bp_media_update_media_meta( $content,  $user_id,  $activity_id )

function bp_media_update_media_meta( $content, $user_id, $activity_id ) {

	if ( ! isset( $_POST['media'] ) || empty( $_POST['media'] ) ) {
		return false;
	}

	$media_list = $_POST['media'];

	if ( ! empty( $media_list ) ) {
		$media_ids = array();
		foreach ( $media_list as $media_index => $media ) {

			// remove actions to avoid infinity loop
			remove_action( 'bp_activity_posted_update', 'bp_media_update_media_meta', 10, 3 );
			remove_action( 'bp_groups_posted_update', 'bp_media_groups_update_media_meta', 10, 4 );

			// make an activity for the media
			$a_id = bp_activity_post_update( array( 'hide_sitewide' => true, 'privacy' => 'media' ) );

			if ( $a_id ) {
				// update activity meta
				bp_activity_update_meta( $a_id, 'bp_media_activity', '1' );
			}

			add_action( 'bp_activity_posted_update', 'bp_media_update_media_meta', 10, 3 );
			add_action( 'bp_groups_posted_update', 'bp_media_groups_update_media_meta', 10, 4 );

			$title         = ! empty( $media['name'] ) ? $media['name'] : ' ';
			$album_id      = ! empty( $media['album_id'] ) ? $media['album_id'] : 0;
			$privacy       = ! empty( $media['privacy'] ) ? $media['privacy'] : 'public';
			$attachment_id = ! empty( $media['id'] ) ? $media['id'] : 0;
			$menu_order    = ! empty( $media['menu_order'] ) ? $media['menu_order'] : $media_index;

			$media_id = bp_media_add(
				array(
					'title'         => $title,
					'album_id'      => $album_id,
					'activity_id'   => $a_id,
					'privacy'       => $privacy,
					'attachment_id' => $attachment_id,
					'menu_order'    => $menu_order,
				)
			);

			if ( $media_id ) {
				$media_ids[] = $media_id;

				//save media is saved in attahchment
				update_post_meta( $attachment_id, 'bp_media_saved', true );

				//save media meta for activity
				if ( ! empty( $activity_id ) && ! empty( $attachment_id ) ) {
					update_post_meta( $attachment_id, 'bp_media_parent_activity_id', $activity_id );
					update_post_meta( $attachment_id, 'bp_media_activity_id', $a_id );
				}
			}
		}

		$media_ids = implode( ',', $media_ids );

		//save media meta for activity
		if ( ! empty( $activity_id ) ) {
			bp_activity_update_meta( $activity_id, 'bp_media_ids', $media_ids );
		}
	}
}