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ezstream/src/metadata.h
2015-02-23 13:51:55 +01:00

115 lines
3.9 KiB
C

/*
* Copyright (c) 2007 Moritz Grimm <mgrimm@mrsserver.net>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#ifndef __METADATA_H__
#define __METADATA_H__
#define METADATA_MAX 1023
enum metadata_request {
METADATA_ALL = 0,
METADATA_STRING,
METADATA_ARTIST,
METADATA_TITLE
};
typedef struct metadata metadata_t;
/*
* Read the metadata of a media file and return a new metadata handle on
* success, or NULL on failure. The returned handle is "branded" for reading
* metadata from media files.
*/
metadata_t * metadata_file(const char * /* filename */,
int /* normalize strings */);
/*
* Create a metadata handle that is "branded" for acquiring metadata from an
* external program. The handle is returned on success, or NULL on failure.
* The program is NOT YET being queried, use metadata_program_update() for
* that. Also, the program (or script) needs to follow these rules:
*
* - Print one line to standard output and exit.
* - Accept no command line parameter and return a complete metadata string
* (for metadata_get_string()). The program *should* always return
* something in this case (e.g. something based on the filename in case no
* metadata is available.)
* - Accept the command line parameter "artist" and return only the artist
* metadata, or an empty string if no artist information is available.
* - Accept the command line parameter "title" and return only the song title
* metadata, or an empty string if no artist information is available.
* - Return at most METADATA_MAX characters, or the result will be truncated.
*/
metadata_t * metadata_program(const char * /* program name */,
int /* normalize strings */);
/*
* Free all memory used by a metadata handle that has been created with
* metadata_file() or metadata_program().
*/
void metadata_free(metadata_t **);
/*
* Update/read the metadata for the given handle. Returns 1 on success, and 0
* on failure.
*/
int metadata_file_update(metadata_t *);
/*
* Update/read the specified metadata for the given program-handle. Returns 1
* on success, and 0 on failure.
*/
int metadata_program_update(metadata_t *, enum metadata_request);
/*
* Returns a pointer to a metadata string ``artist - title'', or just
* ``artist'' or ``title'' if one of the two is not available. If neither
* are present, it returns the filename without the extension. An empty string
* is returned for metadata_program() handles that didn't supply any generic
* information.
*/
const char * metadata_get_string(metadata_t *);
/*
* Returns a pointer to the artist string, which may be empty.
*/
const char * metadata_get_artist(metadata_t *);
/*
* Returns a pointer to the title string, which may be empty.
*/
const char * metadata_get_title(metadata_t *);
/*
* Returns a pointer to the filename used in the metadata handle.
*/
const char * metadata_get_filename(metadata_t *);
/*
* Returns the length of the song, in seconds, or -1 if the information is not
* available.
*/
int metadata_get_length(metadata_t *);
/*
* Allocates and returns a meaningful string based on a metadata handle's
* content. The result is what metadata_get_string() defaults to if an external
* program is not used.
*/
char * metadata_assemble_string(metadata_t *);
#endif /* __METADATA_H__ */