format_gsm.c

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00001 /*
00002  * Asterisk -- An open source telephony toolkit.
00003  *
00004  * Copyright (C) 1999 - 2005, Digium, Inc.
00005  *
00006  * Mark Spencer <markster@digium.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 Save to raw, headerless GSM data.
00022  * \arg File name extension: gsm
00023  * \ingroup formats
00024  */
00025 
00026 /*** MODULEINFO
00027    <support_level>core</support_level>
00028  ***/
00029  
00030 #include "asterisk.h"
00031 
00032 ASTERISK_FILE_VERSION(__FILE__, "$Revision: 419592 $")
00033 
00034 #include "asterisk/mod_format.h"
00035 #include "asterisk/module.h"
00036 #include "asterisk/endian.h"
00037 #include "asterisk/format_cache.h"
00038 
00039 #include "msgsm.h"
00040 
00041 /* Some Ideas for this code came from makegsme.c by Jeffrey Chilton */
00042 
00043 /* Portions of the conversion code are by guido@sienanet.it */
00044 
00045 #define  GSM_FRAME_SIZE 33
00046 #define  GSM_SAMPLES 160
00047 
00048 /* silent gsm frame */
00049 /* begin binary data: */
00050 static const char gsm_silence[] = /* 33 */
00051 {0xD8,0x20,0xA2,0xE1,0x5A,0x50,0x00,0x49,0x24,0x92,0x49,0x24,0x50,0x00,0x49
00052 ,0x24,0x92,0x49,0x24,0x50,0x00,0x49,0x24,0x92,0x49,0x24,0x50,0x00,0x49,0x24
00053 ,0x92,0x49,0x24};
00054 /* end binary data. size = 33 bytes */
00055 
00056 static struct ast_frame *gsm_read(struct ast_filestream *s, int *whennext)
00057 {
00058    int res;
00059 
00060    AST_FRAME_SET_BUFFER(&(s->fr), s->buf, AST_FRIENDLY_OFFSET, GSM_FRAME_SIZE)
00061    if ((res = fread(s->fr.data.ptr, 1, GSM_FRAME_SIZE, s->f)) != GSM_FRAME_SIZE) {
00062       if (res)
00063          ast_log(LOG_WARNING, "Short read (%d) (%s)!\n", res, strerror(errno));
00064       return NULL;
00065    }
00066    *whennext = s->fr.samples = GSM_SAMPLES;
00067    return &s->fr;
00068 }
00069 
00070 static int gsm_write(struct ast_filestream *fs, struct ast_frame *f)
00071 {
00072    int res;
00073    unsigned char gsm[2*GSM_FRAME_SIZE];
00074 
00075    if (!(f->datalen % 65)) {
00076       /* This is in MSGSM format, need to be converted */
00077       int len=0;
00078       while(len < f->datalen) {
00079          conv65(f->data.ptr + len, gsm);
00080          if ((res = fwrite(gsm, 1, 2*GSM_FRAME_SIZE, fs->f)) != 2*GSM_FRAME_SIZE) {
00081             ast_log(LOG_WARNING, "Bad write (%d/66): %s\n", res, strerror(errno));
00082             return -1;
00083          }
00084          len += 65;
00085       }
00086    } else {
00087       if (f->datalen % GSM_FRAME_SIZE) {
00088          ast_log(LOG_WARNING, "Invalid data length, %d, should be multiple of 33\n", f->datalen);
00089          return -1;
00090       }
00091       if ((res = fwrite(f->data.ptr, 1, f->datalen, fs->f)) != f->datalen) {
00092             ast_log(LOG_WARNING, "Bad write (%d/33): %s\n", res, strerror(errno));
00093             return -1;
00094       }
00095    }
00096    return 0;
00097 }
00098 
00099 static int gsm_seek(struct ast_filestream *fs, off_t sample_offset, int whence)
00100 {
00101    off_t offset = 0, min = 0, cur, max, distance;
00102 
00103    if ((cur = ftello(fs->f)) < 0) {
00104       ast_log(AST_LOG_WARNING, "Unable to determine current position in g719 filestream %p: %s\n", fs, strerror(errno));
00105       return -1;
00106    }
00107 
00108    if (fseeko(fs->f, 0, SEEK_END) < 0) {
