video: add macros checking for GST_VIDEO_BUFFER_FLAG_TOP/BOTTOM_FIELD flags

The GST_VIDEO_BUFFER_FLAG_TOP_FIELD flag is a superset of
GST_VIDEO_BUFFER_FLAG_BOTTOM_FIELD as they are defined using other
flags. As a result we can't use GST_BUFFER_FLAG_IS_SET() to check for
those flags.

gst-libs/gst/video/video-frame.h

@@ -173,9 +173,11 @@ gboolean    gst_video_frame_copy_plane    (GstVideoFrame *dest, const GstVideoFr
  * @GST_VIDEO_BUFFER_FLAG_TOP_FIELD:   The video frame has the top field only. This is the
  *                                     same as GST_VIDEO_BUFFER_FLAG_TFF |
  *                                     GST_VIDEO_BUFFER_FLAG_ONEFIELD (Since: 1.16).
+ *                                     Use GST_VIDEO_BUFFER_IS_TOP_FIELD() to check for this flag.
  * @GST_VIDEO_BUFFER_FLAG_BOTTOM_FIELD: The video frame has the bottom field only. This is
  *                                     the same as GST_VIDEO_BUFFER_FLAG_ONEFIELD
  *                                     (GST_VIDEO_BUFFER_FLAG_TFF flag unset) (Since: 1.16).
+ *                                     Use GST_VIDEO_BUFFER_IS_BOTTOM_FIELD() to check for this flag.
  * @GST_VIDEO_BUFFER_FLAG_MARKER:      The #GstBuffer contains the end of a video field or frame
  *                                     boundary such as the last subframe or packet (Since: 1.18).
  * @GST_VIDEO_BUFFER_FLAG_LAST:        Offset to define more flags
@@ -204,6 +206,26 @@ typedef enum {
   GST_VIDEO_BUFFER_FLAG_LAST        = (GST_BUFFER_FLAG_LAST << 8)
 } GstVideoBufferFlags;
 
+/* GST_VIDEO_BUFFER_FLAG_TOP_FIELD is a subset of
+ * GST_VIDEO_BUFFER_FLAG_BOTTOM_FIELD so needs to be checked accordingly. */
+#define _GST_VIDEO_BUFFER_FLAG_FIELD_MASK GST_VIDEO_BUFFER_FLAG_TOP_FIELD
+
+/**
+ * GST_VIDEO_BUFFER_IS_TOP_FIELD:
+ * @buf: a #GstBuffer
+ *
+ * Check if GST_VIDEO_BUFFER_FLAG_TOP_FIELD is set on @buf (Since: 1.18).
+ */
+#define GST_VIDEO_BUFFER_IS_TOP_FIELD(buf) ((GST_BUFFER_FLAGS (buf) & _GST_VIDEO_BUFFER_FLAG_FIELD_MASK) == GST_VIDEO_BUFFER_FLAG_TOP_FIELD)
+
+/**
+ * GST_VIDEO_BUFFER_IS_BOTTOM_FIELD:
+ * @buf: a #GstBuffer
+ *
+ * Check if GST_VIDEO_BUFFER_FLAG_BOTTOM_FIELD is set on @buf (Since: 1.18).
+ */
+#define GST_VIDEO_BUFFER_IS_BOTTOM_FIELD(buf) ((GST_BUFFER_FLAGS (buf) & _GST_VIDEO_BUFFER_FLAG_FIELD_MASK) == GST_VIDEO_BUFFER_FLAG_BOTTOM_FIELD)
+
 /**
  * GstVideoFrameMapFlags:
  * @GST_VIDEO_FRAME_MAP_FLAG_NO_REF:  Don't take another reference of the buffer and store it in

tests/check/libs/video.c

@@ -3747,6 +3747,30 @@ GST_START_TEST (test_video_meta_align)
 
 GST_END_TEST;
 
+GST_START_TEST (test_video_flags)
+{
+  GstBuffer *buf;
+
+  buf = gst_buffer_new ();
+  fail_unless (!GST_VIDEO_BUFFER_IS_TOP_FIELD (buf));
+  fail_unless (!GST_VIDEO_BUFFER_IS_BOTTOM_FIELD (buf));
+  gst_buffer_unref (buf);
+
+  buf = gst_buffer_new ();
+  GST_BUFFER_FLAG_SET (buf, GST_VIDEO_BUFFER_FLAG_TOP_FIELD);
+  fail_unless (GST_VIDEO_BUFFER_IS_TOP_FIELD (buf));
+  fail_unless (!GST_VIDEO_BUFFER_IS_BOTTOM_FIELD (buf));
+  gst_buffer_unref (buf);
+
+  buf = gst_buffer_new ();
+  GST_BUFFER_FLAG_SET (buf, GST_VIDEO_BUFFER_FLAG_BOTTOM_FIELD);
+  fail_unless (!GST_VIDEO_BUFFER_IS_TOP_FIELD (buf));
+  fail_unless (GST_VIDEO_BUFFER_IS_BOTTOM_FIELD (buf));
+  gst_buffer_unref (buf);
+}
+
+GST_END_TEST;
+
 static Suite *
 video_suite (void)
 {
@@ -3797,6 +3821,7 @@ video_suite (void)
   tcase_add_test (tc_chain, test_video_format_info_plane_to_components);
   tcase_add_test (tc_chain, test_video_info_align);
   tcase_add_test (tc_chain, test_video_meta_align);
+  tcase_add_test (tc_chain, test_video_flags);
 
   return s;
 }