* avoid usage of next/last buffer after flush

  (but there still something wrong when the first frame isn't keyframe)


git-svn-id: file:///var/local/repositories/ffmpeg/trunk@1403 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

libavcodec/utils.c

@@ -678,6 +678,7 @@ void avcodec_flush_buffers(AVCodecContext *avctx)
                                         || s->picture[i].type == FF_BUFFER_TYPE_USER))
             avctx->release_buffer(avctx, (AVFrame*)&s->picture[i]);
 	}
+	s->last_picture.data[0] = s->next_picture.data[0] = NULL;
         break;
     default:
         //FIXME