lavc: make avcodec_close() work properly on unopened codecs.

I.e. free the priv_data and other stuff allocated in
avcodec_alloc_context3() and not segfault.

(cherry picked from commit 0e72ad95f9fef6a6b8ae55e47339a5c40526502f)

1 files changed, 11 insertions, 1 deletions

diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
index 6db34fa78e..95e14d7c2d 100644
--- a/libavcodec/avcodec.h
+++ b/libavcodec/avcodec.h
@@ -3912,7 +3912,8 @@ AVCodecContext *avcodec_alloc_context2(enum AVMediaType);
 
 /**
  * Allocate an AVCodecContext and set its fields to default values.  The
- * resulting struct can be deallocated by simply calling av_free().
+ * resulting struct can be deallocated by calling avcodec_close() on it followed
+ * by av_free().
  *
  * @param codec if non-NULL, allocate private data and initialize defaults
  *              for the given codec. It is illegal to then call avcodec_open2()
@@ -4343,6 +4344,15 @@ int avcodec_encode_video(AVCodecContext *avctx, uint8_t *buf, int buf_size,
 int avcodec_encode_subtitle(AVCodecContext *avctx, uint8_t *buf, int buf_size,
                             const AVSubtitle *sub);
 
+/**
+ * Close a given AVCodecContext and free all the data associated with it
+ * (but not the AVCodecContext itself).
+ *
+ * Calling this function on an AVCodecContext that hasn't been opened will free
+ * the codec-specific data allocated in avcodec_alloc_context3() /
+ * avcodec_get_context_defaults3() with a non-NULL codec. Subsequent calls will
+ * do nothing.
+ */
 int avcodec_close(AVCodecContext *avctx);
 
 /**