Wed Aug 18 22:33:56 2010

Asterisk developer's documentation


slinfactory.c

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00001 /*
00002  * Asterisk -- An open source telephony toolkit.
00003  *
00004  * Copyright (C) 2005, Anthony Minessale II.
00005  *
00006  * Anthony Minessale <anthmct@yahoo.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  *
00021  * \brief A machine to gather up arbitrary frames and convert them
00022  * to raw slinear on demand.
00023  *
00024  * \author Anthony Minessale <anthmct@yahoo.com>
00025  */
00026 
00027 #include "asterisk.h"
00028 
00029 ASTERISK_FILE_VERSION(__FILE__, "$Revision: 201096 $")
00030 
00031 #include "asterisk/frame.h"
00032 #include "asterisk/slinfactory.h"
00033 #include "asterisk/translate.h"
00034 
00035 /*!
00036  * \brief Initialize an slinfactory
00037  *
00038  * \arg sf The slinfactory to initialize
00039  *
00040  * \return Nothing
00041  */
00042 void ast_slinfactory_init(struct ast_slinfactory *sf) 
00043 {
00044    memset(sf, 0, sizeof(*sf));
00045    sf->offset = sf->hold;
00046 }
00047 
00048 /*!
00049  * \brief Destroy the contents of a slinfactory
00050  *
00051  * \arg sf The slinfactory that is no longer needed
00052  *
00053  * This function will free any memory allocated for the contents of the
00054  * slinfactory.  It does not free the slinfactory itself.  If the sf is
00055  * malloc'd, then it must be explicitly free'd after calling this function.
00056  *
00057  * \return Nothing
00058  */
00059 void ast_slinfactory_destroy(struct ast_slinfactory *sf) 
00060 {
00061    struct ast_frame *f;
00062 
00063    if (sf->trans) {
00064       ast_translator_free_path(sf->trans);
00065       sf->trans = NULL;
00066    }
00067 
00068    while ((f = AST_LIST_REMOVE_HEAD(&sf->queue, frame_list)))
00069       ast_frfree(f);
00070 }
00071 
00072 /*!
00073  * \brief Feed audio into an slinfactory
00074  *
00075  * \arg sf The slinfactory to feed into
00076  * \arg f Frame containing audio to feed in
00077  *
00078  * \return Number of frames currently in factory
00079  */
00080 int ast_slinfactory_feed(struct ast_slinfactory *sf, struct ast_frame *f)
00081 {
00082    struct ast_frame *begin_frame = f, *duped_frame = NULL, *frame_ptr;
00083    unsigned int x = 0;
00084 
00085    /* In some cases, we can be passed a frame which has no data in it, but
00086     * which has a positive number of samples defined. Once such situation is
00087     * when a jitter buffer is in use and the jitter buffer interpolates a frame.
00088     * The frame it produces has data set to NULL, datalen set to 0, and samples
00089     * set to either 160 or 240.
00090     */
00091    if (!f->data.ptr) {
00092       return 0;
00093    }
00094 
00095    if (f->subclass != AST_FORMAT_SLINEAR && f->subclass != AST_FORMAT_SLINEAR16) {
00096       if (sf->trans && f->subclass != sf->format) {
00097          ast_translator_free_path(sf->trans);
00098          sf->trans = NULL;
00099       }
00100 
00101       if (!sf->trans) {
00102          if (!(sf->trans = ast_translator_build_path((f->subclass == AST_FORMAT_G722 ? AST_FORMAT_SLINEAR16 : AST_FORMAT_SLINEAR), f->subclass))) {
00103             ast_log(LOG_WARNING, "Cannot build a path from %s to slin\n", ast_getformatname(f->subclass));
00104             return 0;
00105          }
00106          sf->format = f->subclass;
00107       }
00108 
00109       if (!(begin_frame = ast_translate(sf->trans, f, 0))) {
00110          return 0;
00111       }
00112       
00113       if (!(duped_frame = ast_frisolate(begin_frame))) {
00114          return 0;
00115       }
00116 
00117       if (duped_frame != begin_frame) {
00118          ast_frfree(begin_frame);
00119       }
00120    } else {
00121       if (sf->trans) {
00122          ast_translator_free_path(sf->trans);
00123          sf->trans = NULL;
00124       }
