subpicture: add premultiplied-alpha and global-alpha feature flags.

Add premultiplied-alpha and global-alpha feature flags, along with converters
between VA-API and gstreamer-vaapi definitions. Another round of helpers is
also necessary for GstVideoOverlayComposition API.

gst-libs/gst/vaapi/gstvaapisubpicture.h

@@ -58,6 +58,21 @@ typedef struct _GstVaapiSubpicture              GstVaapiSubpicture;
 typedef struct _GstVaapiSubpicturePrivate       GstVaapiSubpicturePrivate;
 typedef struct _GstVaapiSubpictureClass         GstVaapiSubpictureClass;
 
+/**
+ * GstVaapiSubpictureFlags:
+ * @GST_VAAPI_SUBPICTURE_FLAG_PREMULTIPLIED_ALPHA:
+ *   subpicture has RGB pixels with pre-multiplied alpha
+ * @GST_VAAPI_SUBPICTURE_FLAG_GLOBAL_ALPHA:
+ *   subpicture needs to be blended with some global-alpha value at
+ *   rendering time
+ *
+ * The set of all subpicture rendering flags for #GstVaapiSubpicture.
+ */
+typedef enum {
+    GST_VAAPI_SUBPICTURE_FLAG_PREMULTIPLIED_ALPHA    = (1 << 0),
+    GST_VAAPI_SUBPICTURE_FLAG_GLOBAL_ALPHA           = (1 << 1),
+} GstVaapiSubpictureFlags;
+
 /**
  * GstVaapiSubpicture:
  *

gst-libs/gst/vaapi/gstvaapiutils.c

@@ -24,6 +24,7 @@
 #include "gstvaapicompat.h"
 #include "gstvaapiutils.h"
 #include "gstvaapisurface.h"
+#include "gstvaapisubpicture.h"
 #include <stdio.h>
 #include <stdarg.h>
 
@@ -202,6 +203,50 @@ string_of_VADisplayAttributeType(VADisplayAttribType attribute_type)
     return "<unknown>";
 }
 
+/**
+ * from_GstVaapiSubpictureFlags:
+ * @flags: the #GstVaapiSubpictureFlags
+ *
+ * Converts #GstVaapiSubpictureFlags to flags suitable for
+ * vaAssociateSubpicture().
+ */
+guint
+from_GstVaapiSubpictureFlags(guint flags)
+{
+    guint va_flags = 0;
+
+    if (flags & GST_VAAPI_SUBPICTURE_FLAG_GLOBAL_ALPHA)
+        va_flags |= VA_SUBPICTURE_GLOBAL_ALPHA;
+#ifdef VA_SUBPICTURE_PREMULTIPLIED_ALPHA
+    if (flags & GST_VAAPI_SUBPICTURE_FLAG_PREMULTIPLIED_ALPHA)
+        flags |= VA_SUBPICTURE_PREMULTIPLIED_ALPHA;
+#endif
+    return va_flags;
+}
+
+/**
+ * to_GstVaapiSubpictureFlags:
+ * @flags: the #GstVaapiSubpictureFlags flags to translate
+ *
+ * Converts vaQuerySubpictureFormats() @flags to #GstVaapiSubpictureFlags
+ * flags.
+ *
+ * Return value: the #GstVaapiSubpictureFlags flags
+ */
+guint
+to_GstVaapiSubpictureFlags(guint va_flags)
+{
+    guint flags = 0;
+
+    if (va_flags & VA_SUBPICTURE_GLOBAL_ALPHA)
+        flags |= GST_VAAPI_SUBPICTURE_FLAG_GLOBAL_ALPHA;
+#ifdef VA_SUBPICTURE_PREMULTIPLIED_ALPHA
+    if (va_flags & VA_SUBPICTURE_PREMULTIPLIED_ALPHA)
+        flags |= GST_VAAPI_SUBPICTURE_FLAG_PREMULTIPLIED_ALPHA;
+#endif
+    return flags;
+}
+
 /**
  * from_GstVaapiSurfaceRenderFlags:
  * @flags: the #GstVaapiSurfaceRenderFlags

gst-libs/gst/vaapi/gstvaapiutils.h

@@ -73,6 +73,14 @@ G_GNUC_INTERNAL
 const char *
 string_of_VADisplayAttributeType(VADisplayAttribType attribute_type);
 
+G_GNUC_INTERNAL
+guint
+from_GstVaapiSubpictureFlags(guint flags);
+
+G_GNUC_INTERNAL
+guint
+to_GstVaapiSubpictureFlags(guint va_flags);
+
 G_GNUC_INTERNAL
 guint
 from_GstVaapiSurfaceRenderFlags(guint flags);