+/**
+ * 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);
+