lavu/opt: add flag to return NULL when applicable in av_opt_get

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

1 files changed, 10 insertions, 0 deletions

diff --git a/libavutil/opt.h b/libavutil/opt.h
index ef90e9c87a..753434d628 100644
--- a/libavutil/opt.h
+++ b/libavutil/opt.h
@@ -564,6 +564,12 @@ int av_opt_eval_q     (void *obj, const AVOption *o, const char *val, AVRational
 #define AV_OPT_SEARCH_FAKE_OBJ   (1 << 1)
 
 /**
+ *  In av_opt_get, return NULL if the option has a pointer type and is set to NULL,
+ *  rather than returning an empty string.
+ */
+#define AV_OPT_ALLOW_NULL (1 << 2)
+
+/**
  *  Allows av_opt_query_ranges and av_opt_query_ranges_default to return more than
  *  one component for certain option types.
  *  @see AVOptionRanges for details.
@@ -722,6 +728,10 @@ int av_opt_set_dict_val(void *obj, const char *name, const AVDictionary *val, in
  */
 /**
  * @note the returned string will be av_malloc()ed and must be av_free()ed by the caller
+ *
+ * @note if AV_OPT_ALLOW_NULL is set in search_flags in av_opt_get, and the option has
+ * AV_OPT_TYPE_STRING or AV_OPT_TYPE_BINARY and is set to NULL, *out_val will be set
+ * to NULL instead of an allocated empty string.
  */
 int av_opt_get         (void *obj, const char *name, int search_flags, uint8_t   **out_val);
 int av_opt_get_int     (void *obj, const char *name, int search_flags, int64_t    *out_val);