#isU', $content, $matches, PREG_SET_ORDER);
		foreach ($matches as $match) {
			$attrs = Utility::parse_attr($match[1]);

			if ( empty( $attrs['src'] ) ) {
				continue;
			}

			if ( false !== strpos( $attrs['src'], 'base64' ) || 0 === strpos( $attrs['src'], 'data:' ) ) {
				self::debug2( 'lazyload bypassed base64 img' );
				continue;
			}

			if ( false !== strpos( $attrs['src'], '{' ) ) {
				self::debug2( 'image src has {} ' . $attrs['src'] );
				continue;
			}

			// If the src contains VPI filename, then preload it.
			if ( ! Utility::str_hit_array( $attrs['src'], $vpi_files ) ) {
				continue;
			}

			self::debug2( 'VPI preload found and matched: ' . $attrs['src'] );

			$this->_vpi_preload_list[] = $attrs['src'];

			// Add attributes fetchpriority="high" and decode="sync"
			// after WP 6.3.0 use: wp_img_tag_add_loading_optimization_attrs().
			$new_html                 = [];
			$attrs[ 'fetchpriority' ] = 'high';
			$attrs[ 'decoding' ]      = 'sync';
			// create html with new attributes.
			foreach ( $attrs as $k => $attr ) {
				$new_html[] = $k . '="' . $attr . '"';
			}

			if ( $new_html ) {
				$vpi_fp_search[]  = $match[1];
				$vpi_fp_replace[] = implode( ' ', $new_html);
			}
		}

		// if VPI fetchpriority changes, do the replacement
		if ( $vpi_fp_search && $vpi_fp_replace ) {
			$this->content = str_replace( $vpi_fp_search, $vpi_fp_replace, $this->content );
		}
		unset( $vpi_fp_search );
		unset( $vpi_fp_replace );
	}

	/**
	 * Parse img src.
	 *
	 * @since  1.4
	 * @access private
	 * @return array{0:array,1:array,2:array}  All the src & related raw html list with placeholders.
	 */
	private function _parse_img() {
		/**
		 * Exclude list.
		 *
		 * @since 1.5
		 * @since 2.7.1 Changed to array.
		 */
		$excludes = apply_filters( 'litespeed_media_lazy_img_excludes', $this->conf( Base::O_MEDIA_LAZY_EXC ) );

		$cls_excludes   = apply_filters( 'litespeed_media_lazy_img_cls_excludes', $this->conf( Base::O_MEDIA_LAZY_CLS_EXC ) );
		$cls_excludes[] = 'skip-lazy'; // https://core.trac.wordpress.org/ticket/44427

		$src_list         = [];
		$html_list        = [];
		$placeholder_list = [];

		$content = preg_replace(
			[
				'#<!--.*-->#sU',
				'#<noscript([^>]*)>.*</noscript>#isU',
				'#<script([^>]*)>.*</script>#isU', // Remove script to avoid false matches and warnings, when image size detection is turned ON.
			],
			'',
			$this->content
		);
		/**
		 * Exclude parent classes.
		 *
		 * @since 3.0
		 */
		$parent_cls_exc = apply_filters( 'litespeed_media_lazy_img_parent_cls_excludes', $this->conf( Base::O_MEDIA_LAZY_PARENT_CLS_EXC ) );
		if ( $parent_cls_exc ) {
			self::debug2( 'Lazyload Class excludes', $parent_cls_exc );
			foreach ( $parent_cls_exc as $v ) {
				$content = preg_replace('#<(\w+) [^>]*class=(\'|")[^\'"]*' . preg_quote($v, '#') . '[^\'"]*\2[^>]*>.*</\1>#sU', '', $content);
			}
		}

