annotate libgsmefr/bfi_nodata.c @ 242:f081a6850fb5

libgsmfrp: new refined implementation The previous implementation exhibited the following defects, which are now fixed: 1) The last received valid SID was cached forever for the purpose of handling future invalid SIDs - we could have received some valid SID ages ago, then lots of speech or NO_DATA, and if we then get an invalid SID, we would resurrect the last valid SID from ancient history - a bad design. In our new design, we handle invalid SID based on the current state, much like BFI. 2) GSM 06.11 spec says clearly that after the second lost SID (received BFI=1 && TAF=1 in CN state) we need to gradually decrease the output level, rather than jump directly to emitting silence frames - we previously failed to implement such logic. 3) Per GSM 06.12 section 5.2, Xmaxc should be the same in all 4 subframes in a SID frame. What should we do if we receive an otherwise valid SID frame with different Xmaxc? Our previous approach would replicate this Xmaxc oddity in every subsequent generated CN frame, which is rather bad. In our new design, the very first CN frame (which can be seen as a transformation of the SID frame itself) retains the original 4 distinct Xmaxc, but all subsequent CN frames are based on the Xmaxc from the last subframe of the most recent SID.
author Mychaela Falconia <falcon@freecalypso.org>
date Tue, 09 May 2023 05:16:31 +0000
parents 452c1d5a6268
children
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
99
7152cc7d1ca3 libgsmefr: implement EFR_decode_bfi_nodata()
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
1 /*
7152cc7d1ca3 libgsmefr: implement EFR_decode_bfi_nodata()
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
2 * In the expected usage mode of our libgsmefr decoder as part of "soft TRAU"
7152cc7d1ca3 libgsmefr: implement EFR_decode_bfi_nodata()
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
3 * uplink implementation, there will be times when the radio subsystem tells
7152cc7d1ca3 libgsmefr: implement EFR_decode_bfi_nodata()
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
4 * us that a frame has been lost, but we don't have any errored bits to feed
160
eefef9f6d533 libgsmefr: randomize d1035pf params in no-data BFI case
Mychaela Falconia <falcon@freecalypso.org>
parents: 99
diff changeset
5 * to the decoder as ETSI canon calls for. Specifically, the canonical EFR
eefef9f6d533 libgsmefr: randomize d1035pf params in no-data BFI case
Mychaela Falconia <falcon@freecalypso.org>
parents: 99
diff changeset
6 * decoder will use the "fixed codebook excitation pulses" part of errored
eefef9f6d533 libgsmefr: randomize d1035pf params in no-data BFI case
Mychaela Falconia <falcon@freecalypso.org>
parents: 99
diff changeset
7 * frames when a BFI comes in after speech, although not when BFI comes in
eefef9f6d533 libgsmefr: randomize d1035pf params in no-data BFI case
Mychaela Falconia <falcon@freecalypso.org>
parents: 99
diff changeset
8 * after SID. Our solution in EFR_decode_bfi_nodata(): we look in the
eefef9f6d533 libgsmefr: randomize d1035pf params in no-data BFI case
Mychaela Falconia <falcon@freecalypso.org>
parents: 99
diff changeset
9 * decoder state to see if we are in speech mode, and if we are, we fill
eefef9f6d533 libgsmefr: randomize d1035pf params in no-data BFI case
Mychaela Falconia <falcon@freecalypso.org>
parents: 99
diff changeset
10 * the needed parameters with a PRNG.
99
7152cc7d1ca3 libgsmefr: implement EFR_decode_bfi_nodata()
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
11 */
7152cc7d1ca3 libgsmefr: implement EFR_decode_bfi_nodata()
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
12
7152cc7d1ca3 libgsmefr: implement EFR_decode_bfi_nodata()
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
13 #include <string.h>
7152cc7d1ca3 libgsmefr: implement EFR_decode_bfi_nodata()
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
14 #include "gsm_efr.h"
160
eefef9f6d533 libgsmefr: randomize d1035pf params in no-data BFI case
Mychaela Falconia <falcon@freecalypso.org>
parents: 99
diff changeset
15 #include "typedef.h"
eefef9f6d533 libgsmefr: randomize d1035pf params in no-data BFI case
Mychaela Falconia <falcon@freecalypso.org>
parents: 99
diff changeset
16 #include "namespace.h"
eefef9f6d533 libgsmefr: randomize d1035pf params in no-data BFI case
Mychaela Falconia <falcon@freecalypso.org>
parents: 99
diff changeset
17 #include "cnst.h"
eefef9f6d533 libgsmefr: randomize d1035pf params in no-data BFI case
