APE day

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Structure of the APEv2 tags
Header data (32 bytes)
day 1
day 2
...
Day n
Footer (32 bytes)

APE tags are used to store metadata in audio files ( i.e. information about the content they contain), comparable to ID3 tags . Like ID3 (version 2.3 and higher), APE offers the option of creating fields for storing information in addition to predefined standard fields.

history

APEv1

The APEv1 tagging system was originally developed for the Monkey's audio format. APEv1 areas have no header data and can therefore only be written to the footer data area of a file, so they must be at the end of the file. In addition, only ASCII values ​​are allowed.

APEv2

Frank Klemm expanded the format to include a header data area and Unicode support, creating version 2 (APEv2). This means that APE tags can now be written either with a footer data area in a footer data area at the end of the file (recommended variant) or with a header data area at the beginning of the file.

APEv2 was then used for the first time in Klemm's Musepack format, but was also adopted as the primary metadata format by WavPack and OptimFROG because of its simplicity and flexibility . In version 3.99, Monkey's Audio was also converted to v2.

With the music playback software foobar2000 , MP3 files can also be provided with APEv2 instead of ID3 tags, but this can lead to problems under certain circumstances, as APE tags were not specially designed with MP3 in mind. The character string APETAGEX , which introduces an APEv2 area, contains the character string TAG , with which the beginning of an ID3v1 area is identified. If the case occurs that this character string is at the point where a program expects an ID3v1 area, this could lead to misinterpretations. ID3 also has an "unsynchronization scheme" which ensures that ID3 metadata is not interpreted as audio. This is absent with APE, which in the worst case leads to brief crackling or noise at the end of the piece.

features

APEv2 tags consist of unstructured pairs of field names and values. This makes them more closely related to Vorbis comments than to ID3. In contrast to Vorbis comment, a field identifier is not used for several similar values, but several values ​​are assigned to one field name. However, this means that several values ​​with the same name cannot be freely distributed, but are always arranged directly one after the other.

APEv2 values ​​can be marked as “text”, “binary”, or “external”. There is also no restriction on the type of metadata, as is the case with Vorbis comment; in addition to text information, binary data such as images or the like can also be included. A program can also use the identifier to exclude metadata from processing that it cannot do anything with.

APEv2 supports Unicode in UTF-8 coding for the values ​​of the data fields, the field names are limited to a part of the ASCII character set (control characters from the range 0x00 to 0x1f are not permitted).

See also

Web links

swell

  1. http://wiki.hydrogenaudio.org/index.php?title=APE_key Details about the APE key (English)