		$add_missing_sizes = ( defined( 'LITESPEED_GUEST_OPTM' ) || $this->conf( Base::O_MEDIA_ADD_MISSING_SIZES ) )
			&& apply_filters( 'litespeed_media_add_missing_sizes', true );

		preg_match_all( '#<img\s+([^>]+)/?>#isU', $content, $matches, PREG_SET_ORDER );
		foreach ( $matches as $match ) {
			$attrs = Utility::parse_attr( $match[1] );

			if ( empty( $attrs['src'] ) ) {
				continue;
			}

			/**
			 * Add src validation to bypass base64 img src.
			 *
			 * @since 1.6
			 */
			if ( false !== strpos( $attrs['src'], 'base64' ) || 0 === strpos( $attrs['src'], 'data:' ) ) {
				self::debug2( 'lazyload bypassed base64 img' );
				continue;
			}

			self::debug2( 'lazyload found: ' . $attrs['src'] );

			if (
				! empty( $attrs['data-no-lazy'] ) ||
				! empty( $attrs['data-skip-lazy'] ) ||
				! empty( $attrs['data-lazyloaded'] ) ||
				! empty( $attrs['data-src'] ) ||
				! empty( $attrs['data-srcset'] )
			) {
				self::debug2( 'bypassed' );
				continue;
			}

			$hit = ! empty( $attrs['class'] ) ? Utility::str_hit_array( $attrs['class'], $cls_excludes ) : false;
			if ( $hit ) {
				self::debug2( 'lazyload image cls excludes [hit] ' . $hit );
				continue;
			}

			/**
			 * Exclude from lazyload by setting.
			 *
			 * @since 1.5
			 */
			if ( $excludes && Utility::str_hit_array( $attrs['src'], $excludes ) ) {
				self::debug2( 'lazyload image exclude ' . $attrs['src'] );
				continue;
			}

			/**
			 * Excludes invalid image src from buddypress avatar crop.
			 *
			 * @see https://wordpress.org/support/topic/lazy-load-breaking-buddypress-upload-avatar-feature
			 * @since 3.0
			 */
			if ( false !== strpos( $attrs['src'], '{' ) ) {
				self::debug2( 'image src has {} ' . $attrs['src'] );
				continue;
			}

			// to avoid multiple replacement.
			if ( in_array( $match[0], $html_list, true ) ) {
				continue;
			}

			// Add missing dimensions.
			if ( $add_missing_sizes ) {
				if ( empty( $attrs['width'] ) || 'auto' === $attrs['width'] || empty( $attrs['height'] ) || 'auto' === $attrs['height'] ) {
					self::debug( '⚠️ Missing sizes for image [src] ' . $attrs['src'] );
					$dimensions = $this->_detect_dimensions( $attrs['src'] );
					if ( $dimensions ) {
						$ori_width  = $dimensions[0];
						$ori_height = $dimensions[1];
						// Calculate height based on width.
						if ( ! empty( $attrs['width'] ) && 'auto' !== $attrs['width'] ) {
							$ori_height = (int) ( ( $ori_height * (int) $attrs['width'] ) / max( 1, $ori_width ) );
						} elseif ( ! empty( $attrs['height'] ) && 'auto' !== $attrs['height'] ) {
							$ori_width = (int) ( ( $ori_width * (int) $attrs['height'] ) / max( 1, $ori_height ) );
						}

						// Remove existing width/height, then append new values
						$inner    = Utility::remove_attr( $match[1], 'width' );
						$inner    = Utility::remove_attr( $inner, 'height' );
						$new_html = '<img ' . $inner . ' width="' . (int) $ori_width . '" height="' . (int) $ori_height . '" />';
						self::debug( 'Add missing sizes ' . $ori_width . 'x' . $ori_height . ' to ' . $attrs['src'] );
						$this->content   = str_replace( $match[0], $new_html, $this->content );
						$match[0]        = $new_html;
						$attrs['width']  = $ori_width;
						$attrs['height'] = $ori_height;
					}
				}
			}

			$placeholder = false;
			if ( ! empty( $attrs['width'] ) && 'auto' !== $attrs['width'] && ! empty( $attrs['height'] ) && 'auto' !== $attrs['height'] ) {
				$placeholder = (int) $attrs['width'] . 'x' . (int) $attrs['height'];
			}

