Thu Sep 7 01:03:00 2017

Asterisk developer's documentation


format_sln16.c

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00001 /*
00002  * Asterisk -- An open source telephony toolkit.
00003  *
00004  * Copyright (C) 1999 - 2008, Anthony Minessale and Digium, Inc.
00005  * Anthony Minessale (anthmct@yahoo.com)
00006  * Kevin P. Fleming <kpfleming@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 RAW SLINEAR 16 Format
00022  * \arg File name extensions: sln16
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: 364578 $")
00033 
00034 #include "asterisk/mod_format.h"
00035 #include "asterisk/module.h"
00036 #include "asterisk/endian.h"
00037 
00038 #define BUF_SIZE  640      /* 640 bytes, 320 samples */
00039 #define  SLIN_SAMPLES   320
00040 
00041 static struct ast_frame *slinear_read(struct ast_filestream *s, int *whennext)
00042 {
00043    int res;
00044    /* Send a frame from the file to the appropriate channel */
00045 
00046    s->fr.frametype = AST_FRAME_VOICE;
00047    s->fr.subclass.codec = AST_FORMAT_SLINEAR16;
00048    s->fr.mallocd = 0;
00049    AST_FRAME_SET_BUFFER(&s->fr, s->buf, AST_FRIENDLY_OFFSET, BUF_SIZE);
00050    if ((res = fread(s->fr.data.ptr, 1, s->fr.datalen, s->f)) < 1) {
00051       if (res)
00052          ast_log(LOG_WARNING, "Short read (%d) (%s)!\n", res, strerror(errno));
00053       return NULL;
00054    }
00055    *whennext = s->fr.samples = res/2;
00056    s->fr.datalen = res;
00057    return &s->fr;
00058 }
00059 
00060 static int slinear_write(struct ast_filestream *fs, struct ast_frame *f)
00061 {
00062    int res;
00063 
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_SLINEAR16) {
00069       ast_log(LOG_WARNING, "Asked to write non-slinear16 frame (%s)!\n", ast_getformatname(f->subclass.codec));
00070       return -1;
00071    }
00072    if ((res = fwrite(f->data.ptr, 1, f->datalen, fs->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 slinear_seek(struct ast_filestream *fs, off_t sample_offset, int whence)
00080 {
00081    off_t offset = 0, min = 0, cur, max;
00082 
00083    sample_offset <<= 1;
00084 
00085    if ((cur = ftello(fs->f)) < 0) {
00086       ast_log(AST_LOG_WARNING, "Unable to determine current position in sln16 filestream %p: %s\n", fs, strerror(errno));
00087       return -1;
00088    }
00089 
00090    if (fseeko(fs->f, 0, SEEK_END) < 0) {
00091       ast_log(AST_LOG_WARNING, "Unable to seek to end of sln16 filestream %p: %s\n", fs, strerror(errno));
00092       return -1;
00093    }
00094 
00095    if ((max = ftello(fs->f)) < 0) {
00096       ast_log(AST_LOG_WARNING, "Unable to determine max position in sln16 filestream %p: %s\n", fs, strerror(errno));
00097       return -1;
00098    }
00099 
00100    if (whence == SEEK_SET)
00101       offset = sample_offset;
00102    else if (whence == SEEK_CUR || whence == SEEK_FORCECUR)
00103       offset = sample_offset + cur;
00104    else if (whence == SEEK_END)
00105       offset = max - sample_offset;
00106 
00107    if (whence != SEEK_FORCECUR)
00108       offset = (offset > max) ? max : offset;
00109 
00110    /* always protect against seeking past begining. */
00111    offset = (offset < min) ? min : offset;
00112 
00113    return fseeko(fs->f, offset, SEEK_SET);
00114 }
00115 
00116 static int slinear_trunc(struct ast_filestream *fs)
00117 {
00118    int fd;
00119    off_t cur;
00120 
00121    if ((fd = fileno(fs->f)) < 0) {
00122       ast_log(AST_LOG_WARNING, "Unable to determine file descriptor for sln16 filestream %p: %s\n", fs, strerror(errno));
00123       return -1;
00124    }
00125    if ((cur = ftello(fs->f)) < 0) {
00126       ast_log(AST_LOG_WARNING, "Unable to determine current position in sln16 filestream %p: %s\n", fs, strerror(errno));
00127       return -1;
00128    }
00129    /* Truncate file to current length */
00130    return ftruncate(fd, cur);
00131 }
00132 
00133 static off_t slinear_tell(struct ast_filestream *fs)
00134 {
00135    return ftello(fs->f) / 2;
00136 }
00137 
00138 static const struct ast_format slin_f = {
00139    .name = "sln16",
00140    .exts = "sln16",
00141    .format = AST_FORMAT_SLINEAR16,
00142    .write = slinear_write,
00143    .seek = slinear_seek,
00144    .trunc = slinear_trunc,
00145    .tell = slinear_tell,
00146    .read = slinear_read,
00147    .buf_size = BUF_SIZE + AST_FRIENDLY_OFFSET,
00148 };
00149 
00150 static int load_module(void)
00151 {
00152    if (ast_format_register(&slin_f))
00153       return AST_MODULE_LOAD_FAILURE;
00154 
00155    return AST_MODULE_LOAD_SUCCESS;
00156 }
00157 
00158 static int unload_module(void)
00159 {
00160    return ast_format_unregister(slin_f.name);
00161 }
00162 
00163 AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_LOAD_ORDER, "Raw Signed Linear 16KHz Audio support (SLN16)",
00164    .load = load_module,
00165    .unload = unload_module,
00166    .load_pri = AST_MODPRI_APP_DEPEND
00167 );

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