function wp_video_shortcode( $attr, $content = '' ) {
	global $content_width;
	$post_id = get_post() ? get_the_ID() : 0;

	static $instance = 0;
	$instance++;

	/**
	 * Filters the default video shortcode output.
	 *
	 * If the filtered output isn't empty, it will be used instead of generating
	 * the default video template.
	 *
	 * @since 3.6.0
	 *
	 * @see wp_video_shortcode()
	 *
	 * @param string $html     Empty variable to be replaced with shortcode markup.
	 * @param array  $attr     Attributes of the shortcode. @see wp_video_shortcode()
	 * @param string $content  Video shortcode content.
	 * @param int    $instance Unique numeric ID of this video shortcode instance.
	 */
	$override = apply_filters( 'wp_video_shortcode_override', '', $attr, $content, $instance );

	if ( '' !== $override ) {
		return $override;
	}

	$video = null;

	$default_types = wp_get_video_extensions();
	$defaults_atts = array(
		'src'      => '',
		'poster'   => '',
		'loop'     => '',
		'autoplay' => '',
		'preload'  => 'metadata',
		'width'    => 640,
		'height'   => 360,
		'class'    => 'wp-video-shortcode',
	);

	foreach ( $default_types as $type ) {
		$defaults_atts[ $type ] = '';
	}

	$atts = shortcode_atts( $defaults_atts, $attr, 'video' );

	if ( is_admin() ) {
		// shrink the video so it isn't huge in the admin
		if ( $atts['width'] > $defaults_atts['width'] ) {
			$atts['height'] = round( ( $atts['height'] * $defaults_atts['width'] ) / $atts['width'] );
			$atts['width']  = $defaults_atts['width'];
		}
	} else {
		// if the video is bigger than the theme
		if ( ! empty( $content_width ) && $atts['width'] > $content_width ) {
			$atts['height'] = round( ( $atts['height'] * $content_width ) / $atts['width'] );
			$atts['width']  = $content_width;
		}
	}

	$is_vimeo      = false;
	$is_youtube    = false;
	$yt_pattern    = '#^https?://(?:www\.)?(?:youtube\.com/watch|youtu\.be/)#';
	$vimeo_pattern = '#^https?://(.+\.)?vimeo\.com/.*#';

	$primary = false;
	if ( ! empty( $atts['src'] ) ) {
		$is_vimeo   = ( preg_match( $vimeo_pattern, $atts['src'] ) );
		$is_youtube = ( preg_match( $yt_pattern, $atts['src'] ) );

		if ( ! $is_youtube && ! $is_vimeo ) {
			$type = wp_check_filetype( $atts['src'], wp_get_mime_types() );

			if ( ! in_array( strtolower( $type['ext'] ), $default_types, true ) ) {
				return sprintf( '<a class="wp-embedded-video" href="%s">%s</a>', esc_url( $atts['src'] ), esc_html( $atts['src'] ) );
			}
		}

		if ( $is_vimeo ) {
			wp_enqueue_script( 'mediaelement-vimeo' );
		}

		$primary = true;
		array_unshift( $default_types, 'src' );
	} else {
		foreach ( $default_types as $ext ) {
			if ( ! empty( $atts[ $ext ] ) ) {
				$type = wp_check_filetype( $atts[ $ext ], wp_get_mime_types() );
				if ( strtolower( $type['ext'] ) === $ext ) {
					$primary = true;
				}
			}
		}
	}

	if ( ! $primary ) {
		$videos = get_attached_media( 'video', $post_id );
		if ( empty( $videos ) ) {
			return;
		}

		$video       = reset( $videos );
		$atts['src'] = wp_get_attachment_url( $video->ID );
		if ( empty( $atts['src'] ) ) {
			return;
		}

		array_unshift( $default_types, 'src' );
	}

	/**
	 * Filters the media library used for the video shortcode.
	 *
	 * @since 3.6.0
	 *
	 * @param string $library Media library used for the video shortcode.
	 */
	$library = apply_filters( 'wp_video_shortcode_library', 'mediaelement' );
	if ( 'mediaelement' === $library && did_action( 'init' ) ) {
		wp_enqueue_style( 'wp-mediaelement' );
		wp_enqueue_script( 'wp-mediaelement' );
		wp_enqueue_script( 'mediaelement-vimeo' );
	}

