avutil/pixdesc: Add av_chroma_location_(enum_to_pos|pos_to_enum)

They are intended as replacements for avcodec_enum_to_chroma_pos()
and avcodec_chroma_pos_to_enum().

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

doc/APIchanges

@@ -14,6 +14,9 @@ libavutil:     2021-04-27
 
 API changes, most recent first:
 
+2022-09-26 - xxxxxxxxxx - lavu 57.37.100 - pixdesc.h
+  Add av_chroma_location_enum_to_pos() and av_chroma_location_pos_to_enum().
+
 2022-09-26 - xxxxxxxxxx - lavc 59.47.100 - avcodec.h defs.h
   Move the AV_EF_* and FF_COMPLIANCE_* defines from avcodec.h to defs.h.
 

libavutil/pixdesc.c

@@ -3315,3 +3315,26 @@ int av_chroma_location_from_name(const char *name)
 
     return AVERROR(EINVAL);
 }
+
+int av_chroma_location_enum_to_pos(int *xpos, int *ypos, enum AVChromaLocation pos)
+{
+    if (pos <= AVCHROMA_LOC_UNSPECIFIED || pos >= AVCHROMA_LOC_NB)
+        return AVERROR(EINVAL);
+    pos--;
+
+    *xpos = (pos&1) * 128;
+    *ypos = ((pos>>1)^(pos<4)) * 128;
+
+    return 0;
+}
+
+enum AVChromaLocation av_chroma_location_pos_to_enum(int xpos, int ypos)
+{
+    int pos, xout, yout;
+
+    for (pos = AVCHROMA_LOC_UNSPECIFIED + 1; pos < AVCHROMA_LOC_NB; pos++) {
+        if (av_chroma_location_enum_to_pos(&xout, &yout, pos) == 0 && xout == xpos && yout == ypos)
+            return pos;
+    }
+    return AVCHROMA_LOC_UNSPECIFIED;
+}

libavutil/pixdesc.h

@@ -264,6 +264,28 @@ const char *av_chroma_location_name(enum AVChromaLocation location);
  */
 int av_chroma_location_from_name(const char *name);
 
+/**
+ * Converts AVChromaLocation to swscale x/y chroma position.
+ *
+ * The positions represent the chroma (0,0) position in a coordinates system
+ * with luma (0,0) representing the origin and luma(1,1) representing 256,256
+ *
+ * @param xpos  horizontal chroma sample position
+ * @param ypos  vertical   chroma sample position
+ */
+int av_chroma_location_enum_to_pos(int *xpos, int *ypos, enum AVChromaLocation pos);
+
+/**
+ * Converts swscale x/y chroma position to AVChromaLocation.
+ *
+ * The positions represent the chroma (0,0) position in a coordinates system
+ * with luma (0,0) representing the origin and luma(1,1) representing 256,256
+ *
+ * @param xpos  horizontal chroma sample position
+ * @param ypos  vertical   chroma sample position
+ */
+enum AVChromaLocation av_chroma_location_pos_to_enum(int xpos, int ypos);
+
 /**
  * Return the pixel format corresponding to name.
  *

libavutil/version.h

@@ -79,8 +79,8 @@
  */
 
 #define LIBAVUTIL_VERSION_MAJOR  57
-#define LIBAVUTIL_VERSION_MINOR  36
+#define LIBAVUTIL_VERSION_MINOR  37
-#define LIBAVUTIL_VERSION_MICRO 102
+#define LIBAVUTIL_VERSION_MICRO 100
 
 #define LIBAVUTIL_VERSION_INT   AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \
                                                LIBAVUTIL_VERSION_MINOR, \