avfilter/audio, video: Remove references to avfilter_unref_buffer()

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

libavfilter/audio.h

@@ -37,8 +37,7 @@ AVFrame *ff_null_get_audio_buffer(AVFilterLink *link, int nb_samples);
  * @param link           the output link to the filter from which the buffer will
  *                       be requested
  * @param nb_samples     the number of samples per channel
- * @return               A reference to the samples. This must be unreferenced with
- *                       avfilter_unref_buffer when you are finished with it.
+ * @return               on success an AVFrame owned by the caller, NULL on error
  */
 AVFrame *ff_get_audio_buffer(AVFilterLink *link, int nb_samples);
 

libavfilter/video.h

@@ -33,8 +33,7 @@ AVFrame *ff_null_get_video_buffer(AVFilterLink *link, int w, int h);
  *              be requested
  * @param w     the minimum width of the buffer to allocate
  * @param h     the minimum height of the buffer to allocate
- * @return      A reference to the buffer. This must be unreferenced with
- *              avfilter_unref_buffer when you are finished with it.
+ * @return      on success, an AVFrame owned by the caller, NULL on error
  */
 AVFrame *ff_get_video_buffer(AVFilterLink *link, int w, int h);