| /*! \file gsm660.c |
| * GSM 06.60 - GSM EFR Codec. */ |
| /* |
| * (C) 2010 Sylvain Munaut <tnt@246tNt.com> |
| * |
| * All Rights Reserved |
| * |
| * SPDX-License-Identifier: GPL-2.0+ |
| * |
| * This program 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 2 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 General Public License for more details. |
| * |
| */ |
| |
| #include <stdint.h> |
| #include <stdbool.h> |
| |
| #include <osmocom/core/bitvec.h> |
| #include <osmocom/core/utils.h> |
| #include <osmocom/codec/codec.h> |
| |
| /* GSM EFR - subjective importance bit ordering */ |
| /* This array encodes GSM 05.03 Table 6. |
| * |
| * It converts between serial parameter output (as described in |
| * GSM 06.60 Table 6 and GSM 05.03 Table 5) and the order needed |
| * before channel encoding. CRC poly and bit repetition must be |
| * applied prior to this table, as in GSM 05.03 3.1.1, to get 260 |
| * bits from a 244 bits raw EFR frame. |
| */ |
| const uint16_t gsm660_bitorder[260] = { |
| 38, 39, 40, 41, 42, 43, /* 0 -> LTP-LAG 1: b8..b3 */ |
| 145, 146, 147, 148, 149, 150, /* 6 -> LTP-LAG 3: b8..b3 */ |
| 93, 94, /* 12 -> LTP-LAG 2: b5..b4 */ |
| 200, 201, /* 14 -> LTP-LAG 4: b5..b4 */ |
| 47, /* 16 -> LTP-GAIN 1: b3 */ |
| 88, /* 17 -> FCB-GAIN 1: b4 */ |
| 99, /* 18 -> LTP-GAIN 2: b3 */ |
| 140, /* 19 -> FCB-GAIN 2: b4 */ |
| 44, /* 20 -> LTP-LAG 1: b2 */ |
| 151, /* 21 -> LTP-LAG 3: b2 */ |
| 95, /* 22 -> LTP-LAG 2: b3 */ |
| 202, /* 23 -> LTP-LAG 4: b3 */ |
| 1, 2, /* 24 -> LPC 1: b5..b4 */ |
| 7, /* 26 -> LPC 2: b7 */ |
| 9, /* 27 -> LPC 2: b5 */ |
| 17, 18, /* 28 -> LPC 3: b6..b5 */ |
| 23, /* 30 -> LPC 3: b0 */ |
| 45, 46, /* 31 -> LTP-LAG 1: b1..b0 */ |
| 152, 153, /* 33 -> LTP-LAG 3: b1..b0 */ |
| 96, /* 35 -> LTP-LAG 2: b2 */ |
| 203, /* 36 -> LTP-LAG 4: b2 */ |
| 3, 4, /* 37 -> LPC 1: b3..b2 */ |
| 10, 11, /* 39 -> LPC 2: b4..b3 */ |
| 15, /* 41 -> LPC 3: b8 */ |
| 8, /* 42 -> LPC 2: b6 */ |
| 5, 6, /* 43 -> LPC 1: b1..b0 */ |
| 12, /* 45 -> LPC 2: b2 */ |
| 16, /* 46 -> LPC 3: b7 */ |
| 19, /* 47 -> LPC 3: b4 */ |
| 97, /* 48 -> LTP-LAG 2: b1 */ |
| 204, /* 49 -> LTP-LAG 4: b1 */ |
| 0, /* 50 -> LPC 1: b6 */ |
| 13, 14, /* 51 -> LPC 2: b1..b0 */ |
| 20, /* 53 -> LPC 3: b3 */ |
| 24, 25, /* 54 -> LPC 4: b7..b6 */ |
| 27, /* 56 -> LPC 4: b4 */ |
| 154, /* 57 -> LTP-GAIN 3: b3 */ |
| 206, /* 58 -> LTP-GAIN 4: b3 */ |
| 195, /* 59 -> FCB-GAIN 3: b4 */ |
| 247, /* 60 -> FCB-GAIN 4: b4 */ |
| 89, /* 61 -> FCB-GAIN 1: b3 */ |
| 141, /* 62 -> FCB-GAIN 2: b3 */ |
