Tue Aug 20 16:34:33 2013

Asterisk developer's documentation


format_vox.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 Flat, binary, ADPCM vox file format.
00022  * \arg File name extensions: vox
00023  * 
00024  * \ingroup formats
00025  */
00026 
00027 /*** MODULEINFO
00028    <support_level>extended</support_level>
00029  ***/
00030  
00031 #include "asterisk.h"
00032 
00033 ASTERISK_FILE_VERSION(__FILE__, "$Revision: 364578 $")
00034 
00035 #include "asterisk/mod_format.h"
00036 #include "asterisk/module.h"
00037 #include "asterisk/endian.h"
00038 
00039 #define BUF_SIZE  80    /* 80 bytes, 160 samples */
00040 #define VOX_SAMPLES  160
00041 
00042 static struct ast_frame *vox_read(struct ast_filestream *s, int *whennext)
00043 {
00044    int res;
00045 
00046    /* Send a frame from the file to the appropriate channel */
00047    s->fr.frametype = AST_FRAME_VOICE;
00048    s->fr.subclass.codec = AST_FORMAT_ADPCM;
00049    s->fr.mallocd = 0;
00050    AST_FRAME_SET_BUFFER(&s->fr, s->buf, AST_FRIENDLY_OFFSET, BUF_SIZE);
00051    if ((res = fread(s->fr.data.ptr, 1, s->fr.datalen, s->f)) < 1) {
00052       if (res)
00053          ast_log(LOG_WARNING, "Short read (%d) (%s)!\n", res, strerror(errno));
00054       return NULL;
00055    }
00056    *whennext = s->fr.samples = res * 2;
00057    s->fr.datalen = res;
00058    return &s->fr;
00059 }
00060 
00061 static int vox_write(struct ast_filestream *s, struct ast_frame *f)
00062 {
00063    int res;
00064    if (f->frametype != AST_FRAME_VOICE) {
00065       ast_log(LOG_WARNING, "Asked to write non-voice frame!\n");
00066       return -1;
00067    }
00068    if (f->subclass.codec != AST_FORMAT_ADPCM) {
00069       ast_log(LOG_WARNING, "Asked to write non-ADPCM frame (%s)!\n", ast_getformatname(f->subclass.codec));
00070       return -1;
00071    }
00072    if ((res = fwrite(f->data.ptr, 1, f->datalen, s->f)) != f->datalen) {
00073          ast_log(LOG_WARNING, "Bad write (%d/%d): %s\n", res, f->datalen, strerror(errno));
00074          return -1;
00075    }
00076    return 0;
00077 }
00078 
00079 static int vox_seek(struct ast_filestream *fs, off_t sample_offset, int whence)
00080 {
00081    off_t offset = 0, min = 0, cur, max, distance;
00082 
00083    if ((cur = ftello(fs->f)) < 0) {
00084       ast_log(AST_LOG_WARNING, "Unable to determine current position in g719 filestream %p: %s\n", fs, strerror(errno));
00085       return -1;
00086    }
00087 
00088    if (fseeko(fs->f, 0, SEEK_END) < 0) {
00089       ast_log(AST_LOG_WARNING, "Unable to seek to end of g719 filestream %p: %s\n", fs, strerror(errno));
00090       return -1;
00091    }
00092 
00093    if ((max = ftello(fs->f)) < 0) {
00094       ast_log(AST_LOG_WARNING, "Unable to determine max position in g719 filestream %p: %s\n", fs, strerror(errno));
00095       return -1;
00096    }
00097 
00098    /* have to fudge to frame here, so not fully to sample */
00099    distance = sample_offset/2;
00100    if (whence == SEEK_SET) {
00101       offset = distance;
00102    } else if (whence == SEEK_CUR || whence == SEEK_FORCECUR) {
00103       offset = distance + cur;
00104    } else if (whence == SEEK_END) {
00105       offset = max - distance;
00106    }
00107    if (whence != SEEK_FORCECUR) {
00108       offset = (offset > max)?max:offset;
00109       offset = (offset < min)?min:offset;
00110    }
00111    return fseeko(fs->f, offset, SEEK_SET);
00112 }
00113 
00114 static int vox_trunc(struct ast_filestream *fs)
00115 {
00116    int fd;
00117    off_t cur;
00118 
00119    if ((fd = fileno(fs->f)) < 0) {
00120       ast_log(AST_LOG_WARNING, "Unable to determine file descriptor for vox filestream %p: %s\n", fs, strerror(errno));
00121       return -1;
00122    }
00123    if ((cur = ftello(fs->f)) < 0) {
00124       ast_log(AST_LOG_WARNING, "Unable to determine current position in vox filestream %p: %s\n", fs, strerror(errno));
00125       return -1;
00126    }
00127    /* Truncate file to current length */
00128    return ftruncate(fd, cur);}
00129 
00130 static off_t vox_tell(struct ast_filestream *fs)
00131 {
00132      off_t offset;
00133      offset = ftello(fs->f) << 1;
00134      return offset; 
00135 }
00136 
00137 static const struct ast_format vox_f = {
00138    .name = "vox",
00139    .exts = "vox",
00140    .format = AST_FORMAT_ADPCM,
00141    .write = vox_write,
00142    .seek = vox_seek,
00143    .trunc = vox_trunc,
00144    .tell = vox_tell,
00145    .read = vox_read,
00146    .buf_size = BUF_SIZE + AST_FRIENDLY_OFFSET,
00147 };
00148 
00149 static int load_module(void)
00150 {
00151    if (ast_format_register(&vox_f))
00152       return AST_MODULE_LOAD_FAILURE;
00153    return AST_MODULE_LOAD_SUCCESS;
00154 }
00155 
00156 static int unload_module(void)
00157 {
00158    return ast_format_unregister(vox_f.name);
00159 }
00160 
00161 AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_LOAD_ORDER, "Dialogic VOX (ADPCM) File Format",
00162    .load = load_module,
00163    .unload = unload_module,
00164    .load_pri = AST_MODPRI_APP_DEPEND
00165 );

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