00125       if (!(duped_frame = ast_frdup(f)))
00126          return 0;
00127    }
00128 
00129    AST_LIST_TRAVERSE(&sf->queue, frame_ptr, frame_list)
00130       x++;
00131 
00132    /* if the frame was translated, the translator may have returned multiple
00133       frames, so process each of them
00134    */
00135    for (begin_frame = duped_frame; begin_frame; begin_frame = AST_LIST_NEXT(begin_frame, frame_list)) {
00136       AST_LIST_INSERT_TAIL(&sf->queue, begin_frame, frame_list);
00137       sf->size += begin_frame->samples;
00138    }
00139 
00140    return x;
00141 }
00142 
00143 /*!
00144  * \brief Read samples from an slinfactory
00145  *
00146  * \arg sf The slinfactory to read from
00147  * \arg buf Buffer to put samples into
00148  * \arg samples Number of samples wanted
00149  *
00150  * \return Number of samples read
00151  */
00152 int ast_slinfactory_read(struct ast_slinfactory *sf, short *buf, size_t samples) 
00153 {
00154    struct ast_frame *frame_ptr;
00155    unsigned int sofar = 0, ineed, remain;
00156    short *frame_data, *offset = buf;
00157 
00158    while (sofar < samples) {
00159       ineed = samples - sofar;
00160 
00161       if (sf->holdlen) {
00162          if (sf->holdlen <= ineed) {
00163             memcpy(offset, sf->hold, sf->holdlen * sizeof(*offset));
00164             sofar += sf->holdlen;
00165             offset += sf->holdlen;
00166             sf->holdlen = 0;
00167             sf->offset = sf->hold;
00168          } else {
00169             remain = sf->holdlen - ineed;
00170             memcpy(offset, sf->offset, ineed * sizeof(*offset));
00171             sofar += ineed;
00172             sf->offset += ineed;
00173             sf->holdlen = remain;
00174          }
00175          continue;
00176       }
00177       
00178       if ((frame_ptr = AST_LIST_REMOVE_HEAD(&sf->queue, frame_list))) {
00179          frame_data = frame_ptr->data.ptr;
00180          
00181          if (frame_ptr->samples <= ineed) {
00182             memcpy(offset, frame_data, frame_ptr->samples * sizeof(*offset));
00183             sofar += frame_ptr->samples;
00184             offset += frame_ptr->samples;
00185          } else {
00186             remain = frame_ptr->samples - ineed;
00187             memcpy(offset, frame_data, ineed * sizeof(*offset));
00188             sofar += ineed;
00189             frame_data += ineed;
00190             if (remain > (AST_SLINFACTORY_MAX_HOLD - sf->holdlen)) {
00191                remain = AST_SLINFACTORY_MAX_HOLD - sf->holdlen;
00192             }
00193             memcpy(sf->hold, frame_data, remain * sizeof(*offset));
00194             sf->holdlen = remain;
00195          }
00196          ast_frfree(frame_ptr);
00197       } else {
00198          break;
00199       }
00200    }
00201 
00202    sf->size -= sofar;
00203    return sofar;
00204 }
00205 
00206 /*!
00207  * \brief Retrieve number of samples currently in an slinfactory
00208  *
00209  * \arg sf The slinfactory to peek into
00210  *
00211  * \return Number of samples in slinfactory
00212  */
00213 unsigned int ast_slinfactory_available(const struct ast_slinfactory *sf)
00214 {
00215    return sf->size;
00216 }
00217 
00218 /*!
00219  * \brief Flush the contents of an slinfactory
00220  *
00221  * \arg sf The slinfactory to flush
00222  *
00223  * \return Nothing
00224  */
00225 void ast_slinfactory_flush(struct ast_slinfactory *sf)
00226 {
00227    struct ast_frame *fr = NULL;
00228 
00229    if (sf->trans) {
00230       ast_translator_free_path(sf->trans);
00231       sf->trans = NULL;
00232    }
00233 
00234    while ((fr = AST_LIST_REMOVE_HEAD(&sf->queue, frame_list)))
00235       ast_frfree(fr);
00236 
00237    sf->size = sf->holdlen = 0;
00238    sf->offset = sf->hold;
00239 
00240    return;
00241 }

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