Make avfilter_unref_buffer() accept a NULL parameter.

Originally committed as revision 26373 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavfilter/avfilter.c

@@ -70,6 +70,8 @@ AVFilterBufferRef *avfilter_ref_buffer(AVFilterBufferRef *ref, int pmask)
 
 void avfilter_unref_buffer(AVFilterBufferRef *ref)
 {
+    if (!ref)
+        return;
     if (!(--ref->buf->refcount))
         ref->buf->free(ref->buf);
     av_free(ref->video);

libavfilter/avfilter.h

@@ -28,7 +28,7 @@
 
 #define LIBAVFILTER_VERSION_MAJOR  1
 #define LIBAVFILTER_VERSION_MINOR 73
-#define LIBAVFILTER_VERSION_MICRO  1
+#define LIBAVFILTER_VERSION_MICRO  2
 
 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \
                                                LIBAVFILTER_VERSION_MINOR, \
@@ -177,7 +177,7 @@ AVFilterBufferRef *avfilter_ref_buffer(AVFilterBufferRef *ref, int pmask);
  * Remove a reference to a buffer. If this is the last reference to the
  * buffer, the buffer itself is also automatically freed.
  *
- * @param ref reference to the buffer
+ * @param ref reference to the buffer, may be NULL
  */
 void avfilter_unref_buffer(AVFilterBufferRef *ref);