For parsing XML files I use Simple XML. But for every XML file I write diffrent function, because of some XML have diffrent tags.
But how popular services parse xml? For example RSS Reader and etc. They just parse and slice additional images and videos and show it in additional block.
RSS readers only read RSS feeds. RSS feeds are XML documents with a certain standard, so to parse RSS feeds, only a certain number of standards need to be parsed. For more information see: RSS – Wikipedia
Keep in mind that RSS feeds are XML documents, but not every XML document is a RSS feed.
Reading your questing it looks like you have a variety of different XML documents with their own structure, to parse these you don’t really have any other option but to build custom parse logic for each of these.