| 196, /* 63 -> FCB-GAIN 3: b3 */ |
| 248, /* 64 -> FCB-GAIN 4: b3 */ |
| 252, 253, 254, 255, 256, 257, 258, 259, /* 65 -> CRC-POLY: b7..b0 */ |
| 48, /* 73 -> LTP-GAIN 1: b2 */ |
| 100, /* 74 -> LTP-GAIN 2: b2 */ |
| 155, /* 75 -> LTP-GAIN 3: b2 */ |
| 207, /* 76 -> LTP-GAIN 4: b2 */ |
| 21, 22, /* 77 -> LPC 3: b2..b1 */ |
| 26, /* 79 -> LPC 4: b5 */ |
| 28, /* 80 -> LPC 4: b3 */ |
| 51, /* 81 -> PULSE 1_1: b3 */ |
| 55, /* 82 -> PULSE 1_2: b3 */ |
| 59, /* 83 -> PULSE 1_3: b3 */ |
| 63, /* 84 -> PULSE 1_4: b3 */ |
| 67, /* 85 -> PULSE 1_5: b3 */ |
| 103, /* 86 -> PULSE 2_1: b3 */ |
| 107, /* 87 -> PULSE 2_2: b3 */ |
| 111, /* 88 -> PULSE 2_3: b3 */ |
| 115, /* 89 -> PULSE 2_4: b3 */ |
| 119, /* 90 -> PULSE 2_5: b3 */ |
| 158, /* 91 -> PULSE 3_1: b3 */ |
| 162, /* 92 -> PULSE 3_2: b3 */ |
| 166, /* 93 -> PULSE 3_3: b3 */ |
| 170, /* 94 -> PULSE 3_4: b3 */ |
| 174, /* 95 -> PULSE 3_5: b3 */ |
| 210, /* 96 -> PULSE 4_1: b3 */ |
| 214, /* 97 -> PULSE 4_2: b3 */ |
| 218, /* 98 -> PULSE 4_3: b3 */ |
| 222, /* 99 -> PULSE 4_4: b3 */ |
| 226, /* 100 -> PULSE 4_5: b3 */ |
| 90, /* 101 -> FCB-GAIN 1: b2 */ |
| 142, /* 102 -> FCB-GAIN 2: b2 */ |
| 197, /* 103 -> FCB-GAIN 3: b2 */ |
| 249, /* 104 -> FCB-GAIN 4: b2 */ |
| 49, /* 105 -> LTP-GAIN 1: b1 */ |
| 101, /* 106 -> LTP-GAIN 2: b1 */ |
| 156, /* 107 -> LTP-GAIN 3: b1 */ |
| 208, /* 108 -> LTP-GAIN 4: b1 */ |
| 29, 30, 31, /* 109 -> LPC 4: b2..b0 */ |
| 32, 33, 34, 35, /* 112 -> LPC 5: b5..b2 */ |
| 98, /* 116 -> LTP-LAG 2: b0 */ |
| 205, /* 117 -> LTP-LAG 4: b0 */ |
| 52, /* 118 -> PULSE 1_1: b2 */ |
| 56, /* 119 -> PULSE 1_2: b2 */ |
| 60, /* 120 -> PULSE 1_3: b2 */ |
| 64, /* 121 -> PULSE 1_4: b2 */ |
| 68, /* 122 -> PULSE 1_5: b2 */ |
| 104, /* 123 -> PULSE 2_1: b2 */ |
| 108, /* 124 -> PULSE 2_2: b2 */ |
| 112, /* 125 -> PULSE 2_3: b2 */ |
| 116, /* 126 -> PULSE 2_4: b2 */ |
| 120, /* 127 -> PULSE 2_5: b2 */ |
| 159, /* 128 -> PULSE 3_1: b2 */ |
| 163, /* 129 -> PULSE 3_2: b2 */ |
| 167, /* 130 -> PULSE 3_3: b2 */ |
| 171, /* 131 -> PULSE 3_4: b2 */ |
| 175, /* 132 -> PULSE 3_5: b2 */ |
| 211, /* 133 -> PULSE 4_1: b2 */ |
| 215, /* 134 -> PULSE 4_2: b2 */ |
| 219, /* 135 -> PULSE 4_3: b2 */ |
| 223, /* 136 -> PULSE 4_4: b2 */ |
| 227, /* 137 -> PULSE 4_5: b2 */ |
| 53, /* 138 -> PULSE 1_1: b1 */ |
| 57, /* 139 -> PULSE 1_2: b1 */ |
| 61, /* 140 -> PULSE 1_3: b1 */ |
| 65, /* 141 -> PULSE 1_4: b1 */ |
| 105, /* 142 -> PULSE 2_1: b1 */ |
| 109, /* 143 -> PULSE 2_2: b1 */ |
| 113, /* 144 -> PULSE 2_3: b1 */ |
