WordPress at a glance
filter is not described

the_content_feed filter-hook . WP 2.9.0

Filters the post content for use in feeds.


add_filter( 'the_content_feed', 'filter_function_name_107', 10, 2 );
function filter_function_name_107( $content, $feed_type ){
	// filter...

	return $content;
The current post content.
Type of feed. Possible values include 'rss2', 'atom'.
Default: 'rss2'

Where the hook is called

wp-includes/feed.php 202
return apply_filters( 'the_content_feed', $content, $feed_type );

Where the hook is used (in WP core)

wp-includes/default-filters.php 219
add_filter( 'the_content_feed', 'wp_staticize_emoji' );
wp-includes/default-filters.php 220
add_filter( 'the_content_feed', '_oembed_filter_feed_content' );