210 lines
7.5 KiB
C
210 lines
7.5 KiB
C
/* Filter/overlay codec selections for a voice call, across MS, RAN and CN limitations */
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/*
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* (C) 2019-2022 by sysmocom - s.m.f.c. GmbH <info@sysmocom.de>
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* All Rights Reserved
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*
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* Author: Neels Hofmeyr
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*
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* SPDX-License-Identifier: GPL-2.0+
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#include <osmocom/gsm/protocol/gsm_08_08.h>
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#include <osmocom/msc/codec_filter.h>
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#include <osmocom/msc/codec_sdp_cc_t9n.h>
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#include <osmocom/msc/debug.h>
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/* Add all known payload types encountered in GSM networks */
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static void sdp_add_all_mobile_codecs(struct sdp_audio_codecs *ac)
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{
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/* In order of preference. TODO: make configurable */
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static const enum gsm48_bcap_speech_ver mobile_codecs[] = {
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GSM48_BCAP_SV_AMR_F /*!< 4 GSM FR V3 (FR AMR) */,
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GSM48_BCAP_SV_AMR_H /*!< 5 GSM HR V3 (HR_AMR) */,
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GSM48_BCAP_SV_EFR /*!< 2 GSM FR V2 (GSM EFR) */,
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GSM48_BCAP_SV_FR /*!< 0 GSM FR V1 (GSM FR) */,
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GSM48_BCAP_SV_HR /*!< 1 GSM HR V1 (GSM HR) */,
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};
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int i;
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for (i = 0; i < ARRAY_SIZE(mobile_codecs); i++)
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sdp_audio_codecs_add_speech_ver(ac, mobile_codecs[i]);
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}
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/* Add all known AMR payload types encountered in UTRAN networks */
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static void sdp_add_all_utran_codecs(struct sdp_audio_codecs *ac)
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{
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/* In order of preference. TODO: make configurable */
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static const enum gsm48_bcap_speech_ver utran_codecs[] = {
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GSM48_BCAP_SV_AMR_F /*!< 4 GSM FR V3 (FR AMR) */,
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GSM48_BCAP_SV_AMR_H /*!< 5 GSM HR V3 (HR_AMR) */,
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GSM48_BCAP_SV_AMR_OH /*!< 11 GSM HR V6 (OHR AMR) */,
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GSM48_BCAP_SV_AMR_FW /*!< 8 GSM FR V5 (FR AMR-WB) */,
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GSM48_BCAP_SV_AMR_OFW /*!< 6 GSM FR V4 (OFR AMR-WB) */,
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GSM48_BCAP_SV_AMR_OHW /*!< 7 GSM HR V4 (OHR AMR-WB) */,
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};
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int i;
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for (i = 0; i < ARRAY_SIZE(utran_codecs); i++)
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sdp_audio_codecs_add_speech_ver(ac, utran_codecs[i]);
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}
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void codec_filter_init(struct codec_filter *codec_filter)
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{
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*codec_filter = (struct codec_filter){};
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}
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void codec_filter_set_ran(struct codec_filter *codec_filter, enum osmo_rat_type ran_type)
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{
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codec_filter->ran = (struct sdp_audio_codecs){};
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switch (ran_type) {
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default:
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case OSMO_RAT_GERAN_A:
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sdp_add_all_mobile_codecs(&codec_filter->ran);
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break;
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case OSMO_RAT_UTRAN_IU:
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sdp_add_all_utran_codecs(&codec_filter->ran);
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break;
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}
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}
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void codec_filter_set_ms_from_bc(struct codec_filter *codec_filter, const struct gsm_mncc_bearer_cap *ms_bearer_cap)
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{
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codec_filter->ms = (struct sdp_audio_codecs){0};
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if (ms_bearer_cap)
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sdp_audio_codecs_from_bearer_cap(&codec_filter->ms, ms_bearer_cap);
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}
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void codec_filter_set_bss(struct codec_filter *codec_filter,
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const struct gsm0808_speech_codec_list *codec_list_bss_supported)
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{
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codec_filter->bss = (struct sdp_audio_codecs){};
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if (codec_list_bss_supported)
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sdp_audio_codecs_from_speech_codec_list(&codec_filter->bss, codec_list_bss_supported);
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}
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int codec_filter_set_remote(struct codec_filter *codec_filter, const char *remote_sdp)
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{
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return sdp_msg_from_sdp_str(&codec_filter->remote, remote_sdp);
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}
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void codec_filter_set_local_rtp(struct codec_filter *codec_filter, const struct osmo_sockaddr_str *rtp)
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{
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if (!rtp)
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codec_filter->result.rtp = (struct osmo_sockaddr_str){0};
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else
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codec_filter->result.rtp = *rtp;
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}
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/* Render intersections of all known audio codec constraints to reach a resulting choice of favorite audio codec, plus
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* possible set of alternative audio codecs, in codec_filter->result. (The result.rtp address remains unchanged.) */
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int codec_filter_run(struct codec_filter *codec_filter)
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{
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struct sdp_audio_codecs *r = &codec_filter->result.audio_codecs;
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struct sdp_audio_codec *a = &codec_filter->assignment;
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*r = codec_filter->ran;
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if (codec_filter->ms.count)
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sdp_audio_codecs_intersection(r, &codec_filter->ms, false);
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if (codec_filter->bss.count)
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sdp_audio_codecs_intersection(r, &codec_filter->bss, false);
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if (codec_filter->remote.audio_codecs.count)
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sdp_audio_codecs_intersection(r, &codec_filter->remote.audio_codecs, true);
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#if ALLOW_REASSIGNMENT
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/* If osmo-msc were able to trigger a re-assignment after the remote side has picked a codec mismatching the
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* initial Assignment, then this code here would make sense: keep the other codecs as available to choose from,
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* but put the currently assigned codec in the first position. */
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if (sdp_audio_codec_is_set(a)) {
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/* Assignment has completed, the chosen codec should be the first of the resulting SDP.
