| /* EFR RTP Payload according to RFC3551. Only one codec frame per RTP */ |
| /* (C) 2017 by Harald Welte <laforge@gnumonks.org> */ |
| |
| /* |
| * This file is part of gapk (GSM Audio Pocket Knife). |
| * |
| * gapk is free software: you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License as published by |
| * the Free Software Foundation, either version 3 of the License, or |
| * (at your option) any later version. |
| * |
| * gapk 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 General Public License for more details. |
| * |
| * You should have received a copy of the GNU General Public License |
| * along with gapk. If not, see <http://www.gnu.org/licenses/>. |
| */ |
| |
| #include <stdint.h> |
| #include <assert.h> |
| |
| #include <osmocom/codec/codec.h> |
| |
| #include <gapk/codecs.h> |
| #include <gapk/formats.h> |
| #include <gapk/utils.h> |
| |
| #define EFR_LEN 31 |
| #define EFR_MAGIC 0xc |
| |
| /* conversion function: RTP payload -> canonical format */ |
| static int |
| rtp_efr_from_canon(uint8_t *dst, const uint8_t *src, unsigned int src_len) |
| { |
| int i; |
| |
| /* according to RFC3551 4.5.9 */ |
| assert(src_len == EFR_CANON_LEN); |
| |
| dst[0] = (EFR_MAGIC << 4) | (src[0] >> 4); |
| for (i=1; i<EFR_LEN; i++) |
| dst[i] = (src[i-1] << 4) | (src[i] >> 4); |
| |
| return EFR_LEN; |
| } |
| |
| /* conversion function: canonical format -> RTP payload */ |
| static int |
| rtp_efr_to_canon(uint8_t *dst, const uint8_t *src, unsigned int src_len) |
| { |
| int i; |
| |
| assert(src_len == EFR_LEN); |
| |
| for (i=0; i<(EFR_LEN-1); i++) |
| dst[i] = (src[i] << 4) | (src[i+1] >> 4); |
| dst[EFR_LEN-1] = src[EFR_LEN-1] << 4; |
| |
| return EFR_CANON_LEN; |
| } |
| |
| const struct format_desc fmt_rtp_efr = { |
| .type = FMT_RTP_EFR, |
| .codec_type = CODEC_EFR, |
| .name = "rtp-efr", |
| .description = "RTP payload for EFR according to RFC3551", |
| |
| .frame_len = EFR_LEN, |
| .conv_from_canon = rtp_efr_from_canon, |
| .conv_to_canon = rtp_efr_to_canon, |
| }; |