Mon Mar 19 11:30:27 2012

Asterisk developer's documentation


format_sln.c

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00001 /*
00002  * Asterisk -- An open source telephony toolkit.
00003  *
00004  * Copyright (C) 1999 - 2005, Anthony Minessale
00005  * Anthony Minessale (anthmct@yahoo.com)
00006  *
00007  * See http://www.asterisk.org for more information about
00008  * the Asterisk project. Please do not directly contact
00009  * any of the maintainers of this project for assistance;
00010  * the project provides a web site, mailing lists and IRC
00011  * channels for your use.
00012  *
00013  * This program is free software, distributed under the terms of
00014  * the GNU General Public License Version 2. See the LICENSE file
00015  * at the top of the source tree.
00016  */
00017 
00018 /*! \file
00019  *
00020  * \brief RAW SLINEAR Format
00021  * \arg File name extensions: sln, raw
00022  * \ingroup formats
00023  */
00024 
00025 /*** MODULEINFO
00026    <support_level>core</support_level>
00027  ***/
00028  
00029 #include "asterisk.h"
00030 
00031 ASTERISK_FILE_VERSION(__FILE__, "$Revision: 328209 $")
00032 
00033 #include "asterisk/mod_format.h"
00034 #include "asterisk/module.h"
00035 #include "asterisk/endian.h"
00036 
00037 #define BUF_SIZE  320      /* 320 bytes, 160 samples */
00038 #define  SLIN_SAMPLES   160
00039 
00040 static struct ast_frame *slinear_read(struct ast_filestream *s, int *whennext)
00041 {
00042    int res;
00043    /* Send a frame from the file to the appropriate channel */
00044 
00045    s->fr.frametype = AST_FRAME_VOICE;
00046    s->fr.subclass.codec = AST_FORMAT_SLINEAR;
00047    s->fr.mallocd = 0;
00048    AST_FRAME_SET_BUFFER(&s->fr, s->buf, AST_FRIENDLY_OFFSET, BUF_SIZE);
00049    if ((res = fread(s->fr.data.ptr, 1, s->fr.datalen, s->f)) < 1) {
00050       if (res)
00051          ast_log(LOG_WARNING, "Short read (%d) (%s)!\n", res, strerror(errno));
00052       return NULL;
00053    }
00054    *whennext = s->fr.samples = res/2;
00055    s->fr.datalen = res;
00056    return &s->fr;
00057 }
00058 
00059 static int slinear_write(struct ast_filestream *fs, struct ast_frame *f)
00060 {
00061    int res;
00062    if (f->frametype != AST_FRAME_VOICE) {
00063       ast_log(LOG_WARNING, "Asked to write non-voice frame!\n");
00064       return -1;
00065    }
00066    if (f->subclass.codec != AST_FORMAT_SLINEAR) {
00067       ast_log(LOG_WARNING, "Asked to write non-slinear frame (%s)!\n", ast_getformatname(f->subclass.codec));
00068       return -1;
00069    }
00070    if ((res = fwrite(f->data.ptr, 1, f->datalen, fs->f)) != f->datalen) {
00071          ast_log(LOG_WARNING, "Bad write (%d/%d): %s\n", res, f->datalen, strerror(errno));
00072          return -1;
00073    }
00074    return 0;
00075 }
00076 
00077 static int slinear_seek(struct ast_filestream *fs, off_t sample_offset, int whence)
00078 {
00079    off_t offset=0,min,cur,max;
00080 
00081    min = 0;
00082    sample_offset <<= 1;
00083    cur = ftello(fs->f);
00084    fseeko(fs->f, 0, SEEK_END);
00085    max = ftello(fs->f);
00086    if (whence == SEEK_SET)
00087       offset = sample_offset;
00088    else if (whence == SEEK_CUR || whence == SEEK_FORCECUR)
00089       offset = sample_offset + cur;
00090    else if (whence == SEEK_END)
00091       offset = max - sample_offset;
00092    if (whence != SEEK_FORCECUR) {
00093       offset = (offset > max)?max:offset;
00094    }
00095    /* always protect against seeking past begining. */
00096    offset = (offset < min)?min:offset;
00097    return fseeko(fs->f, offset, SEEK_SET);
00098 }
00099 
00100 static int slinear_trunc(struct ast_filestream *fs)
00101 {
00102    return ftruncate(fileno(fs->f), ftello(fs->f));
00103 }
00104 
00105 static off_t slinear_tell(struct ast_filestream *fs)
00106 {
00107    return ftello(fs->f) / 2;
00108 }
00109 
00110 static const struct ast_format slin_f = {
00111    .name = "sln",
00112    .exts = "sln|raw",
00113    .format = AST_FORMAT_SLINEAR,
00114    .write = slinear_write,
00115    .seek = slinear_seek,
00116    .trunc = slinear_trunc,
00117    .tell = slinear_tell,
00118    .read = slinear_read,
00119    .buf_size = BUF_SIZE + AST_FRIENDLY_OFFSET,
00120 };
00121 
00122 static int load_module(void)
00123 {
00124    if (ast_format_register(&slin_f))
00125       return AST_MODULE_LOAD_FAILURE;
00126    return AST_MODULE_LOAD_SUCCESS;
00127 }
00128 
00129 static int unload_module(void)
00130 {
00131    return ast_format_unregister(slin_f.name);
00132 }
00133 
00134 AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_LOAD_ORDER, "Raw Signed Linear Audio support (SLN)",
00135    .load = load_module,
00136    .unload = unload_module,
00137    .load_pri = AST_MODPRI_APP_DEPEND
00138 );

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