translate.h

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2006, Digium, Inc.
 *
 * Mark Spencer <markster@digium.com>
 *
 * 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 Support for translation of data formats.
 * \ref translate.c
 */

#ifndef _ASTERISK_TRANSLATE_H
#define _ASTERISK_TRANSLATE_H

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

#if 1 /* need lots of stuff... */
#include "asterisk/frame.h"
#include "asterisk/plc.h"
#include "asterisk/linkedlists.h"
#endif

struct ast_trans_pvt;   /* declared below */

/*!
 * \brief Translator Cost Table definition.
 *
 * \note The defined values in this table must be used to set
 * the translator's table_cost value.
 *
 * \note The cost value of the first two values must always add
 * up to be greater than the largest value defined in this table.
 * This is done to guarantee a direct translation will always
 * have precedence over a multi step translation.
 *
 * \details This table is built in a way that allows translation
 * paths to be built that guarantee the best possible balance
 * between performance and quality.  With this table direct
 * translation paths between two formats will always take precedence
 * over multi step paths, lossless intermediate steps will always
 * be chosen over lossy intermediate steps, and preservation of
 * sample rate across the translation will always have precedence
 * over a path that involves any re-sampling.
 */
enum ast_trans_cost_table {

   /* Lossless Source Translation Costs */

   /*! [lossless -> lossless] original sampling */
   AST_TRANS_COST_LL_LL_ORIGSAMP = 400000,
   /*! [lossless -> lossy]    original sampling */
   AST_TRANS_COST_LL_LY_ORIGSAMP = 600000,

   /*! [lossless -> lossless] up sample */
   AST_TRANS_COST_LL_LL_UPSAMP   = 800000,
   /*! [lossless -> lossy]    up sample */
   AST_TRANS_COST_LL_LY_UPSAMP   = 825000,

   /*! [lossless -> lossless] down sample */
   AST_TRANS_COST_LL_LL_DOWNSAMP = 850000,
   /*! [lossless -> lossy]    down sample */
   AST_TRANS_COST_LL_LY_DOWNSAMP = 875000,

   /*! [lossless -> unknown]    unknown.
    * This value is for a lossless source translation
    * with an unknown destination and or sample rate conversion. */
   AST_TRANS_COST_LL_UNKNOWN     = 885000,

   /* Lossy Source Translation Costs */

   /*! [lossy -> lossless]    original sampling */
   AST_TRANS_COST_LY_LL_ORIGSAMP = 900000,
   /*! [lossy -> lossy]       original sampling */
   AST_TRANS_COST_LY_LY_ORIGSAMP = 915000,

   /*! [lossy -> lossless]    up sample */
   AST_TRANS_COST_LY_LL_UPSAMP   = 930000,
   /*! [lossy -> lossy]       up sample */
   AST_TRANS_COST_LY_LY_UPSAMP   = 945000,

   /*! [lossy -> lossless]    down sample */
   AST_TRANS_COST_LY_LL_DOWNSAMP = 960000,
   /*! [lossy -> lossy]       down sample */
   AST_TRANS_COST_LY_LY_DOWNSAMP = 975000,

   /*! [lossy -> unknown]    unknown.
    * This value is for a lossy source translation
    * with an unknown destination and or sample rate conversion. */
   AST_TRANS_COST_LY_UNKNOWN     = 985000,

};

/*! \brief
 * Descriptor of a translator. 
 *
 * Name, callbacks, and various options
 * related to run-time operation (size of buffers, auxiliary
 * descriptors, etc).
 *
 * A codec registers itself by filling the relevant fields
 * of a structure and passing it as an argument to
 * ast_register_translator(). The structure should not be
 * modified after a successful registration, and its address
 * must be used as an argument to ast_unregister_translator().
 *
 * As a minimum, a translator should supply name, srcfmt and dstfmt,
 * the required buf_size (in bytes) and buffer_samples (in samples),
 * and a few callbacks (framein, frameout, sample).
 * The outbuf is automatically prepended by AST_FRIENDLY_OFFSET
 * spare bytes so generic routines can place data in there.
 *
 * Note, the translator is not supposed to do any memory allocation
 * or deallocation, nor any locking, because all of this is done in
 * the generic code.
 *
 * Translators using generic plc (packet loss concealment) should
 * supply a non-zero plc_samples indicating the size (in samples)
 * of artificially generated frames and incoming data.
 * Generic plc is only available for dstfmt = SLINEAR
 */
struct ast_translator {
   char name[80];                         /*!< Name of translator */
   struct ast_format src_format;          /*!< Source format */
   struct ast_format dst_format;          /*!< Destination format */