| 117, /* 145 -> PULSE 2_4: b1 */ |
| 160, /* 146 -> PULSE 3_1: b1 */ |
| 164, /* 147 -> PULSE 3_2: b1 */ |
| 168, /* 148 -> PULSE 3_3: b1 */ |
| 172, /* 149 -> PULSE 3_4: b1 */ |
| 212, /* 150 -> PULSE 4_1: b1 */ |
| 220, /* 151 -> PULSE 4_3: b1 */ |
| 224, /* 152 -> PULSE 4_4: b1 */ |
| 91, /* 153 -> FCB-GAIN 1: b1 */ |
| 143, /* 154 -> FCB-GAIN 2: b1 */ |
| 198, /* 155 -> FCB-GAIN 3: b1 */ |
| 250, /* 156 -> FCB-GAIN 4: b1 */ |
| 50, /* 157 -> LTP-GAIN 1: b0 */ |
| 102, /* 158 -> LTP-GAIN 2: b0 */ |
| 157, /* 159 -> LTP-GAIN 3: b0 */ |
| 209, /* 160 -> LTP-GAIN 4: b0 */ |
| 92, /* 161 -> FCB-GAIN 1: b0 */ |
| 144, /* 162 -> FCB-GAIN 2: b0 */ |
| 199, /* 163 -> FCB-GAIN 3: b0 */ |
| 251, /* 164 -> FCB-GAIN 4: b0 */ |
| 54, /* 165 -> PULSE 1_1: b0 */ |
| 58, /* 166 -> PULSE 1_2: b0 */ |
| 62, /* 167 -> PULSE 1_3: b0 */ |
| 66, /* 168 -> PULSE 1_4: b0 */ |
| 106, /* 169 -> PULSE 2_1: b0 */ |
| 110, /* 170 -> PULSE 2_2: b0 */ |
| 114, /* 171 -> PULSE 2_3: b0 */ |
| 118, /* 172 -> PULSE 2_4: b0 */ |
| 161, /* 173 -> PULSE 3_1: b0 */ |
| 165, /* 174 -> PULSE 3_2: b0 */ |
| 169, /* 175 -> PULSE 3_3: b0 */ |
| 173, /* 176 -> PULSE 3_4: b0 */ |
| 213, /* 177 -> PULSE 4_1: b0 */ |
| 221, /* 178 -> PULSE 4_3: b0 */ |
| 225, /* 179 -> PULSE 4_4: b0 */ |
| 36, 37, /* 180 -> LPC 5: b1..b0 */ |
| 69, /* 182 -> PULSE 1_5: b1 */ |
| 71, 72, /* 183 -> PULSE 1_5: b1..b1 */ |
| 121, /* 185 -> PULSE 2_5: b1 */ |
| 123, 124, /* 186 -> PULSE 2_5: b1..b1 */ |
| 176, /* 188 -> PULSE 3_5: b1 */ |
| 178, 179, /* 189 -> PULSE 3_5: b1..b1 */ |
| 228, /* 191 -> PULSE 4_5: b1 */ |
| 230, 231, /* 192 -> PULSE 4_5: b1..b1 */ |
| 216, 217, /* 194 -> PULSE 4_2: b1..b0 */ |
| 70, /* 196 -> PULSE 1_5: b0 */ |
| 122, /* 197 -> PULSE 2_5: b0 */ |
| 177, /* 198 -> PULSE 3_5: b0 */ |
| 229, /* 199 -> PULSE 4_5: b0 */ |
| 73, /* 200 -> PULSE 1_6: b2 */ |
| 76, /* 201 -> PULSE 1_7: b2 */ |
| 79, /* 202 -> PULSE 1_8: b2 */ |
| 82, /* 203 -> PULSE 1_9: b2 */ |
| 85, /* 204 -> PULSE 1_10: b2 */ |
| 125, /* 205 -> PULSE 2_6: b2 */ |
| 128, /* 206 -> PULSE 2_7: b2 */ |
| 131, /* 207 -> PULSE 2_8: b2 */ |
| 134, /* 208 -> PULSE 2_9: b2 */ |
| 137, /* 209 -> PULSE 2_10: b2 */ |
| 180, /* 210 -> PULSE 3_6: b2 */ |
| 183, /* 211 -> PULSE 3_7: b2 */ |
| 186, /* 212 -> PULSE 3_8: b2 */ |
| 189, /* 213 -> PULSE 3_9: b2 */ |
| 192, /* 214 -> PULSE 3_10: b2 */ |
| 232, /* 215 -> PULSE 4_6: b2 */ |
| 235, /* 216 -> PULSE 4_7: b2 */ |
| 238, /* 217 -> PULSE 4_8: b2 */ |
| 241, /* 218 -> PULSE 4_9: b2 */ |
| 244, /* 219 -> PULSE 4_10: b2 */ |
