Wed Oct 28 15:47:56 2009

Asterisk developer's documentation


translate.h

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00001 /*
00002  * Asterisk -- An open source telephony toolkit.
00003  *
00004  * Copyright (C) 1999 - 2005, Digium, Inc.
00005  *
00006  * Mark Spencer <markster@digium.com>
00007  *
00008  * See http://www.asterisk.org for more information about
00009  * the Asterisk project. Please do not directly contact
00010  * any of the maintainers of this project for assistance;
00011  * the project provides a web site, mailing lists and IRC
00012  * channels for your use.
00013  *
00014  * This program is free software, distributed under the terms of
00015  * the GNU General Public License Version 2. See the LICENSE file
00016  * at the top of the source tree.
00017  */
00018 
00019 /*! \file
00020  * \brief Translate via the use of pseudo channels
00021  */
00022 
00023 #ifndef _ASTERISK_TRANSLATE_H
00024 #define _ASTERISK_TRANSLATE_H
00025 
00026 #define MAX_FORMAT 32
00027 
00028 #if defined(__cplusplus) || defined(c_plusplus)
00029 extern "C" {
00030 #endif
00031 
00032 #include "asterisk/frame.h"
00033 #include "asterisk/plc.h"
00034 
00035 /* Declared by individual translators */
00036 struct ast_translator_pvt;
00037 
00038 /*! data structure associated with a translator */
00039 struct ast_translator {
00040    /*! Name of translator */
00041    char name[80];
00042    /*! Source format */
00043    int srcfmt;
00044    /*! Destination format */
00045    int dstfmt;
00046    /*! Private data associated with the translator */
00047    struct ast_translator_pvt *(*newpvt)(void);
00048    /*! Input frame callback */
00049    int (*framein)(struct ast_translator_pvt *pvt, struct ast_frame *in);
00050    /*! Output frame callback */
00051    struct ast_frame * (*frameout)(struct ast_translator_pvt *pvt);
00052    /*! Destroy translator callback */
00053    void (*destroy)(struct ast_translator_pvt *pvt);
00054    /* For performance measurements */
00055    /*! Generate an example frame */
00056    struct ast_frame * (*sample)(void);
00057    /*! Cost in milliseconds for encoding/decoding 1 second of sound */
00058    int cost;
00059    /*! For linking, not to be modified by the translator */
00060    struct ast_translator *next;
00061 };
00062 
00063 struct ast_trans_pvt;
00064 
00065 /*! Register a translator */
00066 /*! 
00067  * \param t populated ast_translator structure
00068  * This registers a codec translator with asterisk
00069  * Returns 0 on success, -1 on failure
00070  */
00071 extern int ast_register_translator(struct ast_translator *t);
00072 
00073 /*! Unregister a translator */
00074 /*!
00075  * \param t translator to unregister
00076  * Unregisters the given tranlator
00077  * Returns 0 on success, -1 on failure
00078  */
00079 extern int ast_unregister_translator(struct ast_translator *t);
00080 
00081 /*! Chooses the best translation path */
00082 /*! 
00083  * Given a list of sources, and a designed destination format, which should
00084    I choose? Returns 0 on success, -1 if no path could be found.  Modifies
00085    dests and srcs in place 
00086    */
00087 extern int ast_translator_best_choice(int *dsts, int *srcs);
00088 
00089 /*!Builds a translator path */
00090 /*! 
00091  * \param dest destination format
00092  * \param source source format
00093  * Build a path (possibly NULL) from source to dest 
00094  * Returns ast_trans_pvt on success, NULL on failure
00095  * */
00096 extern struct ast_trans_pvt *ast_translator_build_path(int dest, int source);
00097 
00098 /*! Frees a translator path */
00099 /*!
00100  * \param tr translator path to get rid of
00101  * Frees the given translator path structure
00102  */
00103 extern void ast_translator_free_path(struct ast_trans_pvt *tr);
00104 
00105 /*! translates one or more frames */
00106 /*! 
00107  * \param tr translator structure to use for translation
00108  * \param f frame to translate
00109  * \param consume Whether or not to free the original frame
00110  * Apply an input frame into the translator and receive zero or one output frames.  Consume
00111  * determines whether the original frame should be freed
00112  * Returns an ast_frame of the new translation format on success, NULL on failure
00113  */
00114 extern struct ast_frame *ast_translate(struct ast_trans_pvt *tr, struct ast_frame *f, int consume);
00115 
00116 #if defined(__cplusplus) || defined(c_plusplus)
00117 }
00118 #endif
00119 
00120 #endif /* _ASTERISK_TRANSLATE_H */

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