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201 lines
6.9 KiB
201 lines
6.9 KiB
/*
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* Asterisk -- An open source telephony toolkit.
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*
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* Copyright (C) 1999 - 2005, Digium, Inc.
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*
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* Mark Spencer <markster@digium.com>
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*
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* See http://www.asterisk.org for more information about
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* the Asterisk project. Please do not directly contact
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* any of the maintainers of this project for assistance;
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* the project provides a web site, mailing lists and IRC
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* channels for your use.
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*
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* This program is free software, distributed under the terms of
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* the GNU General Public License Version 2. See the LICENSE file
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* at the top of the source tree.
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*/
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/*! \file
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* \brief Support for translation of data formats.
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*/
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#ifndef _ASTERISK_TRANSLATE_H
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#define _ASTERISK_TRANSLATE_H
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#define MAX_FORMAT 32
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#if defined(__cplusplus) || defined(c_plusplus)
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extern "C" {
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#endif
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#if 1 /* need lots of stuff... */
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#include "asterisk/frame.h"
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#include "asterisk/plc.h"
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#include "asterisk/linkedlists.h"
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#include "asterisk/module.h"
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#endif
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struct ast_trans_pvt; /* declared below */
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/*!
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* Descriptor of a translator. Name, callbacks, and various options
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* related to run-time operation (size of buffers, auxiliary
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* descriptors, etc).
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* A coded registers itself by filling the relevant fields
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* of a structure and passing it as an argument to
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* ast_register_translator(). The structure should not be
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* modified after a successful register(), and its address
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* must be used as an argument to ast_unregister_translator().
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*
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* As a minimum, a translator should supply name, srcfmt and dstfmt,
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* the required buf_size (in bytes) and buffer_samples (in samples),
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* and a few callbacks (framein, frameout, sample).
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* The outbuf is automatically prepended by AST_FRIENDLY_OFFSET
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* spare bytes so generic routines can place data in there.
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*
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* Note, the translator is not supposed to do any memory allocation
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* or deallocation, nor any locking, because all of this is done in
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* the generic code.
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*
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* Translators using generic plc (packet loss concealment) should
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* supply a non-zero plc_samples indicating the size (in samples)
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* of artificially generated frames and incoming data.
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* Generic plc is only available for dstfmt = SLINEAR
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*/
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struct ast_translator {
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const char name[80]; /*! Name of translator */
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int srcfmt; /*! Source format (note: bit position) */
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int dstfmt; /*! Destination format (note: bit position) */
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/*! initialize private data associated with the translator */
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void *(*newpvt)(struct ast_trans_pvt *);
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/*! Input frame callback. Store (and possibly convert) input frame. */
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int (*framein)(struct ast_trans_pvt *pvt, struct ast_frame *in);
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/*! Output frame callback. Generate a frame with outbuf content. */
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struct ast_frame * (*frameout)(struct ast_trans_pvt *pvt);
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/*! cleanup private data, if needed (often unnecessary). */
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void (*destroy)(struct ast_trans_pvt *pvt);
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struct ast_frame * (*sample)(void); /*! Generate an example frame */
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/*! size of outbuf, in samples. Leave it 0 if you want the framein
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* callback deal with the frame. Set it appropriately if you
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* want the code to checks if the incoming frame fits the
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* outbuf (this is e.g. required for plc).
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*/
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int buffer_samples; /* size of outbuf, in samples */
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/*! size of outbuf, in bytes. Mandatory. The wrapper code will also
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* allocate an AST_FRIENDLY_OFFSET space before.
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*/
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int buf_size;
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int desc_size; /*! size of private descriptor in pvt->pvt, if any */
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int plc_samples; /* set to the plc block size if used, 0 otherwise */
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int useplc; /* current status of plc, changed at runtime */
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struct ast_module_lock *lockp;
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int cost; /*! Cost in milliseconds for encoding/decoding 1 second of sound */
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AST_LIST_ENTRY(ast_translator) list; /*! link field */
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};
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/*
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* Default structure for translators, with the basic fields and buffers,
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* all allocated as part of the same chunk of memory. The buffer is
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* preceded by AST_FRIENDLY_OFFSET bytes in front of the user portion.
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* 'buf' points right after this space.
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*
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* *_framein() routines operate in two ways:
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* 1. some convert on the fly and place the data directly in outbuf;
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* in this case 'samples' and 'datalen' contain the number of samples
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* and number of bytes available in the buffer.
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* In this case we can use a generic *_frameout() routine that simply
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* takes whatever is there and places it into the output frame.
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* 2. others simply store the (unconverted) samples into a working
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* buffer, and leave the conversion task to *_frameout().
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* In this case, the intermediate buffer must be in the private
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* descriptor, 'datalen' is left to 0, while 'samples' is still
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* updated with the number of samples received.
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*/
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struct ast_trans_pvt {
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struct ast_translator *t;
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struct ast_frame f; /* used in frameout */
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int samples; /* samples available in outbuf */
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int datalen; /* actual space used in outbuf */
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void *pvt; /* more private data, if any */
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char *outbuf; /* the useful portion of the buffer */
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plc_state_t *plc; /* optional plc pointer */
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struct ast_trans_pvt *next; /* next in translator chain */
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struct timeval nextin;
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struct timeval nextout;
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};
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/* generic frameout function */
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struct ast_frame *ast_trans_frameout(struct ast_trans_pvt *pvt,
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int datalen, int samples);
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struct ast_trans_pvt;
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/*!
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* \brief Register a translator
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* \param t populated ast_translator structure
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* This registers a codec translator with asterisk
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* Returns 0 on success, -1 on failure
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*/
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int ast_register_translator(struct ast_translator *t);
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/*!
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* \brief Unregister a translator
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* \param t translator to unregister
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* Unregisters the given tranlator
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* Returns 0 on success, -1 on failure
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*/
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int ast_unregister_translator(struct ast_translator *t);
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/*!
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* \brief Chooses the best translation path
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*
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* Given a list of sources, and a designed destination format, which should
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* I choose? Returns 0 on success, -1 if no path could be found. Modifies
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* dests and srcs in place
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*/
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int ast_translator_best_choice(int *dsts, int *srcs);
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/*!
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* \brief Builds a translator path
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* \param dest destination format
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* \param source source format
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* Build a path (possibly NULL) from source to dest
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* Returns ast_trans_pvt on success, NULL on failure
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* */
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struct ast_trans_pvt *ast_translator_build_path(int dest, int source);
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/*!
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* \brief Frees a translator path
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* \param tr translator path to get rid of
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* Frees the given translator path structure
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*/
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void ast_translator_free_path(struct ast_trans_pvt *tr);
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/*!
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* \brief translates one or more frames
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* \param tr translator structure to use for translation
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* \param f frame to translate
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* \param consume Whether or not to free the original frame
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* Apply an input frame into the translator and receive zero or one output frames. Consume
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* determines whether the original frame should be freed
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* Returns an ast_frame of the new translation format on success, NULL on failure
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*/
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struct ast_frame *ast_translate(struct ast_trans_pvt *tr, struct ast_frame *f, int consume);
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#if defined(__cplusplus) || defined(c_plusplus)
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}
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#endif
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#endif /* _ASTERISK_TRANSLATE_H */
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