| 74, /* 220 -> PULSE 1_6: b1 */ |
| 77, /* 221 -> PULSE 1_7: b1 */ |
| 80, /* 222 -> PULSE 1_8: b1 */ |
| 83, /* 223 -> PULSE 1_9: b1 */ |
| 86, /* 224 -> PULSE 1_10: b1 */ |
| 126, /* 225 -> PULSE 2_6: b1 */ |
| 129, /* 226 -> PULSE 2_7: b1 */ |
| 132, /* 227 -> PULSE 2_8: b1 */ |
| 135, /* 228 -> PULSE 2_9: b1 */ |
| 138, /* 229 -> PULSE 2_10: b1 */ |
| 181, /* 230 -> PULSE 3_6: b1 */ |
| 184, /* 231 -> PULSE 3_7: b1 */ |
| 187, /* 232 -> PULSE 3_8: b1 */ |
| 190, /* 233 -> PULSE 3_9: b1 */ |
| 193, /* 234 -> PULSE 3_10: b1 */ |
| 233, /* 235 -> PULSE 4_6: b1 */ |
| 236, /* 236 -> PULSE 4_7: b1 */ |
| 239, /* 237 -> PULSE 4_8: b1 */ |
| 242, /* 238 -> PULSE 4_9: b1 */ |
| 245, /* 239 -> PULSE 4_10: b1 */ |
| 75, /* 240 -> PULSE 1_6: b0 */ |
| 78, /* 241 -> PULSE 1_7: b0 */ |
| 81, /* 242 -> PULSE 1_8: b0 */ |
| 84, /* 243 -> PULSE 1_9: b0 */ |
| 87, /* 244 -> PULSE 1_10: b0 */ |
| 127, /* 245 -> PULSE 2_6: b0 */ |
| 130, /* 246 -> PULSE 2_7: b0 */ |
| 133, /* 247 -> PULSE 2_8: b0 */ |
| 136, /* 248 -> PULSE 2_9: b0 */ |
| 139, /* 249 -> PULSE 2_10: b0 */ |
| 182, /* 250 -> PULSE 3_6: b0 */ |
| 185, /* 251 -> PULSE 3_7: b0 */ |
| 188, /* 252 -> PULSE 3_8: b0 */ |
| 191, /* 253 -> PULSE 3_9: b0 */ |
| 194, /* 254 -> PULSE 3_10: b0 */ |
| 234, /* 255 -> PULSE 4_6: b0 */ |
| 237, /* 256 -> PULSE 4_7: b0 */ |
| 240, /* 257 -> PULSE 4_8: b0 */ |
| 243, /* 258 -> PULSE 4_9: b0 */ |
| 246, /* 259 -> PULSE 4_10: b0 */ |
| }; |
| |
| static const uint8_t sid_code_word_bits[95] = { |
| /* bit numbers are relative to "pure" EFR frame beginning, |
| * not counting the signature bits. */ |
| 45, 46, 48, 49, 50, 51, 52, 53, 54, 55, |
| 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, |
| 66, 67, 68, 94, 95, 96, 98, 99, 100, 101, |
| 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, |
| 112, 113, 114, 115, 116, 117, 118, 148, 149, 150, |
| 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, |
| 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, |
| 171, 196, 197, 198, 199, 200, 201, 202, 203, 204, |
| 205, 206, 207, 208, 209, 212, 213, 214, 215, 216, |
| 217, 218, 219, 220, 221 |
| }; |
| |
| /*! Check whether RTP frame contains EFR SID code word according to |
| * TS 101 318 §5.3.2 |
| * \param[in] rtp_payload Buffer with RTP payload |
| * \param[in] payload_len Length of payload |
| * \returns true if code word is found, false otherwise |
| */ |
| bool osmo_efr_check_sid(const uint8_t *rtp_payload, size_t payload_len) |
| { |
| struct bitvec bv; |
