Thu Apr 28 2011 17:15:25

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: 201097 $")
00030 
00031 #include "asterisk/frame.h"
00032 #include "asterisk/slinfactory.h"
00033 #include "asterisk/translate.h"
00034 
00035 void ast_slinfactory_init(struct ast_slinfactory *sf) 
00036 {
00037    memset(sf, 0, sizeof(*sf));
00038    sf->offset = sf->hold;
00039    sf->output_format = AST_FORMAT_SLINEAR;
00040 }
00041 
00042 int ast_slinfactory_init_rate(struct ast_slinfactory *sf, unsigned int sample_rate) 
00043 {
00044    memset(sf, 0, sizeof(*sf));
00045    sf->offset = sf->hold;
00046    switch (sample_rate) {
00047    case 8000:
00048       sf->output_format = AST_FORMAT_SLINEAR;
00049       break;
00050    case 16000:
00051       sf->output_format = AST_FORMAT_SLINEAR16;
00052       break;
00053    default:
00054       return -1;
00055    }
00056 
00057    return 0;
00058 }
00059 
00060 void ast_slinfactory_destroy(struct ast_slinfactory *sf) 
00061 {
00062    struct ast_frame *f;
00063 
00064    if (sf->trans) {
00065       ast_translator_free_path(sf->trans);
00066       sf->trans = NULL;
00067    }
00068 
00069    while ((f = AST_LIST_REMOVE_HEAD(&sf->queue, frame_list)))
00070       ast_frfree(f);
00071 }
00072 
00073 int ast_slinfactory_feed(struct ast_slinfactory *sf, struct ast_frame *f)
00074 {
00075    struct ast_frame *begin_frame = f, *duped_frame = NULL, *frame_ptr;
00076    unsigned int x = 0;
00077 
00078    /* In some cases, we can be passed a frame which has no data in it, but
00079     * which has a positive number of samples defined. Once such situation is
00080     * when a jitter buffer is in use and the jitter buffer interpolates a frame.
00081     * The frame it produces has data set to NULL, datalen set to 0, and samples
00082     * set to either 160 or 240.
00083     */
00084    if (!f->data.ptr) {
00085       return 0;
00086    }
00087 
00088    if (f->subclass != sf->output_format) {
00089       if (sf->trans && f->subclass != sf->format) {
00090          ast_translator_free_path(sf->trans);
00091          sf->trans = NULL;
00092       }
00093 
00094       if (!sf->trans) {
00095          if (!(sf->trans = ast_translator_build_path(sf->output_format, f->subclass))) {
00096             ast_log(LOG_WARNING, "Cannot build a path from %s to %s\n", ast_getformatname(f->subclass),
00097                ast_getformatname(sf->output_format));
00098             return 0;
00099          }
00100          sf->format = f->subclass;
00101       }
00102 
00103       if (!(begin_frame = ast_translate(sf->trans, f, 0))) {
00104          return 0;
00105       }
00106       
00107       if (!(duped_frame = ast_frisolate(begin_frame))) {
00108          return 0;
00109       }
00110 
00111       if (duped_frame != begin_frame) {
00112          ast_frfree(begin_frame);
00113       }
00114    } else {
00115       if (sf->trans) {
00116          ast_translator_free_path(sf->trans);
00117          sf->trans = NULL;
00118       }
00119       if (!(duped_frame = ast_frdup(f)))
00120          return 0;
00121    }
00122 
00123    AST_LIST_TRAVERSE(&sf->queue, frame_ptr, frame_list) {
00124       x++;
00125    }
00126 
00127    /* if the frame was translated, the translator may have returned multiple
00128       frames, so process each of them
00129    */
00130    for (begin_frame = duped_frame; begin_frame; begin_frame = AST_LIST_NEXT(begin_frame, frame_list)) {
00131       AST_LIST_INSERT_TAIL(&sf->queue, begin_frame, frame_list);
00132       sf->size += begin_frame->samples;
00133    }
00134 
00135    return x;
00136 }
00137 
00138 int ast_slinfactory_read(struct ast_slinfactory *sf, short *buf, size_t samples) 
00139 {
00140    struct ast_frame *frame_ptr;
00141    unsigned int sofar = 0, ineed, remain;
00142    short *frame_data, *offset = buf;
00143 
00144    while (sofar < samples) {
00145       ineed = samples - sofar;
00146 
00147       if (sf->holdlen) {
00148          if (sf->holdlen <= ineed) {
00149             memcpy(offset, sf->hold, sf->holdlen * sizeof(*offset));
00150             sofar += sf->holdlen;
00151             offset += sf->holdlen;
00152             sf->holdlen = 0;
00153             sf->offset = sf->hold;
00154          } else {
00155             remain = sf->holdlen - ineed;
00156             memcpy(offset, sf->offset, ineed * sizeof(*offset));
00157             sofar += ineed;
00158             sf->offset += ineed;
00159             sf->holdlen = remain;
00160          }
00161          continue;
00162       }
00163       
00164       if ((frame_ptr = AST_LIST_REMOVE_HEAD(&sf->queue, frame_list))) {
00165          frame_data = frame_ptr->data.ptr;
00166          
00167          if (frame_ptr->samples <= ineed) {
00168             memcpy(offset, frame_data, frame_ptr->samples * sizeof(*offset));
00169             sofar += frame_ptr->samples;
00170             offset += frame_ptr->samples;
00171          } else {
00172             remain = frame_ptr->samples - ineed;
00173             memcpy(offset, frame_data, ineed * sizeof(*offset));
00174             sofar += ineed;
00175             frame_data += ineed;
00176             if (remain > (AST_SLINFACTORY_MAX_HOLD - sf->holdlen)) {
00177                remain = AST_SLINFACTORY_MAX_HOLD - sf->holdlen;
00178             }
00179             memcpy(sf->hold, frame_data, remain * sizeof(*offset));
00180             sf->holdlen = remain;
00181          }
00182          ast_frfree(frame_ptr);
00183       } else {
00184          break;
00185       }
00186    }
00187 
00188    sf->size -= sofar;
00189    return sofar;
00190 }
00191 
00192 unsigned int ast_slinfactory_available(const struct ast_slinfactory *sf)
00193 {
00194    return sf->size;
00195 }
00196 
00197 void ast_slinfactory_flush(struct ast_slinfactory *sf)
00198 {
00199    struct ast_frame *fr = NULL;
00200 
00201    if (sf->trans) {
00202       ast_translator_free_path(sf->trans);
00203       sf->trans = NULL;
00204    }
00205 
00206    while ((fr = AST_LIST_REMOVE_HEAD(&sf->queue, frame_list)))
00207       ast_frfree(fr);
00208 
00209    sf->size = sf->holdlen = 0;
00210    sf->offset = sf->hold;
00211 
00212    return;
00213 }