format_g726.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (c) 2004 - 2005, inAccess Networks
 *
 * Michael Manousos <manousos@inaccessnetworks.com>
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */
 
/*!\file
 *
 * \brief Headerless G.726 (16/24/32/40kbps) data format for Asterisk.
 *
 * File name extensions:
 * \arg 40 kbps: g726-40
 * \arg 32 kbps: g726-32
 * \arg 24 kbps: g726-24
 * \arg 16 kbps: g726-16
 * \ingroup formats
 */
 
/*** MODULEINFO
    <support_level>core</support_level>
 ***/
 
#include "asterisk.h"
 
#include "asterisk/mod_format.h"
#include "asterisk/module.h"
#include "asterisk/endian.h"
#include "asterisk/format_cache.h"
 
#define RATE_40     0
#define RATE_32     1
#define RATE_24     2
#define RATE_16     3
 
/* We can only read/write chunks of FRAME_TIME ms G.726 data */
#define FRAME_TIME  10  /* 10 ms size */
 
#define BUF_SIZE    (5*FRAME_TIME)  /* max frame size in bytes ? */
/* Frame sizes in bytes */
static int frame_size[4] = {
        FRAME_TIME * 5,
        FRAME_TIME * 4,
        FRAME_TIME * 3,
        FRAME_TIME * 2
};
 
struct g726_desc  {
    int rate;   /* RATE_* defines */
};
 
/*
 * Rate dependant format functions (open, rewrite)
 */
static int g726_open(struct ast_filestream *tmp, int rate)
{
    struct g726_desc *s = (struct g726_desc *)tmp->_private;
    s->rate = rate;
    ast_debug(1, "Created filestream G.726-%dk.\n", 40 - s->rate * 8);
    return 0;
}
 
static int g726_40_open(struct ast_filestream *s)
{
    return g726_open(s, RATE_40);
}
 
static int g726_32_open(struct ast_filestream *s)
{
    return g726_open(s, RATE_32);
}
 
static int g726_24_open(struct ast_filestream *s)
{
    return g726_open(s, RATE_24);
}
 
static int g726_16_open(struct ast_filestream *s)
{
    return g726_open(s, RATE_16);
}
 
static int g726_40_rewrite(struct ast_filestream *s, const char *comment)
{
    return g726_open(s, RATE_40);
}
 
static int g726_32_rewrite(struct ast_filestream *s, const char *comment)
{
    return g726_open(s, RATE_32);
}
 
static int g726_24_rewrite(struct ast_filestream *s, const char *comment)
{
    return g726_open(s, RATE_24);
}
 
static int g726_16_rewrite(struct ast_filestream *s, const char *comment)
{
    return g726_open(s, RATE_16);
}
 
/*
 * Rate independent format functions (read, write)
 */
 
static struct ast_frame *g726_read(struct ast_filestream *s, int *whennext)
{
    size_t res;
    struct g726_desc *fs = (struct g726_desc *)s->_private;
 
    /* Send a frame from the file to the appropriate channel */
    AST_FRAME_SET_BUFFER(&s->fr, s->buf, AST_FRIENDLY_OFFSET, frame_size[fs->rate]);
    s->fr.samples = 8 * FRAME_TIME;
    if ((res = fread(s->fr.data.ptr, 1, s->fr.datalen, s->f)) != s->fr.datalen) {
        if (res) {
            ast_log(LOG_WARNING, "Short read of %s data (expected %d bytes, read %zu): %s\n",
                    ast_format_get_name(s->fr.subclass.format), s->fr.datalen, res,
                    strerror(errno));
        }
        return NULL;
    }
    *whennext = s->fr.samples;
    return &s->fr;
}
 
static int g726_write(struct ast_filestream *s, struct ast_frame *f)
{
    int res;
    struct g726_desc *fs = (struct g726_desc *)s->_private;
 
    if (f->datalen % frame_size[fs->rate]) {
        ast_log(LOG_WARNING, "Invalid data length %d, should be multiple of %d\n",
                        f->datalen, frame_size[fs->rate]);
        return -1;
    }
    if ((res = fwrite(f->data.ptr, 1, f->datalen, s->f)) != f->datalen) {
        ast_log(LOG_WARNING, "Bad write (%d/%d): %s\n",
                res, frame_size[fs->rate], strerror(errno));
            return -1;
    }
    return 0;
}
 
