spherical: Add tiled equirectangular type and projection-specific properties

Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>

3 files changed, 94 insertions, 2 deletions

diff --git a/libavutil/spherical.c b/libavutil/spherical.c
index 816452cbd6..0ca2dd367a 100644
--- a/libavutil/spherical.c
+++ b/libavutil/spherical.c
@@ -32,3 +32,21 @@ AVSphericalMapping *av_spherical_alloc(size_t *size)
 
     return spherical;
 }
+
+void av_spherical_tile_bounds(AVSphericalMapping *map,
+                              size_t width, size_t height,
+                              size_t *left, size_t *top,
+                              size_t *right, size_t *bottom)
+{
+    /* conversion from 0.32 coordinates to pixels */
+    uint64_t orig_width  = (uint64_t) width  * UINT32_MAX /
+                           (UINT32_MAX - map->bound_right  - map->bound_left);
+    uint64_t orig_height = (uint64_t) height * UINT32_MAX /
+                           (UINT32_MAX - map->bound_bottom - map->bound_top);
+
+    /* add a (UINT32_MAX - 1) to round up integer division */
+    *left   = (orig_width  * map->bound_left + UINT32_MAX - 1) / UINT32_MAX;
+    *top    = (orig_height * map->bound_top  + UINT32_MAX - 1) / UINT32_MAX;
+    *right  = orig_width  - width  - *left;
+    *bottom = orig_height - height - *top;
+}
diff --git a/libavutil/spherical.h b/libavutil/spherical.h
index eeda625231..db9bdc0be5 100644
--- a/libavutil/spherical.h
+++ b/libavutil/spherical.h
@@ -63,6 +63,13 @@ enum AVSphericalProjection {
      * to the back.
      */
     AV_SPHERICAL_CUBEMAP,
+
+    /**
+     * Video represents a portion of a sphere mapped on a flat surface
+     * using equirectangular projection. The @ref bounding fields indicate
+     * the position of the current video in a larger surface.
+     */
+    AV_SPHERICAL_EQUIRECTANGULAR_TILE,
 };
 
 /**
@@ -122,6 +129,57 @@ typedef struct AVSphericalMapping {
     /**
      * @}
      */
+
+    /**
+     * @name Bounding rectangle
+     * @anchor bounding
+     * @{
+     * These fields indicate the location of the current tile, and where
+     * it should be mapped relative to the original surface. They are
+     * exported as 0.32 fixed point, and can be converted to classic
+     * pixel values with av_spherical_bounds().
+     *
+     * @code{.unparsed}
+     *      +----------------+----------+
+     *      |                |bound_top |
+     *      |            +--------+     |
+     *      | bound_left |tile    |     |
+     *      +<---------->|        |<--->+bound_right
+     *      |            +--------+     |
+     *      |                |          |
+     *      |    bound_bottom|          |
+     *      +----------------+----------+
+     * @endcode
+     *
+     * If needed, the original video surface dimensions can be derived
+     * by adding the current stream or frame size to the related bounds,
+     * like in the following example:
+     *
+     * @code{c}
+     *     original_width  = tile->width  + bound_left + bound_right;
+     *     original_height = tile->height + bound_top  + bound_bottom;
+     * @endcode
+     *
+     * @note These values are valid only for the tiled equirectangular
+     *       projection type (@ref AV_SPHERICAL_EQUIRECTANGULAR_TILE),
+     *       and should be ignored in all other cases.
+     */
+    size_t bound_left;   ///< Distance from the left edge
+    size_t bound_top;    ///< Distance from the top edge
+    size_t bound_right;  ///< Distance from the right edge
+    size_t bound_bottom; ///< Distance from the bottom edge
+    /**
+     * @}
+     */
+
+    /**
+     * Number of pixels to pad from the edge of each cube face.
+     *
+     * @note This value is valid for only for the cubemap projection type
+     *       (@ref AV_SPHERICAL_CUBEMAP), and should be ignored in all other
+     *       cases.
+     */
+    size_t padding;
 } AVSphericalMapping;
 
 /**
@@ -133,6 +191,22 @@ typedef struct AVSphericalMapping {
 AVSphericalMapping *av_spherical_alloc(size_t *size);
 
 /**
+ * Convert the @ref bounding fields from an AVSphericalVideo
+ * from 0.32 fixed point to pixels.
+ *
+ * @param map    The AVSphericalVideo map to read bound values from.
+ * @param width  Width of the current frame or stream.
+ * @param height Height of the current frame or stream.
+ * @param left   Pixels from the left edge.
+ * @param top    Pixels from the top edge.
+ * @param right  Pixels from the right edge.
+ * @param bottom Pixels from the bottom edge.
+ */
+void av_spherical_tile_bounds(AVSphericalMapping *map,
+                              size_t width, size_t height,
+                              size_t *left, size_t *top,
+                              size_t *right, size_t *bottom);
+/**
  * @}
  * @}
  */
diff --git a/libavutil/version.h b/libavutil/version.h
index 3cf9d7ff15..4d5a405130 100644
--- a/libavutil/version.h
+++ b/libavutil/version.h
@@ -79,8 +79,8 @@
  */
 
 #define LIBAVUTIL_VERSION_MAJOR  55
-#define LIBAVUTIL_VERSION_MINOR  47
-#define LIBAVUTIL_VERSION_MICRO 101
+#define LIBAVUTIL_VERSION_MINOR  48
+#define LIBAVUTIL_VERSION_MICRO 100
 
 #define LIBAVUTIL_VERSION_INT   AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \
                                                LIBAVUTIL_VERSION_MINOR, \