			$src_list[]         = $attrs['src'];
			$html_list[]        = $match[0];
			$placeholder_list[] = $placeholder;
		}

		return [ $src_list, $html_list, $placeholder_list ];
	}

	/**
	 * Detect the original sizes.
	 *
	 * @since 4.0
	 *
	 * @param string $src Source URL/path.
	 * @return array|false getimagesize array or false.
	 */
	private function _detect_dimensions( $src ) {
		$pathinfo = Utility::is_internal_file( $src );
		if ( $pathinfo ) {
			$src = $pathinfo[0];
		} elseif ( apply_filters( 'litespeed_media_ignore_remote_missing_sizes', false ) ) {
			return false;
		}

		if ( 0 === strpos( $src, '//' ) ) {
			$src = 'https:' . $src;
		}

		try {
			$sizes = getimagesize( $src );
		} catch ( \Exception $e ) {
			return false;
		}

		if ( ! empty( $sizes[0] ) && ! empty( $sizes[1] ) ) {
			return $sizes;
		}

		return false;
	}

	/**
	 * Parse iframe src.
	 *
	 * @since  1.4
	 * @access private
	 * @return array All the related raw html list (full <iframe> tags).
	 */
	private function _parse_iframe() {
		$cls_excludes   = apply_filters( 'litespeed_media_iframe_lazy_cls_excludes', $this->conf( Base::O_MEDIA_IFRAME_LAZY_CLS_EXC ) );
		$cls_excludes[] = 'skip-lazy'; // https://core.trac.wordpress.org/ticket/44427

		$html_list = [];

		$content = preg_replace( '#<!--.*-->#sU', '', $this->content );

		/**
		 * Exclude parent classes.
		 *
		 * @since 3.0
		 */
		$parent_cls_exc = apply_filters( 'litespeed_media_iframe_lazy_parent_cls_excludes', $this->conf( Base::O_MEDIA_IFRAME_LAZY_PARENT_CLS_EXC ) );
		if ( $parent_cls_exc ) {
			self::debug2( 'Iframe Lazyload Class excludes', $parent_cls_exc );
			foreach ( $parent_cls_exc as $v ) {
				$content = preg_replace('#<(\w+) [^>]*class=(\'|")[^\'"]*' . preg_quote($v, '#') . '[^\'"]*\2[^>]*>.*</\1>#sU', '', $content);
			}
		}

		preg_match_all( '#<iframe \s*([^>]+)></iframe>#isU', $content, $matches, PREG_SET_ORDER );
		foreach ( $matches as $match ) {
			$attrs = Utility::parse_attr( $match[1] );

			if ( empty( $attrs['src'] ) ) {
				continue;
			}

			self::debug2( 'found iframe: ' . $attrs['src'] );

			if ( ! empty( $attrs['data-no-lazy'] ) || ! empty( $attrs['data-skip-lazy'] ) || ! empty( $attrs['data-lazyloaded'] ) || ! empty( $attrs['data-src'] ) ) {
				self::debug2( 'bypassed' );
				continue;
			}

			$hit = ! empty( $attrs['class'] ) ? Utility::str_hit_array( $attrs['class'], $cls_excludes ) : false;
			if ( $hit ) {
				self::debug2( 'iframe lazyload cls excludes [hit] ' . $hit );
				continue;
			}

			if ( apply_filters( 'litespeed_iframe_lazyload_exc', false, $attrs['src'] ) ) {
				self::debug2( 'bypassed by filter' );
				continue;
			}

			// to avoid multiple replacement.
			if ( in_array( $match[0], $html_list, true ) ) {
				continue;
			}

			$html_list[] = $match[0];
		}

		return $html_list;
	}

	/**
	 * Replace image src to webp/avif in buffer.
	 *
	 * @since  1.6.2
	 * @access private
	 *
	 * @param string $content HTML content.
	 * @return string Modified content.
	 */
	private function _replace_buffer_img_webp( $content ) {
		/**
		 * Added custom element & attribute support.
		 *
		 * @since 2.2.2
		 */
		$webp_ele_to_check = $this->conf( Base::O_IMG_OPTM_WEBP_ATTR );

		foreach ( $webp_ele_to_check as $v ) {
			if ( ! $v || false === strpos( $v, '.' ) ) {
				self::debug2( 'buffer_webp no . attribute ' . $v );
				continue;
			}

			self::debug2( 'buffer_webp attribute ' . $v );