00109       ast_log(AST_LOG_WARNING, "Unable to seek to end of g719 filestream %p: %s\n", fs, strerror(errno));
00110       return -1;
00111    }
00112 
00113    if ((max = ftello(fs->f)) < 0) {
00114       ast_log(AST_LOG_WARNING, "Unable to determine max position in g719 filestream %p: %s\n", fs, strerror(errno));
00115       return -1;
00116    }
00117 
00118    /* have to fudge to frame here, so not fully to sample */
00119    distance = (sample_offset / GSM_SAMPLES) * GSM_FRAME_SIZE;
00120    if (whence == SEEK_SET) {
00121       offset = distance;
00122    } else if (whence == SEEK_CUR || whence == SEEK_FORCECUR) {
00123       offset = distance + cur;
00124    } else if (whence == SEEK_END) {
00125       offset = max - distance;
00126    }
00127 
00128    /* Always protect against seeking past the begining. */
00129    offset = (offset < min)?min:offset;
00130    if (whence != SEEK_FORCECUR) {
00131       offset = (offset > max)?max:offset;
00132    } else if (offset > max) {
00133       int i;
00134       fseeko(fs->f, 0, SEEK_END);
00135       for (i=0; i< (offset - max) / GSM_FRAME_SIZE; i++) {
00136          if (!fwrite(gsm_silence, 1, GSM_FRAME_SIZE, fs->f)) {
00137             ast_log(LOG_WARNING, "fwrite() failed: %s\n", strerror(errno));
00138          }
00139       }
00140    }
00141    return fseeko(fs->f, offset, SEEK_SET);
00142 }
00143 
00144 static int gsm_trunc(struct ast_filestream *fs)
00145 {
00146    int fd;
00147    off_t cur;
00148 
00149    if ((fd = fileno(fs->f)) < 0) {
00150       ast_log(AST_LOG_WARNING, "Unable to determine file descriptor for gsm filestream %p: %s\n", fs, strerror(errno));
00151       return -1;
00152    }
00153    if ((cur = ftello(fs->f)) < 0) {
00154       ast_log(AST_LOG_WARNING, "Unable to determine current position in gsm filestream %p: %s\n", fs, strerror(errno));
00155       return -1;
00156    }
00157    /* Truncate file to current length */
00158    return ftruncate(fd, cur);
00159 }
00160 
00161 static off_t gsm_tell(struct ast_filestream *fs)
00162 {
00163    off_t offset = ftello(fs->f);
00164 
00165    if (offset < 0) {
00166       ast_log(AST_LOG_WARNING, "Unable to determine offset for gsm filestream %p: %s\n", fs, strerror(errno));
00167       return 0;
00168    }
00169 
00170    return (offset / GSM_FRAME_SIZE) * GSM_SAMPLES;
00171 }
00172 
00173 static struct ast_format_def gsm_f = {
00174    .name = "gsm",
00175    .exts = "gsm",
00176    .write = gsm_write,
00177    .seek =  gsm_seek,
00178    .trunc = gsm_trunc,
00179    .tell =  gsm_tell,
00180    .read =  gsm_read,
00181    .buf_size = 2*GSM_FRAME_SIZE + AST_FRIENDLY_OFFSET,   /* 2 gsm frames */
00182 };
00183 
00184 static int load_module(void)
00185 {
00186    gsm_f.format = ast_format_gsm;
00187    if (ast_format_def_register(&gsm_f))
00188       return AST_MODULE_LOAD_FAILURE;
00189    return AST_MODULE_LOAD_SUCCESS;
00190 }
00191 
00192 static int unload_module(void)
00193 {
00194    return ast_format_def_unregister(gsm_f.name);
00195 }
00196 
00197 AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_LOAD_ORDER, "Raw GSM data",
00198    .support_level = AST_MODULE_SUPPORT_CORE,
00199    .load = load_module,
00200    .unload = unload_module,
00201    .load_pri = AST_MODPRI_APP_DEPEND
00202 );

Generated on Thu Apr 16 06:27:34 2015 for Asterisk - The Open Source Telephony Project by  doxygen 1.5.6