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 */