			$v    = explode( '.', $v );
			$attr = preg_quote( $v[1], '#' );
			if ( $v[0] ) {
				$pattern = '#<' . preg_quote( $v[0], '#' ) . '([^>]+)' . $attr . '=([\'"])(.+)\2#iU';
			} else {
				$pattern = '# ' . $attr . '=([\'"])(.+)\1#iU';
			}

			preg_match_all( $pattern, $content, $matches );

			foreach ( $matches[ $v[0] ? 3 : 2 ] as $k2 => $url ) {
				// Check if is a DATA-URI.
				if ( false !== strpos( $url, 'data:image' ) ) {
					continue;
				}

				$url2 = $this->replace_webp( $url );
				if ( ! $url2 ) {
					continue;
				}

				if ( $v[0] ) {
					$html_snippet = sprintf( '<' . $v[0] . '%1$s' . $v[1] . '=%2$s', $matches[1][ $k2 ], $matches[2][ $k2 ] . $url2 . $matches[2][ $k2 ] );
				} else {
					$html_snippet = sprintf( ' ' . $v[1] . '=%1$s', $matches[1][ $k2 ] . $url2 . $matches[1][ $k2 ] );
				}

				$content = str_replace( $matches[0][ $k2 ], $html_snippet, $content );
			}
		}

		// parse srcset.
		// todo: should apply this to cdn too.
		if ( ( defined( 'LITESPEED_GUEST_OPTM' ) || $this->conf( Base::O_IMG_OPTM_WEBP_REPLACE_SRCSET ) ) && $this->webp_support() ) {
			$content = Utility::srcset_replace( $content, [ $this, 'replace_webp' ] );
		}

		// Replace background-image.
		if ( ( defined( 'LITESPEED_GUEST_OPTM' ) || $this->conf( Base::O_IMG_OPTM_WEBP ) ) && $this->webp_support() ) {
			$content = $this->replace_background_webp( $content );
		}

		return $content;
	}

	/**
	 * Replace background image in inline styles and JSON blobs.
	 *
	 * @since 4.0
	 *
	 * @param string $content HTML content.
	 * @return string Modified content.
	 */
	public function replace_background_webp( $content ) {
		self::debug2( 'Start replacing background WebP/AVIF.' );

		// Handle Elementor's data-settings JSON encoded background-images.
		$content = $this->replace_urls_in_json( $content );

		preg_match_all( '#url\(([^)]+)\)#iU', $content, $matches );
		foreach ( $matches[1] as $k => $url ) {
			// Check if is a DATA-URI.
			if ( false !== strpos( $url, 'data:image' ) ) {
				continue;
			}

			/**
			 * Support quotes in src `background-image: url('src')`.
			 *
			 * @since 2.9.3
			 */
			$url = trim( $url, '\'"' );

			// Fix Elementor's Slideshow unusual background images like  style="background-image: url(&quot;https://xxxx.png&quot;);"
			if ( 0 === strpos( $url, '&quot;' ) && '&quot;' === substr( $url, -6 ) ) {
				$url = substr( $url, 6, -6 );
			}

			$url2 = $this->replace_webp( $url );
			if ( ! $url2 ) {
				continue;
			}

			$html_snippet = str_replace( $url, $url2, $matches[0][ $k ] );
			$content      = str_replace( $matches[0][ $k ], $html_snippet, $content );
		}

		return $content;
	}

	/**
	 * Replace images in json data settings attributes.
	 *
	 * @since 6.2
	 *
	 * @param string $content HTML content to scan and modify.
	 * @return string Modified content with replaced URLs inside JSON attributes.
	 */
	public function replace_urls_in_json( $content ) {
		$pattern      = '/data-settings="(.*?)"/i';
		$parent_class = $this;

		preg_match_all( $pattern, $content, $matches, PREG_SET_ORDER );

		foreach ( $matches as $match ) {
			// Decode HTML entities in the JSON string.
			$json_string = html_entity_decode( $match[1] );

			$json_data = \json_decode( $json_string, true );

			if ( JSON_ERROR_NONE === json_last_error() && is_array( $json_data ) ) {
				$did_webp_replace = false;

				array_walk_recursive(
					$json_data,
                    /**
                     * Replace URLs in JSON data recursively.
                     *
                     * @param mixed  $item Value (modified in place).
                     * @param string $key  Array key.
                     */
					function ( &$item, $key ) use ( &$did_webp_replace, $parent_class ) {
						if ( 'url' === $key ) {
							$item_image = $parent_class->replace_webp( $item );
							if ( $item_image ) {
								$item             = $item_image;
								$did_webp_replace = true;
							}
						}
					}
				);

				if ( $did_webp_replace ) {
					$new_json_string = wp_json_encode( $json_data );

