format_g719.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2010, Anthony Minessale and Digium, Inc.
 * Anthony Minessale (anthmct@yahoo.com)
 * Kevin P. Fleming <kpfleming@digium.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 ITU G.719 , 64kbps bitrate only
 * \arg File name extensions: g719
 * \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 BUF_SIZE    160     /* 20 milliseconds == 160 bytes, 960 samples */
#define SAMPLES_TO_BYTES(x) ((typeof(x)) x / ((float) 960 / 160))
#define BYTES_TO_SAMPLES(x) ((typeof(x)) x * ((float) 960 / 160))
 
static struct ast_frame *g719read(struct ast_filestream *s, int *whennext)
{
    size_t res;
 
    /* Send a frame from the file to the appropriate channel */
    AST_FRAME_SET_BUFFER(&s->fr, s->buf, AST_FRIENDLY_OFFSET, BUF_SIZE);
    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 = BYTES_TO_SAMPLES(res);
    return &s->fr;
}
 
static int g719write(struct ast_filestream *fs, struct ast_frame *f)
{
    int res;
 
    if ((res = fwrite(f->data.ptr, 1, f->datalen, fs->f)) != f->datalen) {
        ast_log(LOG_WARNING, "Bad write (%d/%d): %s\n", res, f->datalen, strerror(errno));
        return -1;
    }
    return 0;
}
 
static int g719seek(struct ast_filestream *fs, off_t sample_offset, int whence)
{
    off_t offset = 0, min = 0, cur, max;
 
    sample_offset = SAMPLES_TO_BYTES(sample_offset);
 
    if ((cur = ftello(fs->f)) < 0) {
        ast_log(AST_LOG_WARNING, "Unable to determine current position in g719 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 g719 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 g719 filestream %p: %s\n", fs, strerror(errno));
        return -1;
    }
 
    if (whence == SEEK_SET)
        offset = sample_offset;
    else if (whence == SEEK_CUR || whence == SEEK_FORCECUR)
        offset = sample_offset + cur;
    else if (whence == SEEK_END)
        offset = max - sample_offset;
 
    if (whence != SEEK_FORCECUR)
        offset = (offset > max) ? max : offset;
 
    /* always protect against seeking past begining. */
    offset = (offset < min) ? min : offset;
 
    return fseeko(fs->f, offset, SEEK_SET);
}
 
static int g719trunc(struct ast_filestream *fs)
{
    int fd;
    off_t cur;
 
    if ((fd = fileno(fs->f)) < 0) {
        ast_log(AST_LOG_WARNING, "Unable to determine file descriptor for g719 filestream %p: %s\n", fs, strerror(errno));
        return -1;
    }
    if ((cur = ftello(fs->f)) < 0) {
        ast_log(AST_LOG_WARNING, "Unable to determine current position in g719 filestream %p: %s\n", fs, strerror(errno));
        return -1;
    }
    return ftruncate(fd, cur);
}
 
static off_t g719tell(struct ast_filestream *fs)
{
    return BYTES_TO_SAMPLES(ftello(fs->f));
}
 
static struct ast_format_def g719_f = {
    .name = "g719",
    .exts = "g719",
    .write = g719write,
    .seek = g719seek,
    .trunc = g719trunc,
    .tell = g719tell,
    .read = g719read,
    .buf_size = BUF_SIZE + AST_FRIENDLY_OFFSET,
};
 
static int load_module(void)
{
    g719_f.format = ast_format_g719;
 
    if (ast_format_def_register(&g719_f))
        return AST_MODULE_LOAD_DECLINE;
    return AST_MODULE_LOAD_SUCCESS;
}
 
static int unload_module(void)
{
    return ast_format_def_unregister(g719_f.name);
}
 
AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_LOAD_ORDER, "ITU G.719",
    .support_level = AST_MODULE_SUPPORT_CORE,
    .load = load_module,
    .unload = unload_module,
    .load_pri = AST_MODPRI_APP_DEPEND
);