Sat Mar 10 01:54:17 2012

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: 328209 $")
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    cur = ftello(fs->f);
00086 
00087    fseeko(fs->f, 0, SEEK_END);
00088 
00089    max = ftello(fs->f);
00090 
00091    if (whence == SEEK_SET)
00092       offset = sample_offset;
00093    else if (whence == SEEK_CUR || whence == SEEK_FORCECUR)
00094       offset = sample_offset + cur;
00095    else if (whence == SEEK_END)
00096       offset = max - sample_offset;
00097 
00098    if (whence != SEEK_FORCECUR)
00099       offset = (offset > max) ? max : offset;
00100 
00101    /* always protect against seeking past begining. */
00102    offset = (offset < min) ? min : offset;
00103 
00104    return fseeko(fs->f, offset, SEEK_SET);
00105 }
00106 
00107 static int slinear_trunc(struct ast_filestream *fs)
00108 {
00109    return ftruncate(fileno(fs->f), ftello(fs->f));
00110 }
00111 
00112 static off_t slinear_tell(struct ast_filestream *fs)
00113 {
00114    return ftello(fs->f) / 2;
00115 }
00116 
00117 static const struct ast_format slin_f = {
00118    .name = "sln16",
00119    .exts = "sln16",
00120    .format = AST_FORMAT_SLINEAR16,
00121    .write = slinear_write,
00122    .seek = slinear_seek,
00123    .trunc = slinear_trunc,
00124    .tell = slinear_tell,
00125    .read = slinear_read,
00126    .buf_size = BUF_SIZE + AST_FRIENDLY_OFFSET,
00127 };
00128 
00129 static int load_module(void)
00130 {
00131    if (ast_format_register(&slin_f))
00132       return AST_MODULE_LOAD_FAILURE;
00133 
00134    return AST_MODULE_LOAD_SUCCESS;
00135 }
00136 
00137 static int unload_module(void)
00138 {
00139    return ast_format_unregister(slin_f.name);
00140 }
00141 
00142 AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_LOAD_ORDER, "Raw Signed Linear 16KHz Audio support (SLN16)",
00143    .load = load_module,
00144    .unload = unload_module,
00145    .load_pri = AST_MODPRI_APP_DEPEND
00146 );

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