formats/format_gsm.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 Save to raw, headerless GSM data.
  22  * \arg File name extension: gsm
  23  * \ingroup formats
  24  */
  25
  26 #include "asterisk.h"
  27
  28 ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
  29
  30 #include "asterisk/mod_format.h"
  31 #include "asterisk/module.h"
  32 #include "asterisk/endian.h"
  33
  34 #include "msgsm.h"
  35
  36 /* Some Ideas for this code came from makegsme.c by Jeffrey Chilton */
  37
  38 /* Portions of the conversion code are by guido@sienanet.it */
  39
  40 #define GSM_FRAME_SIZE  33
  41 #define GSM_SAMPLES     160
  42
  43 /* silent gsm frame */
  44 /* begin binary data: */
  45 char gsm_silence[] = /* 33 */
  46 {0xD8,0x20,0xA2,0xE1,0x5A,0x50,0x00,0x49,0x24,0x92,0x49,0x24,0x50,0x00,0x49
  47 ,0x24,0x92,0x49,0x24,0x50,0x00,0x49,0x24,0x92,0x49,0x24,0x50,0x00,0x49,0x24
  48 ,0x92,0x49,0x24};
  49 /* end binary data. size = 33 bytes */
  50
  51 static struct ast_frame *gsm_read(struct ast_filestream *s, int *whennext)
  52 {
  53         int res;
  54
  55         s->fr.frametype = AST_FRAME_VOICE;
  56         s->fr.subclass = AST_FORMAT_GSM;
  57         AST_FRAME_SET_BUFFER(&(s->fr), s->buf, AST_FRIENDLY_OFFSET, GSM_FRAME_SIZE)
  58         s->fr.mallocd = 0;
  59         if ((res = fread(s->fr.data.ptr, 1, GSM_FRAME_SIZE, s->f)) != GSM_FRAME_SIZE) {
  60                 if (res)
  61                         ast_log(LOG_WARNING, "Short read (%d) (%s)!\n", res, strerror(errno));
  62                 return NULL;
  63         }
  64         *whennext = s->fr.samples = GSM_SAMPLES;
  65         return &s->fr;
  66 }
  67
  68 static int gsm_write(struct ast_filestream *fs, struct ast_frame *f)
  69 {
  70         int res;
  71         unsigned char gsm[2*GSM_FRAME_SIZE];
  72
  73         if (f->frametype != AST_FRAME_VOICE) {
  74                 ast_log(LOG_WARNING, "Asked to write non-voice frame!\n");
  75                 return -1;
  76         }
  77         if (f->subclass != AST_FORMAT_GSM) {
  78                 ast_log(LOG_WARNING, "Asked to write non-GSM frame (%d)!\n", f->subclass);
  79                 return -1;
  80         }
  81         if (!(f->datalen % 65)) {
  82                 /* This is in MSGSM format, need to be converted */
  83                 int len=0;
  84                 while(len < f->datalen) {
  85                         conv65(f->data.ptr + len, gsm);
  86                         if ((res = fwrite(gsm, 1, 2*GSM_FRAME_SIZE, fs->f)) != 2*GSM_FRAME_SIZE) {
  87                                 ast_log(LOG_WARNING, "Bad write (%d/66): %s\n", res, strerror(errno));
  88                                 return -1;
  89                         }
  90                         len += 65;
  91                 }
  92         } else {
  93                 if (f->datalen % GSM_FRAME_SIZE) {
  94                         ast_log(LOG_WARNING, "Invalid data length, %d, should be multiple of 33\n", f->datalen);
  95                         return -1;
  96                 }
  97                 if ((res = fwrite(f->data.ptr, 1, f->datalen, fs->f)) != f->datalen) {
  98                                 ast_log(LOG_WARNING, "Bad write (%d/33): %s\n", res, strerror(errno));
  99                                 return -1;
 100                 }
 101         }
 102         return 0;
 103 }
 104
 105 static int gsm_seek(struct ast_filestream *fs, off_t sample_offset, int whence)
 106 {
 107         off_t offset=0,min,cur,max,distance;
 108
 109         min = 0;
 110         cur = ftello(fs->f);
 111         fseeko(fs->f, 0, SEEK_END);
 112         max = ftello(fs->f);
 113         /* have to fudge to frame here, so not fully to sample */
 114         distance = (sample_offset/GSM_SAMPLES) * GSM_FRAME_SIZE;
 115         if(whence == SEEK_SET)
 116                 offset = distance;
 117         else if(whence == SEEK_CUR || whence == SEEK_FORCECUR)
 118                 offset = distance + cur;
 119         else if(whence == SEEK_END)
 120                 offset = max - distance;
 121         /* Always protect against seeking past the begining. */
 122         offset = (offset < min)?min:offset;
 123         if (whence != SEEK_FORCECUR) {
 124                 offset = (offset > max)?max:offset;
 125         } else if (offset > max) {
 126                 int i;
 127                 fseeko(fs->f, 0, SEEK_END);
 128                 for (i=0; i< (offset - max) / GSM_FRAME_SIZE; i++) {
 129                         fwrite(gsm_silence, 1, GSM_FRAME_SIZE, fs->f);
 130                 }
 131         }
 132         return fseeko(fs->f, offset, SEEK_SET);
 133 }
 134
 135 static int gsm_trunc(struct ast_filestream *fs)
 136 {
 137         return ftruncate(fileno(fs->f), ftello(fs->f));
 138 }
 139
 140 static off_t gsm_tell(struct ast_filestream *fs)
 141 {
 142         off_t offset = ftello(fs->f);
 143         return (offset/GSM_FRAME_SIZE)*GSM_SAMPLES;
 144 }
 145
 146 static const struct ast_format gsm_f = {
 147         .name = "gsm",
 148         .exts = "gsm",
 149         .format = AST_FORMAT_GSM,
 150         .write = gsm_write,
 151         .seek = gsm_seek,
 152         .trunc = gsm_trunc,
 153         .tell = gsm_tell,
 154         .read = gsm_read,
 155         .buf_size = 2*GSM_FRAME_SIZE + AST_FRIENDLY_OFFSET,     /* 2 gsm frames */
 156 };
 157
 158 static int load_module(void)
 159 {
 160         if (ast_format_register(&gsm_f))
 161                 return AST_MODULE_LOAD_FAILURE;
 162         return AST_MODULE_LOAD_SUCCESS;
 163 }
 164
 165 static int unload_module(void)
 166 {
 167         return ast_format_unregister(gsm_f.name);
 168 }
 169
 170 AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Raw GSM data");