Added video_format_ScaleCropAr().

It computes correct crop/ar settings when scaling a video format.

include/vlc_es.h

@@ -177,6 +177,11 @@ VLC_EXPORT( void, video_format_Setup, ( video_format_t *, vlc_fourcc_t i_chroma,
  */
 VLC_EXPORT( void, video_format_CopyCrop, ( video_format_t *, const video_format_t * ) );
 
+/**
+ * It will compute the crop/ar properties when scaling.
+ */
+VLC_EXPORT( void, video_format_ScaleCropAr, ( video_format_t *, const video_format_t * ) );
+
 /**
  * This function will check if the first video format is similar
  * to the second one.

src/libvlccore.sym

@@ -486,6 +486,7 @@ var_Type
 var_Inherit
 var_InheritURational
 video_format_CopyCrop
+video_format_ScaleCropAr
 video_format_FixRgb
 video_format_IsSimilar
 video_format_Setup

src/misc/es_format.c

@@ -215,6 +215,24 @@ void video_format_CopyCrop( video_format_t *p_dst, const video_format_t *p_src )
     p_dst->i_visible_height = p_src->i_visible_height;
 }
 
+void video_format_ScaleCropAr( video_format_t *p_dst, const video_format_t *p_src )
+{
+    p_dst->i_x_offset       = (uint64_t)p_src->i_x_offset       * p_dst->i_width  / p_src->i_width;
+    p_dst->i_y_offset       = (uint64_t)p_src->i_y_offset       * p_dst->i_height / p_src->i_height;
+    p_dst->i_visible_width  = (uint64_t)p_src->i_visible_width  * p_dst->i_width  / p_src->i_width;
+    p_dst->i_visible_height = (uint64_t)p_src->i_visible_height * p_dst->i_height / p_src->i_height;
+
+    p_dst->i_sar_num *= p_src->i_width;
+    p_dst->i_sar_den *= p_dst->i_width;
+    vlc_ureduce(&p_dst->i_sar_num, &p_dst->i_sar_den,
+                p_dst->i_sar_num, p_dst->i_sar_den, 65536);
+
+    p_dst->i_sar_num *= p_dst->i_height;
+    p_dst->i_sar_den *= p_src->i_height;
+    vlc_ureduce(&p_dst->i_sar_num, &p_dst->i_sar_den,
+                p_dst->i_sar_num, p_dst->i_sar_den, 65536);
+}
+
 bool video_format_IsSimilar( const video_format_t *p_fmt1, const video_format_t *p_fmt2 )
 {
     video_format_t v1 = *p_fmt1;