   int table_cost;                        /*!< Cost value associated with this translator based
                                           *   on translation cost table. */
   int comp_cost;                         /*!< Cost value associated with this translator based
                                           *   on computation time. This cost value is computed based
                                 *   on the time required to translate sample data. */

   int (*newpvt)(struct ast_trans_pvt *); /*!< initialize private data 
                                            *   associated with the translator */

   int (*framein)(struct ast_trans_pvt *pvt, struct ast_frame *in);
                                          /*!< Input frame callback. Store 
                                           *   (and possibly convert) input frame. */

   struct ast_frame * (*frameout)(struct ast_trans_pvt *pvt);
                                          /*!< Output frame callback. Generate a frame 
                                           *   with outbuf content. */

   void (*destroy)(struct ast_trans_pvt *pvt);
                                          /*!< cleanup private data, if needed 
                                           *   (often unnecessary). */

   struct ast_frame * (*sample)(void);    /*!< Generate an example frame */

   /*!\brief size of outbuf, in samples. Leave it 0 if you want the framein
    * callback deal with the frame. Set it appropriately if you
    * want the code to checks if the incoming frame fits the
    * outbuf (this is e.g. required for plc).
    */
   int buffer_samples;                    /*< size of outbuf, in samples */

   /*! \brief size of outbuf, in bytes. Mandatory. The wrapper code will also
    * allocate an AST_FRIENDLY_OFFSET space before.
    */
   int buf_size;

   int desc_size;                         /*!< size of private descriptor in pvt->pvt, if any */
   int native_plc;                        /*!< true if the translator can do native plc */

   struct ast_module *module;             /*!< opaque reference to the parent module */

   int active;                            /*!< Whether this translator should be used or not */
   int src_fmt_index;                     /*!< index of the source format in the matrix table */
   int dst_fmt_index;                     /*!< index of the destination format in the matrix table */
   AST_LIST_ENTRY(ast_translator) list;   /*!< link field */
};

/*! \brief
 * Default structure for translators, with the basic fields and buffers,
 * all allocated as part of the same chunk of memory. The buffer is
 * preceded by \ref AST_FRIENDLY_OFFSET bytes in front of the user portion.
 * 'buf' points right after this space.
 *
 * *_framein() routines operate in two ways:
 * 1. some convert on the fly and place the data directly in outbuf;
 *    in this case 'samples' and 'datalen' contain the number of samples
 *    and number of bytes available in the buffer.
 *    In this case we can use a generic *_frameout() routine that simply
 *    takes whatever is there and places it into the output frame.
 * 2. others simply store the (unconverted) samples into a working
 *    buffer, and leave the conversion task to *_frameout().
 *    In this case, the intermediate buffer must be in the private
 *    descriptor, 'datalen' is left to 0, while 'samples' is still
 *    updated with the number of samples received.
 */
struct ast_trans_pvt {
   struct ast_translator *t;
   struct ast_frame f;         /*!< used in frameout */
   /*! If a translation path using a format with attributes requires the output
    * to be a specific set of attributes, this variable will be set describing those
    * attributes to the translator.  Otherwise, the translator must choose a set
    * of format attributes for the destination that preserves the quality of the
    * audio in the best way possible. */
   struct ast_format explicit_dst;
   int samples;                /*!< samples available in outbuf */
   /*! \brief actual space used in outbuf */
   int datalen;
   void *pvt;                  /*!< more private data, if any */
   union {
      char *c;                /*!< the useful portion of the buffer */
      unsigned char *uc;      /*!< the useful portion of the buffer */
      int16_t *i16;
      uint8_t *ui8;
   } outbuf;
   plc_state_t *plc;           /*!< optional plc pointer */
   struct ast_trans_pvt *next; /*!< next in translator chain */
   struct timeval nextin;
   struct timeval nextout;
};