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* Make sure this is actually listed in the result SDP and move to first place. */
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struct sdp_audio_codec *select = sdp_audio_codec_by_descr(r, a);
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if (!select) {
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/* Not present. Add. */
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if (sdp_audio_codec_by_payload_type(r, a->payload_type, false)) {
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/* Oh crunch, that payload type number is already in use.
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* Find an unused one. */
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for (a->payload_type = 96; a->payload_type <= 127; a->payload_type++) {
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if (!sdp_audio_codec_by_payload_type(r, a->payload_type, false))
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break;
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}
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if (a->payload_type > 127)
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return -ENOSPC;
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}
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select = sdp_audio_codec_add_copy(r, a);
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}
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sdp_audio_codecs_select(r, select);
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}
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#else
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/* Currently, osmo-msc does not trigger re-assignment if the remote side has picked a codec that the local side
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* would also support, but the local side has already assigned a mismatching codec before. Mismatching codecs
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* means call failure. So, currently, if locally, Assignment has already happened, it makes sense to send only
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* the assigned codec as available choice to the remote side. */
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if (sdp_audio_codec_is_set(a)) {
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/* Assignment has completed, the chosen codec should be the the only possible one. */
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struct sdp_audio_codecs assigned_codec = {};
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sdp_audio_codecs_add_copy(&assigned_codec, a);
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sdp_audio_codecs_intersection(r, &assigned_codec, false);
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}
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#endif
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return 0;
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}
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int codec_filter_to_str_buf(char *buf, size_t buflen, const struct codec_filter *codec_filter)
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{
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struct osmo_strbuf sb = { .buf = buf, .len = buflen };
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OSMO_STRBUF_PRINTF(sb, "RAN={");
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OSMO_STRBUF_APPEND(sb, sdp_audio_codecs_to_str_buf, &codec_filter->ran);
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OSMO_STRBUF_PRINTF(sb, "}");
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if (codec_filter->bss.count) {
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OSMO_STRBUF_PRINTF(sb, " bss={");
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OSMO_STRBUF_APPEND(sb, sdp_audio_codecs_to_str_buf, &codec_filter->bss);
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OSMO_STRBUF_PRINTF(sb, "}");
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}
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if (codec_filter->ms.count) {
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OSMO_STRBUF_PRINTF(sb, " MS={");
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OSMO_STRBUF_APPEND(sb, sdp_audio_codecs_to_str_buf, &codec_filter->ms);
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OSMO_STRBUF_PRINTF(sb, "}");
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}
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if (codec_filter->remote.audio_codecs.count
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|| osmo_sockaddr_str_is_nonzero(&codec_filter->remote.rtp)) {
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OSMO_STRBUF_PRINTF(sb, " remote=");
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OSMO_STRBUF_APPEND(sb, sdp_msg_to_str_buf, &codec_filter->remote);
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}
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if (sdp_audio_codec_is_set(&codec_filter->assignment)) {
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OSMO_STRBUF_PRINTF(sb, " assigned=");
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OSMO_STRBUF_APPEND(sb, sdp_audio_codec_to_str_buf, &codec_filter->assignment);
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}
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OSMO_STRBUF_PRINTF(sb, " result=");
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OSMO_STRBUF_APPEND(sb, sdp_msg_to_str_buf, &codec_filter->result);
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return sb.chars_needed;
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}
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char *codec_filter_to_str_c(void *ctx, const struct codec_filter *codec_filter)
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{
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OSMO_NAME_C_IMPL(ctx, 128, "codec_filter_to_str_c-ERROR", codec_filter_to_str_buf, codec_filter)
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}
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const char *codec_filter_to_str(const struct codec_filter *codec_filter)
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{
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return codec_filter_to_str_c(OTC_SELECT, codec_filter);
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}
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