mod_format.h

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2006, Digium, Inc.
 *
 * Mark Spencer <[email protected]>
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */

/*! \file
 * \brief Header for providers of file and format handling routines.
 * Clients of these routines should include "asterisk/file.h" instead.
 */

#ifndef _ASTERISK_MOD_FORMAT_H
#define _ASTERISK_MOD_FORMAT_H

#include "asterisk/file.h"
#include "asterisk/frame.h"

#if defined(__cplusplus) || defined(c_plusplus)
extern "C" {
#endif

/*! \brief
 * Each supported file format is described by the following structure.
 *
 * Not all are necessary, the support routine implement default
 * values for some of them.
 * A handler typically fills a structure initializing the desired
 * fields, and then calls ast_format_def_register() with the (readonly)
 * structure as an argument.
 */
struct ast_format_def {
 char name[80]; /*!< Name of format */
 char exts[80]; /*!< Extensions (separated by | if more than one)
 * this format can read. First is assumed for writing (e.g. .mp3) */
 char mime_types[80]; /*!< MIME Types related to the format (separated by | if more than one)*/
 struct ast_format *format; /*!< Format of frames it uses/provides (one only) */
 /*!
 * \brief Prepare an input stream for playback.
 * \return 0 on success, -1 on error.
 * The FILE is already open (in s->f) so this function only needs to perform
 * any applicable validity checks on the file. If none is required, the
 * function can be omitted.
 */
 int (*open)(struct ast_filestream *s);
 /*!
 * \brief Prepare a stream for output, and comment it appropriately if applicable.
 * \return 0 on success, -1 on error.
 * Same as the open, the FILE is already open so the function just needs to
 * prepare any header and other fields, if any.
 * The function can be omitted if nothing is needed.
 */
 int (*rewrite)(struct ast_filestream *s, const char *comment);
 /*! Write a frame to a channel */
 int (*write)(struct ast_filestream *, struct ast_frame *);
 /*! seek num samples into file, whence - like a normal seek but with offset in samples */
 int (*seek)(struct ast_filestream *, off_t, int);
 int (*trunc)(struct ast_filestream *fs); /*!< trunc file to current position */
 off_t (*tell)(struct ast_filestream *fs); /*!< tell current position */
 /*! Read the next frame from the filestream (if available) and report
 * when to get next frame (in samples)
 */
 struct ast_frame * (*read)(struct ast_filestream *, int *whennext);
 /*! Do any closing actions, if any. The descriptor and structure are closed
 * and destroyed by the generic routines, so they must not be done here. */
 void (*close)(struct ast_filestream *);
 char * (*getcomment)(struct ast_filestream *); /*!< Retrieve file comment */

 AST_LIST_ENTRY(ast_format_def) list; /*!< Link */

 /*!
 * If the handler needs a buffer (for read, typically)
 * and/or a private descriptor, put here the
 * required size (in bytes) and the support routine will allocate them
 * for you, pointed by s->buf and s->private, respectively.
 * When allocating a buffer, remember to leave AST_FRIENDLY_OFFSET
 * spare bytes at the bginning.
 */
 int buf_size; /*!< size of frame buffer, if any, aligned to 8 bytes. */
 int desc_size; /*!< size of private descriptor, if any */

 struct ast_module *module;
};

/*! \brief
 * This structure is allocated by file.c in one chunk,
 * together with buf_size and desc_size bytes of memory
 * to be used for private purposes (e.g. buffers etc.)
 */
struct ast_filestream {
 /*! Everybody reserves a block of AST_RESERVED_POINTERS pointers for us */
 struct ast_format_def *fmt; /* need to write to the lock and usecnt */
 int flags;
 mode_t mode;
 char *open_filename;
 char *filename;
 char *realfilename;
 /*! Video file stream */
 struct ast_filestream *vfs;
 /*! Transparently translate from another format -- just once */
 struct ast_trans_pvt *trans;
 struct ast_tranlator_pvt *tr;
 struct ast_format *lastwriteformat;
 int lasttimeout;
 struct ast_channel *owner;
 FILE *f;
 /*!
 * \brief frame produced by read, typically
 * \note This frame holds a fr.subclass.format ref.
 */
 struct ast_frame fr;
 char *buf; /*!< buffer pointed to by ast_frame; */
 void *_private; /*!< pointer to private buffer */
 const char *orig_chan_name;
 char *write_buffer;
};

/*!
 * \brief Register a new file format capability.
 * Adds a format to Asterisk's format abilities.
 * \retval 0 on success
 * \retval -1 on failure
 */
int __ast_format_def_register(const struct ast_format_def *f, struct ast_module *mod);
#define ast_format_def_register(f) __ast_format_def_register(f, AST_MODULE_SELF)

/*!
 * \brief Unregisters a file format
 * \param name the name of the format you wish to unregister
 * Unregisters a format based on the name of the format.
 * \retval 0 on success
 * \retval -1 on failure to unregister
 */
int ast_format_def_unregister(const char *name);

#if defined(__cplusplus) || defined(c_plusplus)
}
#endif

#endif /* _ASTERISK_MOD_FORMAT_H */