/*! \brief generic frameout function */
struct ast_frame *ast_trans_frameout(struct ast_trans_pvt *pvt,
        int datalen, int samples);

struct ast_trans_pvt;

/*!
 * \brief Register a translator
 * This registers a codec translator with asterisk
 * \param t populated ast_translator structure
 * \param module handle to the module that owns this translator
 * \return 0 on success, -1 on failure
 */
int __ast_register_translator(struct ast_translator *t, struct ast_module *module);

/*! \brief See \ref __ast_register_translator() */
#define ast_register_translator(t) __ast_register_translator(t, ast_module_info->self)

/*!
 * \brief Unregister a translator
 * Unregisters the given tranlator
 * \param t translator to unregister
 * \return 0 on success, -1 on failure
 */
int ast_unregister_translator(struct ast_translator *t);

/*!
 * \brief Activate a previously deactivated translator
 * \param t translator to activate
 * \return nothing
 *
 * Enables the specified translator for use.
 */
void ast_translator_activate(struct ast_translator *t);

/*!
 * \brief Deactivate a translator
 * \param t translator to deactivate
 * \return nothing
 *
 * Disables the specified translator from being used.
 */
void ast_translator_deactivate(struct ast_translator *t);

/*!
 * \brief Chooses the best translation path
 *
 * Given a list of sources, and a designed destination format, which should
 * I choose?
 *
 * \param destination capabilities
 * \param source capabilities
 * \param destination format chosen out of destination capabilities
 * \param source format chosen out of source capabilities
 * \return Returns 0 on success, -1 if no path could be found.
 *
 * \note dst_cap and src_cap are not mondified.
 */
int ast_translator_best_choice(struct ast_format_cap *dst_cap,
   struct ast_format_cap *src_cap,
   struct ast_format *dst_fmt_out,
   struct ast_format *src_fmt_out);

/*! 
 * \brief Builds a translator path
 * Build a path (possibly NULL) from source to dest 
 * \param dest destination format
 * \param source source format
 * \return ast_trans_pvt on success, NULL on failure
 * */
struct ast_trans_pvt *ast_translator_build_path(struct ast_format *dest, struct ast_format *source);

/*!
 * \brief Frees a translator path
 * Frees the given translator path structure
 * \param tr translator path to get rid of
 */
void ast_translator_free_path(struct ast_trans_pvt *tr);

/*!
 * \brief translates one or more frames
 * Apply an input frame into the translator and receive zero or one output frames.  Consume
 * determines whether the original frame should be freed
 * \param tr translator structure to use for translation
 * \param f frame to translate
 * \param consume Whether or not to free the original frame
 * \return an ast_frame of the new translation format on success, NULL on failure
 */
struct ast_frame *ast_translate(struct ast_trans_pvt *tr, struct ast_frame *f, int consume);

/*!
 * \brief Returns the number of steps required to convert from 'src' to 'dest'.
 * \param dest destination format
 * \param src source format
 * \return the number of translation steps required, or -1 if no path is available
 */
unsigned int ast_translate_path_steps(struct ast_format *dest, struct ast_format *src);

/*!
 * \brief Find available formats
 * \param dest possible destination formats
 * \param src source formats
 * \param result capabilities structure to store available formats in
 *
 * \return the destination formats that are available in the source or translatable
 *
 * The result will include all formats from 'dest' that are either present
 * in 'src' or translatable from a format present in 'src'.
 *
 * \note Only a single audio format and a single video format can be
 * present in 'src', or the function will produce unexpected results.
 */
void ast_translate_available_formats(struct ast_format_cap *dest, struct ast_format_cap *src, struct ast_format_cap *result);

/*!
 * \brief Puts a string representation of the translation path into outbuf
 * \param translator structure containing the translation path
 * \param ast_str output buffer
 * \retval on success pointer to beginning of outbuf. on failure "".
 */
const char *ast_translate_path_to_str(struct ast_trans_pvt *t, struct ast_str **str);

/*!
 * \brief Initialize the translation matrix and index to format conversion table.
 * \retval 0 on success
 * \retval -1 on failure
 */
int ast_translate_init(void);

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

#endif /* _ASTERISK_TRANSLATE_H */