static int g726_seek(struct ast_filestream *fs, off_t sample_offset, int whence)
{
    off_t offset = 0, min = 0, cur, max, distance;
 
    if ((cur = ftello(fs->f)) < 0) {
        ast_log(AST_LOG_WARNING, "Unable to determine current position in g726 filestream %p: %s\n", fs, strerror(errno));
        return -1;
    }
 
    if (fseeko(fs->f, 0, SEEK_END) < 0) {
        ast_log(AST_LOG_WARNING, "Unable to seek to end of g726 filestream %p: %s\n", fs, strerror(errno));
        return -1;
    }
 
    if ((max = ftello(fs->f)) < 0) {
        ast_log(AST_LOG_WARNING, "Unable to determine max position in g726 filestream %p: %s\n", fs, strerror(errno));
        return -1;
    }
 
    /* have to fudge to frame here, so not fully to sample */
    distance = sample_offset / 2;
    if (whence == SEEK_SET) {
        offset = distance;
    } else if (whence == SEEK_CUR || whence == SEEK_FORCECUR) {
        offset = distance + cur;
    } else if (whence == SEEK_END) {
        offset = max - distance;
    }
 
    if (whence != SEEK_FORCECUR) {
        offset = offset > max ? max : offset;
        offset = offset < min ? min : offset;
    }
    return fseeko(fs->f, offset, SEEK_SET);
}
 
static int g726_trunc(struct ast_filestream *fs)
{
    return -1;
}
 
static off_t g726_tell(struct ast_filestream *fs)
{
    return ftello(fs->f) << 1;
}
 
static struct ast_format_def f_def[] = {
    {
        .name = "g726-40",
        .exts = "g726-40",
        .open = g726_40_open,
        .rewrite = g726_40_rewrite,
        .write = g726_write,
        .seek = g726_seek,
        .trunc = g726_trunc,
        .tell = g726_tell,
        .read = g726_read,
        .buf_size = BUF_SIZE + AST_FRIENDLY_OFFSET,
        .desc_size = sizeof(struct g726_desc),
    },
    {
        .name = "g726-32",
        .exts = "g726-32",
        .open = g726_32_open,
        .rewrite = g726_32_rewrite,
        .write = g726_write,
        .seek = g726_seek,
        .trunc = g726_trunc,
        .tell = g726_tell,
        .read = g726_read,
        .buf_size = BUF_SIZE + AST_FRIENDLY_OFFSET,
        .desc_size = sizeof(struct g726_desc),
    },
    {
        .name = "g726-24",
        .exts = "g726-24",
        .open = g726_24_open,
        .rewrite = g726_24_rewrite,
        .write = g726_write,
        .seek = g726_seek,
        .trunc = g726_trunc,
        .tell = g726_tell,
        .read = g726_read,
        .buf_size = BUF_SIZE + AST_FRIENDLY_OFFSET,
        .desc_size = sizeof(struct g726_desc),
    },
    {
        .name = "g726-16",
        .exts = "g726-16",
        .open = g726_16_open,
        .rewrite = g726_16_rewrite,
        .write = g726_write,
        .seek = g726_seek,
        .trunc = g726_trunc,
        .tell = g726_tell,
        .read = g726_read,
        .buf_size = BUF_SIZE + AST_FRIENDLY_OFFSET,
        .desc_size = sizeof(struct g726_desc),
    },
    {   .desc_size = 0 }    /* terminator */
};
 
static int unload_module(void)
{
    int i;
 
    for (i = 0; f_def[i].desc_size ; i++) {
        if (ast_format_def_unregister(f_def[i].name))
            ast_log(LOG_WARNING, "Failed to unregister format %s.\n", f_def[i].name);
    }
    return(0);
}
 
static int load_module(void)
{
    int i;
 
    for (i = 0; f_def[i].desc_size ; i++) {
        f_def[i].format = ast_format_g726;
        if (ast_format_def_register(&f_def[i])) {   /* errors are fatal */
            ast_log(LOG_WARNING, "Failed to register format %s.\n", f_def[i].name);
            unload_module();
            return AST_MODULE_LOAD_DECLINE;
        }
    }
    return AST_MODULE_LOAD_SUCCESS;
}
 
AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_LOAD_ORDER, "Raw G.726 (16/24/32/40kbps) data",
    .support_level = AST_MODULE_SUPPORT_CORE,
    .load = load_module,
    .unload = unload_module,
    .load_pri = AST_MODPRI_APP_DEPEND
);