					// Force double_encode; esc_attr() would leave a literal `&quot;` intact and the browser decodes it back into a quote.
					$new_json_string = htmlspecialchars( $new_json_string, ENT_QUOTES, 'UTF-8', true );

					// Replace the whole attribute, not the bare value, which may also appear in inline JS. Prefix sliced to keep original casing.
					$attr_prefix = substr( $match[0], 0, strlen( $match[0] ) - strlen( $match[1] ) - 1 );
					$content     = str_replace( $match[0], $attr_prefix . $new_json_string . '"', $content );
				}
			}
		}

		return $content;
	}

	/**
	 * Replace internal image src to webp or avif.
	 *
	 * @since  1.6.2
	 * @access public
	 *
	 * @param string $url Image URL.
	 * @return string|false Replaced URL or false if not applicable.
	 */
	public function replace_webp( $url ) {
		if ( ! $this->webp_support() ) {
			self::debug2( 'No next generation format chosen in setting, bypassed' );
			return false;
		}

		// Parse extension from URL path.
		$url_path = wp_parse_url( $url, PHP_URL_PATH );
		$postfix  = $url_path ? strtolower( pathinfo( $url_path, PATHINFO_EXTENSION ) ) : '';
		// Only process image formats that can be converted to WebP/AVIF.
		if ( ! in_array( $postfix, [ 'jpg', 'jpeg', 'png', 'gif' ], true ) ) {
			self::debug2( 'not convertible format, bypassed' );
			return false;
		}

		self::debug2( $this->_sys_format . ' replacing: ' . substr( $url, 0, 200 ) . ' [.' . $postfix . ']' );

		/**
		 * WebP/AVIF API hook.
		 * NOTE: As $url may contain query strings, check filters which may parse_url before appending format.
		 *
		 * @since  2.9.5
		 * @see  #751737 - API docs for WebP generation
		 */
		$ori_check = apply_filters( 'litespeed_media_check_ori', Utility::is_internal_file( $url ), $url );
		if ( $ori_check ) {
			// check if has webp/avif file.
			$has_next = apply_filters( 'litespeed_media_check_webp', Utility::is_internal_file( $url, $this->_sys_format ), $url );
			if ( $has_next ) {
				$url .= '.' . $this->_sys_format;
			} else {
				self::debug2( '-no WebP or AVIF file, bypassed' );
				return false;
			}
		} else {
			self::debug2( '-no file, bypassed' );
			return false;
		}

		self::debug2( '- replaced to: ' . $url );

		return $url;
	}

	/**
	 * Hook to wp_get_attachment_image_src.
	 *
	 * @since  1.6.2
	 * @access public
	 *
	 * @param  array $img The URL, width, height array.
	 * @return array
	 */
	public function webp_attach_img_src( $img ) {
		self::debug2( 'changing attach src: ' . $img[0] );
		$url = $img ? $this->replace_webp( $img[0] ) : false;
		if ( $url ) {
			$img[0] = $url;
		}
		return $img;
	}

	/**
	 * Try to replace img url.
	 *
	 * @since  1.6.2
	 * @access public
	 *
	 * @param  string $url Image URL.
	 * @return string
	 */
	public function webp_url( $url ) {
		$url2 = $url ? $this->replace_webp( $url ) : false;
		if ( $url2 ) {
			$url = $url2;
		}
		return $url;
	}

	/**
	 * Hook to replace WP responsive images.
	 *
	 * @since  1.6.2
	 * @access public
	 *
	 * @param  array $srcs Srcset array.
	 * @return array
	 */
	public function webp_srcset( $srcs ) {
		if ( $srcs ) {
			foreach ( $srcs as $w => $data ) {
				$url = $this->replace_webp( $data['url'] );
				if ( ! $url ) {
					continue;
				}
				$srcs[ $w ]['url'] = $url;
			}
		}
		return $srcs;
	}
}