codecs/codec_alaw.c

   1 /*
   2  * Asterisk -- An open source telephony toolkit.
   3  *
   4  * Copyright (C) 1999 - 2005, Digium, Inc.
   5  *
   6  * Mark Spencer <markster@digium.com>
   7  *
   8  * See http://www.asterisk.org for more information about
   9  * the Asterisk project. Please do not directly contact
  10  * any of the maintainers of this project for assistance;
  11  * the project provides a web site, mailing lists and IRC
  12  * channels for your use.
  13  *
  14  * This program is free software, distributed under the terms of
  15  * the GNU General Public License Version 2. See the LICENSE file
  16  * at the top of the source tree.
  17  */
  18
  19 /*! \file
  20  *
  21  * \brief codec_alaw.c - translate between signed linear and alaw
  22  *
  23  * \ingroup codecs
  24  */
  25
  26 #include "asterisk.h"
  27
  28 ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
  29
  30 #include "asterisk/module.h"
  31 #include "asterisk/config.h"
  32 #include "asterisk/translate.h"
  33 #include "asterisk/alaw.h"
  34 #include "asterisk/utils.h"
  35
  36 #define BUFFER_SAMPLES   8096   /* size for the translation buffers */
  37
  38 /* Sample frame data (Mu data is okay) */
  39
  40 #include "slin_ulaw_ex.h"
  41 #include "ulaw_slin_ex.h"
  42
  43 /*! \brief decode frame into lin and fill output buffer. */
  44 static int alawtolin_framein(struct ast_trans_pvt *pvt, struct ast_frame *f)
  45 {
  46         int i = f->samples;
  47         unsigned char *src = f->data.ptr;
  48         int16_t *dst = (int16_t *)pvt->outbuf + pvt->samples;
  49
  50         pvt->samples += i;
  51         pvt->datalen += i * 2;  /* 2 bytes/sample */
  52
  53         while (i--)
  54                 *dst++ = AST_ALAW(*src++);
  55
  56         return 0;
  57 }
  58
  59 /*! \brief convert and store input samples in output buffer */
  60 static int lintoalaw_framein(struct ast_trans_pvt *pvt, struct ast_frame *f)
  61 {
  62         int i = f->samples;
  63         char *dst = pvt->outbuf + pvt->samples;
  64         int16_t *src = f->data.ptr;
  65
  66         pvt->samples += i;
  67         pvt->datalen += i;      /* 1 byte/sample */
  68
  69         while (i--)
  70                 *dst++ = AST_LIN2A(*src++);
  71
  72         return 0;
  73 }
  74
  75 /*! \brief alawToLin_Sample */
  76 static struct ast_frame *alawtolin_sample(void)
  77 {
  78         static struct ast_frame f;
  79         f.frametype = AST_FRAME_VOICE;
  80         f.subclass = AST_FORMAT_ALAW;
  81         f.datalen = sizeof(ulaw_slin_ex);
  82         f.samples = sizeof(ulaw_slin_ex);
  83         f.mallocd = 0;
  84         f.offset = 0;
  85         f.src = __PRETTY_FUNCTION__;
  86         f.data.ptr = ulaw_slin_ex;
  87         return &f;
  88 }
  89
  90 /*! \brief LinToalaw_Sample */
  91 static struct ast_frame *lintoalaw_sample(void)
  92 {
  93         static struct ast_frame f;
  94         f.frametype = AST_FRAME_VOICE;
  95         f.subclass = AST_FORMAT_SLINEAR;
  96         f.datalen = sizeof(slin_ulaw_ex);
  97         f.samples = sizeof(slin_ulaw_ex) / 2;
  98         f.mallocd = 0;
  99         f.offset = 0;
 100         f.src = __PRETTY_FUNCTION__;
 101         f.data.ptr = slin_ulaw_ex;
 102         return &f;
 103 }
 104
 105 static struct ast_translator alawtolin = {
 106         .name = "alawtolin",
 107         .srcfmt = AST_FORMAT_ALAW,
 108         .dstfmt = AST_FORMAT_SLINEAR,
 109         .framein = alawtolin_framein,
 110         .sample = alawtolin_sample,
 111         .buffer_samples = BUFFER_SAMPLES,
 112         .buf_size = BUFFER_SAMPLES * 2,
 113         .plc_samples = 160,
 114 };
 115
 116 static struct ast_translator lintoalaw = {
 117         "lintoalaw",
 118         .srcfmt = AST_FORMAT_SLINEAR,
 119         .dstfmt = AST_FORMAT_ALAW,
 120         .framein = lintoalaw_framein,
 121         .sample = lintoalaw_sample,
 122         .buffer_samples = BUFFER_SAMPLES,
 123         .buf_size = BUFFER_SAMPLES,
 124 };
 125
 126 static int parse_config(int reload)
 127 {
 128         struct ast_variable *var;
 129         struct ast_flags config_flags = { reload ? CONFIG_FLAG_FILEUNCHANGED : 0 };
 130         struct ast_config *cfg = ast_config_load("codecs.conf", config_flags);
 131         if (cfg == NULL)
 132                 return 0;
 133         if (cfg == CONFIG_STATUS_FILEUNCHANGED)
 134                 return 0;
 135         for (var = ast_variable_browse(cfg, "plc"); var; var = var->next) {
 136                 if (!strcasecmp(var->name, "genericplc")) {
 137                         alawtolin.useplc = ast_true(var->value) ? 1 : 0;
 138                         ast_verb(3, "codec_alaw: %susing generic PLC\n", alawtolin.useplc ? "" : "not ");
 139                 }
 140         }
 141         ast_config_destroy(cfg);
 142         return 0;
 143 }
 144
 145 /*! \brief standard module stuff */
 146
 147 static int reload(void)
 148 {
 149         if (parse_config(1))
 150                 return AST_MODULE_LOAD_DECLINE;
 151         return AST_MODULE_LOAD_SUCCESS;
 152 }
 153
 154 static int unload_module(void)
 155 {
 156         int res;
 157
 158         res = ast_unregister_translator(&lintoalaw);
 159         res |= ast_unregister_translator(&alawtolin);
 160
 161         return res;
 162 }
 163
 164 static int load_module(void)
 165 {
 166         int res;
 167
 168         if (parse_config(0))
 169                 return AST_MODULE_LOAD_DECLINE;
 170         res = ast_register_translator(&alawtolin);
 171         if (!res)
 172                 res = ast_register_translator(&lintoalaw);
 173         else
 174                 ast_unregister_translator(&alawtolin);
 175         if (res)
 176                 return AST_MODULE_LOAD_FAILURE;
 177         return AST_MODULE_LOAD_SUCCESS;
 178 }
 179
 180 AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_DEFAULT, "A-law Coder/Decoder",
 181                 .load = load_module,
 182                 .unload = unload_module,
 183                 .reload = reload,
 184                );