APE tags are used to store metadata in audio files (ie information about the contained content ), comparable to ID3 tags. APE offers such as ID3 (since version 2.3) the opportunity to invest alongside predefined standard fields even fields to store the information.
The APEv1 tagging system was originally developed for the Monkey's audio format. APEv1 areas have a header and data can be written only in the Fußdatenbereich a file thus, so must appear at the end of the file. In addition, only ASCII values are allowed.
Frank terminal extended the format with a header area and Unicode support, thus creating version 2 ( APEv2 ). This can be written APE tags now available with a Fußdatenbereich in a Fußdatenbereich end of the file ( recommended method ) or with a header area at the beginning of the file.
APEv2 then found for the first time in Klemm Musepack format use, but has been adopted as the primary metadata format because of its simplicity and flexibility of WavPack and OptimFROG. In version 3.99 and Monkey's Audio was converted to v2.
With the music playback software foobar2000 and MP3 files can be provided with APEv2 instead of ID3 tags, but this can cause problems in some circumstances because APE tags was not designed specifically to MP3. The string APETAGEX that initiates a APEv2 area, contains the string TAG, with the beginning of an ID3v1 area is marked. If the case occurs that this string is located at the point where a program expects a ID3v1 area, so it could be misinterpreted. Also has an ID3 " unsynchronization scheme", which ensures that ID3 metadata are not interpreted as audio. This is absent in APE, resulting in the worst case recently cracking or hissing at the end of the piece.
APEv2 tags consist of unstructured pairs of field names and values. This makes them more closely with the Vorbis comments related than ID3. Unlike Vorbis comment not each be a field to be used for a plurality of identical values , but a plurality of values are then assigned to a field name. This requires, however, that several of the same values can not be freely distributed, but are arranged one behind the other always right.
APEv2 values can be marked as "text", "binary", or "external". Thus there is also no restriction on the type of metadata such as in Vorbis comment, it can in addition to text information and binary files such as images or anything else involved. Also, a program based on the identification metadata with which it can not do anything, exclude from processing.
APEv2 supports Unicode in UTF -8 encoding for the values of the data fields, the field names are limited to a part of the ASCII character set (control characters of the range 0x00 to 0x1f are not allowed).