The main class in the ID3v2 implementation. .
This is the main class in the ID3v2 implementation. It serves two functions. This first, as is obvious from the public API, is to provide a container for the other ID3v2 related classes. In addition, through the read() and parse() protected methods, it provides the most basic level of parsing. In these methods the ID3v2 tag is extracted from the file and split into data components.ID3v2 tags have several parts, TagLib attempts to provide an interface for them all. header(), footer() and extendedHeader() corespond to those data structures in the ID3v2 standard and the APIs for the classes that they return attempt to reflect this.Also ID3v2 tags are built up from a list of frames, which are in turn have a header and a list of fields. TagLib provides two ways of accessing the list of frames that are in a given ID3v2 tag. The first is simply via the frameList() method. This is just a list of pointers to the frames. The second is a map from the frame type — i.e. "COMM" for comments — and a list of frames of that type. (In some cases ID3v2 allows for multiple frames of the same type, hence this being a map to a list rather than just a map to an individual frame.)More information on the structure of frames can be found in the ID3v2::Frame class.read() and parse() pass binary data to the other ID3v2 class structures, they do not handle parsing of flags or fields, for instace. Those are handled by similar functions within those classes.All pointers to data structures within the tag will become invalid when the tag is destroyed. Dealing with the nasty details of ID3v2 is not for the faint of heart and should not be done without much meditation on the spec. It's rather long, but if you're planning on messing with this class and others that deal with the details of ID3v2 (rather than the nice, safe, abstract TagLib::Tag and friends), it's worth your time to familiarize yourself with said spec (which is distrubuted with the TagLib sources). TagLib tries to do most of the work, but with a little luck, you can still convince it to generate invalid ID3v2 tags. The APIs for ID3v2 assume a working knowledge of ID3v2 structure. You're been warned.