863,6 +874,9 @@ int sws_setColorspaceDetails(struct SwsContext *c, const int inv_table[4],
     if (c->cascaded_context[c->cascaded_mainindex])
         return sws_setColorspaceDetails(c->cascaded_context[c->cascaded_mainindex],inv_table, srcRange,table, dstRange, brightness,  contrast, saturation);
 
+    if (!need_reinit)
+        return 0;
+
     if ((isYUV(c->dstFormat) || isGray(c->dstFormat)) && (isYUV(c->srcFormat) || isGray(c->srcFormat))) {
         if (!c->cascaded_context[0] &&
             memcmp(c->dstColorspaceTable, c->srcColorspaceTable, sizeof(int) * 4) &&