| uint16_t i; |
| |
| /* signature does not match Enhanced Full Rate SID */ |
| if ((rtp_payload[0] >> 4) != 0xC) |
| return false; |
| |
| bv.data = (uint8_t *) rtp_payload; |
| bv.data_len = payload_len; |
| |
| /* code word is all 1 at given bits */ |
| for (i = 0; i < ARRAY_SIZE(sid_code_word_bits); i++) { |
| if (bitvec_get_bit_pos(&bv, sid_code_word_bits[i]+4) != ONE) |
| return false; |
| } |
| |
| return true; |
| } |
| |
| /*! Classify potentially-SID EFR codec frame in RTP format according |
| * to the rules of GSM 06.81 §6.1.1 |
| * \param[in] rtp_payload Buffer with RTP payload |
| * \returns enum osmo_gsm631_sid_class, with symbolic values |
| * OSMO_GSM631_SID_CLASS_SPEECH, OSMO_GSM631_SID_CLASS_INVALID or |
| * OSMO_GSM631_SID_CLASS_VALID corresponding to the 3 possible bit-counting |
| * classifications prescribed by the spec. |
| * |
| * Differences between the more familiar osmo_efr_check_sid() and the present |
| * function are: |
| * |
| * 1. osmo_efr_check_sid() returns true only if the SID frame is absolutely |
| * perfect, with all 95 bits of the SID code word set. However, the |
| * rules of GSM 06.81 §6.1.1 allow up to one bit to be in error, |
| * and the frame is still accepted as valid SID. |
| * |
| * 2. The third possible state of invalid SID is not handled at all by the |
| * simpler osmo_efr_check_sid() function. |
| * |
| * 3. osmo_efr_check_sid() includes a check for 0xC RTP signature, and returns |
| * false if that signature nibble is wrong. That check is not included |
| * in the present version because there is no place for it in the |
| * ETSI-prescribed classification, it is neither speech nor SID. The |
| * assumption is that this function is used to classify the bit content |
| * of received codec frames, not their RTP encoding - the latter needs |
| * to be validated beforehand. |
| * |
| * Which function should one use? The answer depends on the specific |
| * circumstances, and needs to be addressed on a case-by-case basis. |
| */ |
| enum osmo_gsm631_sid_class osmo_efr_sid_classify(const uint8_t *rtp_payload) |
| { |
| struct bitvec bv; |
| uint16_t i, n; |
| |
| bv.data = (uint8_t *) rtp_payload; |
| bv.data_len = GSM_EFR_BYTES; |
| |
| /* count not-SID-matching bits per the spec */ |
| n = 0; |
| for (i = 0; i < ARRAY_SIZE(sid_code_word_bits); i++) { |
| if (bitvec_get_bit_pos(&bv, sid_code_word_bits[i]+4) != ONE) |
| n++; |
| if (n >= 16) |
| return OSMO_GSM631_SID_CLASS_SPEECH; |
| } |
| if (n >= 2) |
| return OSMO_GSM631_SID_CLASS_INVALID; |
