asterisk/channels/iax2/format_compatibility.c

135 lines
3.5 KiB
C

/*
* Asterisk -- An open source telephony toolkit.
*
* Copyright (C) 2014, Digium, Inc.
*
* Joshua Colp <jcolp@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 Media Format Bitfield Compatibility API
*
* \author Joshua Colp <jcolp@digium.com>
*/
/*** MODULEINFO
<support_level>core</support_level>
***/
#include "asterisk.h"
#include "asterisk/logger.h"
#include "asterisk/astobj2.h"
#include "asterisk/codec.h"
#include "asterisk/format.h"
#include "asterisk/format_compatibility.h"
#include "asterisk/format_cache.h"
#include "asterisk/format_cap.h"
#include "asterisk/utils.h"
#include "include/format_compatibility.h"
uint64_t iax2_format_compatibility_cap2bitfield(const struct ast_format_cap *cap)
{
uint64_t bitfield = 0;
int x;
for (x = 0; x < ast_format_cap_count(cap); x++) {
struct ast_format *format = ast_format_cap_get_format(cap, x);
bitfield |= ast_format_compatibility_format2bitfield(format);
ao2_ref(format, -1);
}
return bitfield;
}
int iax2_format_compatibility_bitfield2cap(uint64_t bitfield, struct ast_format_cap *cap)
{
int bit;
for (bit = 0; bit < 64; ++bit) {
uint64_t mask = (1ULL << bit);
if (mask & bitfield) {
struct ast_format *format;
format = ast_format_compatibility_bitfield2format(mask);
if (format && ast_format_cap_append(cap, format, 0)) {
return -1;
}
}
}
return 0;
}
uint64_t iax2_format_compatibility_best(uint64_t formats)
{
/*
* This just our opinion, expressed in code. We are
* asked to choose the best codec to use, given no
* information.
*/
static const uint64_t best[] = {
/*! Okay, ulaw is used by all telephony equipment, so start with it */
AST_FORMAT_ULAW,
/*! Unless of course, you're a silly European, so then prefer ALAW */
AST_FORMAT_ALAW,
AST_FORMAT_G719,
AST_FORMAT_SIREN14,
AST_FORMAT_SIREN7,
AST_FORMAT_TESTLAW,
/*! G.722 is better then all below, but not as common as the above... so give ulaw and alaw priority */
AST_FORMAT_G722,
/*! Okay, well, signed linear is easy to translate into other stuff */
AST_FORMAT_SLIN16,
AST_FORMAT_SLIN,
/*! G.726 is standard ADPCM, in RFC3551 packing order */
AST_FORMAT_G726,
/*! G.726 is standard ADPCM, in AAL2 packing order */
AST_FORMAT_G726_AAL2,
/*! ADPCM has great sound quality and is still pretty easy to translate */
AST_FORMAT_ADPCM,
/*! Okay, we're down to vocoders now, so pick GSM because it's small and easier to
translate and sounds pretty good */
AST_FORMAT_GSM,
/*! iLBC is not too bad */
AST_FORMAT_ILBC,
/*! Speex is free, but computationally more expensive than GSM */
AST_FORMAT_SPEEX16,
AST_FORMAT_SPEEX,
/*! Opus */
AST_FORMAT_OPUS,
/*! Ick, LPC10 sounds terrible, but at least we have code for it, if you're tacky enough
to use it */
AST_FORMAT_LPC10,
/*! G.729a is faster than 723 and slightly less expensive */
AST_FORMAT_G729,
/*! Down to G.723.1 which is proprietary but at least designed for voice */
AST_FORMAT_G723,
};
int idx;
/* Find the first preferred codec in the format given */
for (idx = 0; idx < ARRAY_LEN(best); ++idx) {
if (formats & best[idx]) {
return best[idx];
}
}
return 0;
}