swscale: add sws_is_noop()

Exactly what it says on the tin.

Sponsored-by: Sovereign Tech Fund
Signed-off-by: Niklas Haas <git@haasn.dev>

1 files changed, 14 insertions, 0 deletions

diff --git a/libswscale/utils.c b/libswscale/utils.c
index c9c80fdb79..3008d4db4d 100644
--- a/libswscale/utils.c
+++ b/libswscale/utils.c
@@ -2777,3 +2777,17 @@ int sws_test_frame(const AVFrame *frame, int output)
 
     return 1;
 }
+
+int sws_is_noop(const AVFrame *dst, const AVFrame *src)
+{
+    for (int field = 0; field < 2; field++) {
+        SwsFormat dst_fmt = ff_fmt_from_frame(dst, field);
+        SwsFormat src_fmt = ff_fmt_from_frame(src, field);
+        if (!ff_fmt_equal(&dst_fmt, &src_fmt))
+            return 0;
+        if (!dst_fmt.interlaced)
+            break;
+    }
+
+    return 1;
+}