| else |
| return OSMO_GSM631_SID_CLASS_VALID; |
| } |
| |
| /*! Reset the SID field of a potentially corrupted, but still valid GSM-EFR |
| * SID frame in RTP encoding to its pristine state (full SID code word). |
| * \param[in] rtp_payload Buffer with RTP payload - must be writable! |
| * |
| * Per GSM 06.62 section 5.3, a freshly minted SID frame consists of 58 bits |
| * of comfort noise parameters (LSF and 4 times fixed codebook gain), 95 bits |
| * of SID code word (all 1s) and 91 unused bits (all 0s). Network elements |
| * that receive SID frames from call leg A uplink and need to retransmit them |
| * on leg B downlink should "rejuvenate" received SID frames prior to |
| * retransmission by resetting the SID field to its pristine state of all 1s; |
| * this function does the job. |
| * |
| * Potential TODO: it would be nice to also zero out the remaining 91 bits |
| * which the spec leaves as reserved, clearing out leg A radio bit errors - |
| * but do we really need to? |
| */ |
| void osmo_efr_sid_reset(uint8_t *rtp_payload) |
| { |
| /* set all 95 SID code word bits to 1 */ |
| rtp_payload[6] |= 0x6F; |
| rtp_payload[7] = 0xFF; |
| rtp_payload[8] = 0xFF; |
| rtp_payload[9] |= 0x80; |
| rtp_payload[12] |= 0x3B; |
| rtp_payload[13] = 0xFF; |
| rtp_payload[14] = 0xFF; |
| rtp_payload[15] |= 0xE0; |
| rtp_payload[19] = 0xFF; |
| rtp_payload[20] = 0xFF; |
| rtp_payload[21] = 0xFF; |
| rtp_payload[25] = 0xFF; |
| rtp_payload[26] |= 0xFC; |
| rtp_payload[27] = 0xFF; |
| rtp_payload[28] |= 0xC0; |
| } |
| |
| /*! Preen potentially-SID EFR codec frame in RTP format, ensuring that it is |
| * either a speech frame or a valid SID, and if the latter, making it a |
| * perfect, error-free SID frame. |
| * \param[in] rtp_payload Buffer with RTP payload - must be writable! |
| * \returns true if the frame is good, false otherwise |
| */ |
| bool osmo_efr_sid_preen(uint8_t *rtp_payload) |
| { |
| enum osmo_gsm631_sid_class sidc; |
| |
| sidc = osmo_efr_sid_classify(rtp_payload); |
| switch (sidc) { |
| case OSMO_GSM631_SID_CLASS_SPEECH: |
| return true; |
| case OSMO_GSM631_SID_CLASS_INVALID: |
| return false; |
| case OSMO_GSM631_SID_CLASS_VALID: |
| /* "Rejuvenate" this SID frame, correcting any errors */ |
| osmo_efr_sid_reset(rtp_payload); |
| return true; |
| default: |
| /* There are only 3 possible SID classifications per GSM 06.81 |
| * section 6.1.1, thus any other return value is a grave error |
| * in the code. */ |
| OSMO_ASSERT(0); |
| } |
| } |