AUTO_INSERT_FILTER  481 ffmpeg_filter.c         AUTO_INSERT_FILTER("-map_channel", "pan", pan_buf.str);
AUTO_INSERT_FILTER  530 ffmpeg_filter.c         AUTO_INSERT_FILTER("-vol", "volume", args);
AUTO_INSERT_FILTER  543 ffmpeg_filter.c             AUTO_INSERT_FILTER("-apad", "apad", args);