	// Mediaelement has issues with some URL formats for Vimeo and YouTube, so
	// update the URL to prevent the ME.js player from breaking.
	if ( 'mediaelement' === $library ) {
		if ( $is_youtube ) {
			// Remove `feature` query arg and force SSL - see #40866.
			$atts['src'] = remove_query_arg( 'feature', $atts['src'] );
			$atts['src'] = set_url_scheme( $atts['src'], 'https' );
		} elseif ( $is_vimeo ) {
			// Remove all query arguments and force SSL - see #40866.
			$parsed_vimeo_url = wp_parse_url( $atts['src'] );
			$vimeo_src        = 'https://' . $parsed_vimeo_url['host'] . $parsed_vimeo_url['path'];

			// Add loop param for mejs bug - see #40977, not needed after #39686.
			$loop        = $atts['loop'] ? '1' : '0';
			$atts['src'] = add_query_arg( 'loop', $loop, $vimeo_src );
		}
	}

	/**
	 * Filters the class attribute for the video shortcode output container.
	 *
	 * @since 3.6.0
	 * @since 4.9.0 The `$atts` parameter was added.
	 *
	 * @param string $class CSS class or list of space-separated classes.
	 * @param array  $atts  Array of video shortcode attributes.
	 */
	$atts['class'] = apply_filters( 'wp_video_shortcode_class', $atts['class'], $atts );

	$html_atts = array(
		'class'    => $atts['class'],
		'id'       => sprintf( 'video-%d-%d', $post_id, $instance ),
		'width'    => absint( $atts['width'] ),
		'height'   => absint( $atts['height'] ),
		'poster'   => esc_url( $atts['poster'] ),
		'loop'     => wp_validate_boolean( $atts['loop'] ),
		'autoplay' => wp_validate_boolean( $atts['autoplay'] ),
		'preload'  => $atts['preload'],
	);

	// These ones should just be omitted altogether if they are blank
	foreach ( array( 'poster', 'loop', 'autoplay', 'preload' ) as $a ) {
		if ( empty( $html_atts[ $a ] ) ) {
			unset( $html_atts[ $a ] );
		}
	}

	$attr_strings = array();
	foreach ( $html_atts as $k => $v ) {
		$attr_strings[] = $k . '="' . esc_attr( $v ) . '"';
	}

	$html = '';
	if ( 'mediaelement' === $library && 1 === $instance ) {
		$html .= "<!--[if lt IE 9]><script>document.createElement('video');</script><![endif]-->\n";
	}
	$html .= sprintf( '<video %s controls="controls">', join( ' ', $attr_strings ) );

	$fileurl = '';
	$source  = '<source type="%s" src="%s" />';
	foreach ( $default_types as $fallback ) {
		if ( ! empty( $atts[ $fallback ] ) ) {
			if ( empty( $fileurl ) ) {
				$fileurl = $atts[ $fallback ];
			}
			if ( 'src' === $fallback && $is_youtube ) {
				$type = array( 'type' => 'video/youtube' );
			} elseif ( 'src' === $fallback && $is_vimeo ) {
				$type = array( 'type' => 'video/vimeo' );
			} else {
				$type = wp_check_filetype( $atts[ $fallback ], wp_get_mime_types() );
			}
			$url   = add_query_arg( '_', $instance, $atts[ $fallback ] );
			$html .= sprintf( $source, $type['type'], esc_url( $url ) );
		}
	}

	if ( ! empty( $content ) ) {
		if ( false !== strpos( $content, "\n" ) ) {
			$content = str_replace( array( "\r\n", "\n", "\t" ), '', $content );
		}
		$html .= trim( $content );
	}

	if ( 'mediaelement' === $library ) {
		$html .= wp_mediaelement_fallback( $fileurl );
	}
	$html .= '</video>';

	$width_rule = '';
	if ( ! empty( $atts['width'] ) ) {
		$width_rule = sprintf( 'width: %dpx;', $atts['width'] );
	}
	$output = sprintf( '<div style="%s" class="wp-video">%s</div>', $width_rule, $html );

	/**
	 * Filters the output of the video shortcode.
	 *
	 * @since 3.6.0
	 *
	 * @param string $output  Video shortcode HTML output.
	 * @param array  $atts    Array of video shortcode attributes.
	 * @param string $video   Video file.
	 * @param int    $post_id Post ID.
	 * @param string $library Media library used for the video shortcode.
	 */
	return apply_filters( 'wp_video_shortcode', $output, $atts, $video, $post_id, $library );
}