[mad-user] libid3 documentation

[tj]

Where can I find out how to use libid3tag library?

All I wnat to do is open an mp3 file, see if it has or hasn't a tag. If
it does, get song and artist and el me where the start of mp3 audio is..
If no id3v2, let me know so I know the audio is at the front of the file.

tj

[Rob Leslie]

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Post by tj
Where can I find out how to use libid3tag library?

You can find out how to use the library primarily by examining the
interface header file, id3tag.h, but also by asking questions and
reviewing the existing source code that makes use of the library.

Post by tj
All I wnat to do is open an mp3 file, see if it has or hasn't a tag.
If it does, get song and artist and el me where the start of mp3 audio
is.. If no id3v2, let me know so I know the audio is at the front of
the file.

The id3_tag_query() function may be helpful. If you pass it at least
ID3_TAG_QUERYSIZE bytes of data from the beginning of your file, it
will tell you whether an ID3 tag lives there, and if so, its length.
The start of MP3 audio should therefore (usually) be found after this
length from the beginning of the file.

To parse the tag and get song and artist info, you can either read the
tag data yourself and pass the data block to id3_tag_parse(), or you
can use the id3_file_* interface to read the tag(s) automatically. The
latter interface will check for both v1 and v2 ID3 tags in all their
myriad possible locations (beginning, end, middle of the file) and
properly chain multiple ID3v2 tags, providing a single coherent view of
the relevant tag information.

Post by tj
In trying to learn how to use libid3, since there sems to be no
documentatio. I am looking at soure trying to figure out how to use
it. The first problem is the practically every call uses a pointer to
a "struct id3_file" . Now, the problem is that there is no definition
for id3_file structure in any .h file. I finally found it in file.c, a
source file. How the hell are you supposed to use it in your app when
the prototype is in a package source file?

It's not in any public interface header file because it's not a public
interface. You don't need the structure's definition to receive and
pass around pointers to it; you obtain a pointer by calling
id3_file_open() or id3_file_fdopen().