function bp_activity_create_summary( $content, $activity ) {
	$args = array(
		'width' => isset( $GLOBALS['content_width'] ) ? (int) $GLOBALS['content_width'] : 'medium',
	);

	// Get the WP_Post object if this activity type is a blog post.
	if ( $activity['type'] === 'new_blog_post' ) {
		$content = get_post( $activity['secondary_item_id'] );
	}

	/**
	 * Filter the class name of the media extractor when creating an Activity summary.
	 *
	 * Use this filter to change the media extractor used to extract media info for the activity item.
	 *
	 * @since 2.3.0
	 *
	 * @param string $extractor Class name.
	 * @param string $content   The content of the activity item.
	 * @param array  $activity  The data passed to bp_activity_add() or the values from an Activity obj.
	 */
	$extractor = apply_filters( 'bp_activity_create_summary_extractor_class', 'BP_Media_Extractor', $content, $activity );
	$extractor = new $extractor;

	/**
	 * Filter the arguments passed to the media extractor when creating an Activity summary.
	 *
	 * @since 2.3.0
	 *
	 * @param array              $args      Array of bespoke data for the media extractor.
	 * @param string             $content   The content of the activity item.
	 * @param array              $activity  The data passed to bp_activity_add() or the values from an Activity obj.
	 * @param BP_Media_Extractor $extractor The media extractor object.
	 */
	$args = apply_filters( 'bp_activity_create_summary_extractor_args', $args, $content, $activity, $extractor );


	// Extract media information from the $content.
	$media = $extractor->extract( $content, BP_Media_Extractor::ALL, $args );

	// If we converted $content to an object earlier, flip it back to a string.
	if ( is_a( $content, 'WP_Post' ) ) {
		$content = $content->post_content;
	}

	$para_count     = substr_count( strtolower( wpautop( $content ) ), '<p>' );
	$has_audio      = ! empty( $media['has']['audio'] )           && $media['has']['audio'];
	$has_videos     = ! empty( $media['has']['videos'] )          && $media['has']['videos'];
	$has_feat_image = ! empty( $media['has']['featured_images'] ) && $media['has']['featured_images'];
	$has_galleries  = ! empty( $media['has']['galleries'] )       && $media['has']['galleries'];
	$has_images     = ! empty( $media['has']['images'] )          && $media['has']['images'];
	$has_embeds     = false;

	// Embeds must be subtracted from the paragraph count.
	if ( ! empty( $media['has']['embeds'] ) ) {
		$has_embeds = $media['has']['embeds'] > 0;
		$para_count -= $media['has']['embeds'];
	}

	$extracted_media = array();
	$use_media_type  = '';
	$image_source    = '';

	// If it's a short article and there's an embed/audio/video, use it.
	if ( $para_count <= 3 ) {
		if ( $has_embeds ) {
			$use_media_type = 'embeds';
		} elseif ( $has_audio ) {
			$use_media_type = 'audio';
		} elseif ( $has_videos ) {
			$use_media_type = 'videos';
		}
	}

	// If not, or in any other situation, try to use an image.
	if ( ! $use_media_type && $has_images ) {
		$use_media_type = 'images';
		$image_source   = 'html';

		// Featured Image > Galleries > inline <img>.
		if ( $has_feat_image ) {
			$image_source = 'featured_images';

		} elseif ( $has_galleries ) {
			$image_source = 'galleries';
		}
	}

	// Extract an item from the $media results.
	if ( $use_media_type ) {
		if ( $use_media_type === 'images' ) {
			$extracted_media = wp_list_filter( $media[ $use_media_type ], array( 'source' => $image_source ) );
			$extracted_media = array_shift( $extracted_media );
		} else {
			$extracted_media = array_shift( $media[ $use_media_type ] );
		}

		/**
		 * Filter the results of the media extractor when creating an Activity summary.
		 *
		 * @since 2.3.0
		 *
		 * @param array  $extracted_media Extracted media item. See {@link BP_Media_Extractor::extract()} for format.
		 * @param string $content         Content of the activity item.
		 * @param array  $activity        The data passed to bp_activity_add() or the values from an Activity obj.
		 * @param array  $media           All results from the media extraction.
		 *                                See {@link BP_Media_Extractor::extract()} for format.
		 * @param string $use_media_type  The kind of media item that was preferentially extracted.
		 * @param string $image_source    If $use_media_type was "images", the preferential source of the image.
		 *                                Otherwise empty.
		 */
		$extracted_media = apply_filters(
			'bp_activity_create_summary_extractor_result',
			$extracted_media,
			$content,
			$activity,
			$media,
			$use_media_type,
			$image_source
		);
	}

	// Generate a text excerpt for this activity item (and remove any oEmbeds URLs).
	$summary = bp_create_excerpt( html_entity_decode( $content ), 225, array(
		'html' => false,
		'filter_shortcodes' => true,
		'strip_tags'        => true,
		'remove_links'      => true
	) );

	if ( $use_media_type === 'embeds' ) {
		$summary .= PHP_EOL . PHP_EOL . $extracted_media['url'];
	} elseif ( $use_media_type === 'images' ) {
		$summary .= sprintf( ' <img src="%s">', esc_url( $extracted_media['url'] ) );
	} elseif ( in_array( $use_media_type, array( 'audio', 'videos' ), true ) ) {
		$summary .= PHP_EOL . PHP_EOL . $extracted_media['original'];  // Full shortcode.
	}

	/**
	 * Filters the newly-generated summary for the activity item.
	 *
	 * @since 2.3.0
	 *
	 * @param string $summary         Activity summary HTML.
	 * @param string $content         Content of the activity item.
	 * @param array  $activity        The data passed to bp_activity_add() or the values from an Activity obj.
	 * @param array  $extracted_media Media item extracted. See {@link BP_Media_Extractor::extract()} for format.
	 */
	return apply_filters( 'bp_activity_create_summary', $summary, $content, $activity, $extracted_media );
}