| /* Filter/overlay codec selections for a voice call, across MS, RAN and CN limitations */ |
| /* |
| * (C) 2019-2023 by sysmocom - s.f.m.c. GmbH <info@sysmocom.de> |
| * All Rights Reserved |
| * |
| * Author: Neels Hofmeyr |
| * |
| * SPDX-License-Identifier: AGPL-3.0+ |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU Affero General Public License as published by |
| * the Free Software Foundation; either version 3 of the License, or |
| * (at your option) any later version. |
| * |
| * This program is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| * GNU Affero General Public License for more details. |
| * |
| * You should have received a copy of the GNU Affero General Public License |
| * along with this program. If not, see <http://www.gnu.org/licenses/>. |
| */ |
| |
| #include <osmocom/gsm/protocol/gsm_08_08.h> |
| |
| #include <osmocom/msc/codec_filter.h> |
| #include <osmocom/msc/codec_mapping.h> |
| #include <osmocom/msc/debug.h> |
| |
| /* Add all known payload types encountered in GSM networks */ |
| static void sdp_add_all_geran_codecs(struct sdp_audio_codecs *ac) |
| { |
| /* In order of preference. TODO: make configurable */ |
| static const enum gsm48_bcap_speech_ver mobile_codecs[] = { |
| GSM48_BCAP_SV_AMR_F /*!< 4 GSM FR V3 (FR AMR) */, |
| GSM48_BCAP_SV_AMR_H /*!< 5 GSM HR V3 (HR_AMR) */, |
| GSM48_BCAP_SV_EFR /*!< 2 GSM FR V2 (GSM EFR) */, |
| GSM48_BCAP_SV_FR /*!< 0 GSM FR V1 (GSM FR) */, |
| GSM48_BCAP_SV_HR /*!< 1 GSM HR V1 (GSM HR) */, |
| }; |
| int i; |
| for (i = 0; i < ARRAY_SIZE(mobile_codecs); i++) |
| sdp_audio_codecs_add_speech_ver(ac, mobile_codecs[i]); |
| } |
| |
| /* Add all known AMR payload types encountered in UTRAN networks */ |
| static void sdp_add_all_utran_codecs(struct sdp_audio_codecs *ac) |
| { |
| /* In order of preference. TODO: make configurable */ |
| static const enum gsm48_bcap_speech_ver utran_codecs[] = { |
| GSM48_BCAP_SV_AMR_F /*!< 4 GSM FR V3 (FR AMR) */, |
| GSM48_BCAP_SV_AMR_H /*!< 5 GSM HR V3 (HR_AMR) */, |
| GSM48_BCAP_SV_AMR_OH /*!< 11 GSM HR V6 (OHR AMR) */, |
| GSM48_BCAP_SV_AMR_FW /*!< 8 GSM FR V5 (FR AMR-WB) */, |
| GSM48_BCAP_SV_AMR_OFW /*!< 6 GSM FR V4 (OFR AMR-WB) */, |
| GSM48_BCAP_SV_AMR_OHW /*!< 7 GSM HR V4 (OHR AMR-WB) */, |
| }; |
| int i; |
| for (i = 0; i < ARRAY_SIZE(utran_codecs); i++) |
| sdp_audio_codecs_add_speech_ver(ac, utran_codecs[i]); |
| } |
| |
| void codec_filter_set_ran(struct codec_filter *codec_filter, enum osmo_rat_type ran_type) |
| { |
| codec_filter->ran = (struct sdp_audio_codecs){}; |
| |
| switch (ran_type) { |
| default: |
| case OSMO_RAT_GERAN_A: |
| sdp_add_all_geran_codecs(&codec_filter->ran); |
| break; |
| |
| case OSMO_RAT_UTRAN_IU: |
| sdp_add_all_utran_codecs(&codec_filter->ran); |
| break; |
| } |
| } |
| |
| void codec_filter_set_bss(struct codec_filter *codec_filter, |
| const struct gsm0808_speech_codec_list *codec_list_bss_supported) |
| { |
| codec_filter->bss = (struct sdp_audio_codecs){}; |
| if (codec_list_bss_supported) |
| sdp_audio_codecs_from_speech_codec_list(&codec_filter->bss, codec_list_bss_supported); |
| } |
| |
| /* Render intersections of all known audio codec constraints to reach a resulting choice of favorite audio codec, plus |
| * possible set of alternative audio codecs, in codec_filter->result. (The result.rtp address remains unchanged.) */ |
| int codec_filter_run(struct codec_filter *codec_filter, struct sdp_msg *result, const struct sdp_msg *remote) |
| { |
| struct sdp_audio_codecs *r = &result->audio_codecs; |
| struct sdp_audio_codec *a = &codec_filter->assignment; |
| *r = codec_filter->ran; |
| if (codec_filter->ms.count) |
| sdp_audio_codecs_intersection(r, &codec_filter->ms, false); |
| if (codec_filter->bss.count) |
| sdp_audio_codecs_intersection(r, &codec_filter->bss, false); |
| if (remote->audio_codecs.count) |
