Add av_image_check_sar() and use it to validate SAR

3 files changed, 39 insertions, 1 deletions

diff --git a/libavutil/imgutils.c b/libavutil/imgutils.c
index 813724bea7..fc367d921b 100644
--- a/libavutil/imgutils.c
+++ b/libavutil/imgutils.c
@@ -25,7 +25,9 @@
 #include "imgutils.h"
 #include "internal.h"
 #include "log.h"
+#include "mathematics.h"
 #include "pixdesc.h"
+#include "rational.h"
 
 void av_image_fill_max_pixsteps(int max_pixsteps[4], int max_pixstep_comps[4],
                                 const AVPixFmtDescriptor *pixdesc)
@@ -228,6 +230,27 @@ int av_image_check_size(unsigned int w, unsigned int h, int log_offset, void *lo
     return AVERROR(EINVAL);
 }
 
+int av_image_check_sar(unsigned int w, unsigned int h, AVRational sar)
+{
+    int64_t scaled_dim;
+
+    if (!sar.den)
+        return AVERROR(EINVAL);
+
+    if (!sar.num || sar.num == sar.den)
+        return 0;
+
+    if (sar.num < sar.den)
+        scaled_dim = av_rescale_rnd(w, sar.num, sar.den, AV_ROUND_ZERO);
+    else
+        scaled_dim = av_rescale_rnd(h, sar.den, sar.num, AV_ROUND_ZERO);
+
+    if (scaled_dim > 0)
+        return 0;
+
+    return AVERROR(EINVAL);
+}
+
 void av_image_copy_plane(uint8_t       *dst, int dst_linesize,
                          const uint8_t *src, int src_linesize,
                          int bytewidth, int height)
diff --git a/libavutil/imgutils.h b/libavutil/imgutils.h
index 71510132ae..313037ae76 100644
--- a/libavutil/imgutils.h
+++ b/libavutil/imgutils.h
@@ -29,6 +29,7 @@
 
 #include "avutil.h"
 #include "pixdesc.h"
+#include "rational.h"
 
 /**
  * Compute the max pixel step for each plane of an image with a
@@ -128,6 +129,20 @@ void av_image_copy(uint8_t *dst_data[4], int dst_linesizes[4],
  */
 int av_image_check_size(unsigned int w, unsigned int h, int log_offset, void *log_ctx);
 
+/**
+ * Check if the given sample aspect ratio of an image is valid.
+ *
+ * It is considered invalid if the denominator is 0 or if applying the ratio
+ * to the image size would make the smaller dimension less than 1. If the
+ * sar numerator is 0, it is considered unknown and will return as valid.
+ *
+ * @param w width of the image
+ * @param h height of the image
+ * @param sar sample aspect ratio of the image
+ * @return 0 if valid, a negative AVERROR code otherwise
+ */
+int av_image_check_sar(unsigned int w, unsigned int h, AVRational sar);
+
 int avpriv_set_systematic_pal2(uint32_t pal[256], enum AVPixelFormat pix_fmt);
 
 /**
diff --git a/libavutil/version.h b/libavutil/version.h
index 427409f875..a4384b3ea6 100644
--- a/libavutil/version.h
+++ b/libavutil/version.h
@@ -54,7 +54,7 @@
  */
 
 #define LIBAVUTIL_VERSION_MAJOR 53
-#define LIBAVUTIL_VERSION_MINOR 16
+#define LIBAVUTIL_VERSION_MINOR 17
 #define LIBAVUTIL_VERSION_MICRO  0
 
 #define LIBAVUTIL_VERSION_INT   AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \