Question

the objective is to extract metadata from file types. I know about these:
TagLib for audio files
Exiv2 for images (but this is for C++)

1. I’m not sure about TagLib working properly for C programs. I could not find something of that order too.
2. Exiv2 is a C++ library.

Do you know any libraries I can use with C programs?
Or if there are other libraries, how do I interface them with my C program?

Answer 1

• The libexif C EXIF library is a library
  written in pure portable C. It reads and writes EXIF metainformation
  from and to image files.
• GNU Libextractor is a library used to
  extract meta data from files. GNU libextractor uses helper-libraries
  (plugins) to perform the actual extraction. As a result, GNU
  libextractor can be extended simply by installing additional plugins.
  Currently, libextractor supports the following formats: HTML, MAN,
  PS, DVI, OLE2 (DOC, XLS, PPT), OpenOffice (sxw), StarOffice (sdw),
  FLAC, MP3 (ID3v1 and ID3v2), OGG, WAV, S3M (Scream Tracker 3), XM
  (eXtended Module), IT (Impulse Tracker), NSF(E) (NES music), SID (C64
  music), EXIV2, JPEG, GIF, PNG, TIFF, DEB, RPM, TAR(.GZ), LZH, LHA,
  RAR, ZIP, CAB, 7-ZIP, AR, MTREE, PAX, CPIO, ISO9660, SHAR, RAW, XAR
  FLV, REAL, RIFF (AVI), MPEG, QT and ASF. Also, various additional
  MIME types are detected.
• The Metadata Extraction Tool was
  developed by the National Library of New Zealand to programmatically
  extract preservation metadata from a range of file formats like PDF
  documents, image files, sound files Microsoft office documents, and
  many others.
• TagLib is a library for reading and editing the
  meta-data of several popular audio formats. Currently it supports
  both ID3v1 and ID3v2 for MP3 files, Ogg Vorbis comments and ID3 tags
  and Vorbis comments in FLAC, MPC, Speex, WavPack TrueAudio, WAV,
  AIFF, MP4 and ASF files.