| sdp_audio_codecs_intersection(r, &remote->audio_codecs, true); |
| |
| #if 0 |
| /* Future: If osmo-msc were able to trigger a re-assignment after the remote side has picked a codec mismatching |
| * the initial Assignment, then this code here would make sense: keep the other codecs as available to choose |
| * from, but put the currently assigned codec in the first position. So far we only offer the single assigned |
| * codec, because we have no way to deal with the remote side picking a different codec. |
| * Another approach would be to postpone assignment until we know the codecs from the remote side. */ |
| if (sdp_audio_codec_is_set(a)) { |
| /* Assignment has completed, the chosen codec should be the first of the resulting SDP. |
| * Make sure this is actually listed in the result SDP and move to first place. */ |
| struct sdp_audio_codec *select = sdp_audio_codecs_by_descr(r, a); |
| |
| if (!select) { |
| /* Not present. Add. */ |
| if (sdp_audio_codec_by_payload_type(r, a->payload_type, false)) { |
| /* Oh crunch, that payload type number is already in use. |
| * Find an unused one. */ |
| for (a->payload_type = 96; a->payload_type <= 127; a->payload_type++) { |
| if (!sdp_audio_codec_by_payload_type(r, a->payload_type, false)) |
| break; |
| } |
| |
| if (a->payload_type > 127) |
| return -ENOSPC; |
| } |
| select = sdp_audio_codecs_add_copy(r, a); |
| } |
| |
| sdp_audio_codecs_select(r, select); |
| } |
| #else |
| /* Currently, osmo-msc does not trigger re-assignment if the remote side has picked a codec that is different |
| * from the already assigned codec. |
| * So, if locally, Assignment has already chosen a codec, this is the single definitive result to be used |
| * towards the CN. */ |
| if (sdp_audio_codec_is_set(a)) { |
| /* Assignment has completed, the chosen codec should be the the only possible one. */ |
| *r = (struct sdp_audio_codecs){}; |
| sdp_audio_codecs_add_copy(r, a); |
| } |
| #endif |
| return 0; |
| } |
| |
| int codec_filter_to_str_buf(char *buf, size_t buflen, const struct codec_filter *codec_filter, |
| const struct sdp_msg *result, const struct sdp_msg *remote) |
| { |
| struct osmo_strbuf sb = { .buf = buf, .len = buflen }; |
| OSMO_STRBUF_APPEND(sb, sdp_msg_to_str_buf, result); |
| OSMO_STRBUF_PRINTF(sb, " (from:"); |
| |
| if (sdp_audio_codec_is_set(&codec_filter->assignment)) { |
| OSMO_STRBUF_PRINTF(sb, " assigned="); |
| OSMO_STRBUF_APPEND(sb, sdp_audio_codec_to_str_buf, &codec_filter->assignment); |
| } |
| |
| if (remote->audio_codecs.count |
| || osmo_sockaddr_str_is_nonzero(&remote->rtp)) { |
| OSMO_STRBUF_PRINTF(sb, " remote="); |
| OSMO_STRBUF_APPEND(sb, sdp_msg_to_str_buf, remote); |
| } |
| |
| if (codec_filter->ms.count) { |
| OSMO_STRBUF_PRINTF(sb, " MS={"); |
| OSMO_STRBUF_APPEND(sb, sdp_audio_codecs_to_str_buf, &codec_filter->ms); |
| OSMO_STRBUF_PRINTF(sb, "}"); |
| } |
| |
| if (codec_filter->bss.count) { |
| OSMO_STRBUF_PRINTF(sb, " bss={"); |
| OSMO_STRBUF_APPEND(sb, sdp_audio_codecs_to_str_buf, &codec_filter->bss); |
| OSMO_STRBUF_PRINTF(sb, "}"); |
| } |
| |
| OSMO_STRBUF_PRINTF(sb, " RAN={"); |
| OSMO_STRBUF_APPEND(sb, sdp_audio_codecs_to_str_buf, &codec_filter->ran); |
| OSMO_STRBUF_PRINTF(sb, "}"); |
| |
| OSMO_STRBUF_PRINTF(sb, ")"); |
| |
| return sb.chars_needed; |
| } |
| |
| char *codec_filter_to_str_c(void *ctx, const struct codec_filter *codec_filter, const struct sdp_msg *result, |
| const struct sdp_msg *remote) |
| { |
| OSMO_NAME_C_IMPL(ctx, 128, "codec_filter_to_str_c-ERROR", codec_filter_to_str_buf, codec_filter, result, remote) |
| } |
| |
| const char *codec_filter_to_str(const struct codec_filter *codec_filter, const struct sdp_msg *result, |
| const struct sdp_msg *remote) |
| { |
| return codec_filter_to_str_c(OTC_SELECT, codec_filter, result, remote); |
| } |