Mychaela Falconia <falcon@freecalypso.org>
parents: 99
diff changeset
18 #include "dtx.h"
eefef9f6d533 libgsmefr: randomize d1035pf params in no-data BFI case
Mychaela Falconia <falcon@freecalypso.org>
parents: 99
diff changeset
19 #include "dec_state.h"
eefef9f6d533 libgsmefr: randomize d1035pf params in no-data BFI case
Mychaela Falconia <falcon@freecalypso.org>
parents: 99
diff changeset
20
eefef9f6d533 libgsmefr: randomize d1035pf params in no-data BFI case
Mychaela Falconia <falcon@freecalypso.org>
parents: 99
diff changeset
21 static void random_1035(Word32 *lfsr, Word16 *param_1035)
eefef9f6d533 libgsmefr: randomize d1035pf params in no-data BFI case
Mychaela Falconia <falcon@freecalypso.org>
parents: 99
diff changeset
22 {
eefef9f6d533 libgsmefr: randomize d1035pf params in no-data BFI case
Mychaela Falconia <falcon@freecalypso.org>
parents: 99
diff changeset
23 Word16 *p = param_1035;
eefef9f6d533 libgsmefr: randomize d1035pf params in no-data BFI case
Mychaela Falconia <falcon@freecalypso.org>
parents: 99
diff changeset
24 Word16 i;
eefef9f6d533 libgsmefr: randomize d1035pf params in no-data BFI case
Mychaela Falconia <falcon@freecalypso.org>
parents: 99
diff changeset
25
eefef9f6d533 libgsmefr: randomize d1035pf params in no-data BFI case
Mychaela Falconia <falcon@freecalypso.org>
parents: 99
diff changeset
26 /* 5 params of bit width 4 */
eefef9f6d533 libgsmefr: randomize d1035pf params in no-data BFI case
Mychaela Falconia <falcon@freecalypso.org>
parents: 99
diff changeset
27 for (i = 0; i < 5; i++)
eefef9f6d533 libgsmefr: randomize d1035pf params in no-data BFI case
Mychaela Falconia <falcon@freecalypso.org>
parents: 99
diff changeset
28 *p++ = pseudonoise(lfsr, 4);
eefef9f6d533 libgsmefr: randomize d1035pf params in no-data BFI case
Mychaela Falconia <falcon@freecalypso.org>
parents: 99
diff changeset
29 /* another 5 params of bit width 3 */
eefef9f6d533 libgsmefr: randomize d1035pf params in no-data BFI case
Mychaela Falconia <falcon@freecalypso.org>
parents: 99
diff changeset
30 for (i = 0; i < 5; i++)
eefef9f6d533 libgsmefr: randomize d1035pf params in no-data BFI case
Mychaela Falconia <falcon@freecalypso.org>
parents: 99
diff changeset
31 *p++ = pseudonoise(lfsr, 3);
eefef9f6d533 libgsmefr: randomize d1035pf params in no-data BFI case
Mychaela Falconia <falcon@freecalypso.org>
parents: 99
diff changeset
32 }
eefef9f6d533 libgsmefr: randomize d1035pf params in no-data BFI case
Mychaela Falconia <falcon@freecalypso.org>
parents: 99
diff changeset
33
eefef9f6d533 libgsmefr: randomize d1035pf params in no-data BFI case
Mychaela Falconia <falcon@freecalypso.org>
parents: 99
diff changeset
34 static void random_bad_frame(struct EFR_decoder_state *st, Word16 *params)
eefef9f6d533 libgsmefr: randomize d1035pf params in no-data BFI case
Mychaela Falconia <falcon@freecalypso.org>
parents: 99
diff changeset
35 {
eefef9f6d533 libgsmefr: randomize d1035pf params in no-data BFI case
Mychaela Falconia <falcon@freecalypso.org>
parents: 99
diff changeset
36 Word32 *lfsr = &st->L_pn_seed_nodata;
eefef9f6d533 libgsmefr: randomize d1035pf params in no-data BFI case
Mychaela Falconia <falcon@freecalypso.org>
parents: 99
diff changeset
37
eefef9f6d533 libgsmefr: randomize d1035pf params in no-data BFI case
Mychaela Falconia <falcon@freecalypso.org>
parents: 99
diff changeset
38 random_1035(lfsr, params + 7);
eefef9f6d533 libgsmefr: randomize d1035pf params in no-data BFI case
Mychaela Falconia <falcon@freecalypso.org>
parents: 99
diff changeset
39 random_1035(lfsr, params + 20);
eefef9f6d533 libgsmefr: randomize d1035pf params in no-data BFI case
Mychaela Falconia <falcon@freecalypso.org>
parents: 99
diff changeset
40 random_1035(lfsr, params + 33);
eefef9f6d533 libgsmefr: randomize d1035pf params in no-data BFI case
Mychaela Falconia <falcon@freecalypso.org>
parents: 99
diff changeset
41 random_1035(lfsr, params + 46);
eefef9f6d533 libgsmefr: randomize d1035pf params in no-data BFI case
Mychaela Falconia <falcon@freecalypso.org>
parents: 99
diff changeset
42 }
99
7152cc7d1ca3 libgsmefr: implement EFR_decode_bfi_nodata()
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
43
7152cc7d1ca3 libgsmefr: implement EFR_decode_bfi_nodata()
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
44 void EFR_decode_bfi_nodata(struct EFR_decoder_state *st, int taf,
7152cc7d1ca3 libgsmefr: implement EFR_decode_bfi_nodata()
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
45 int16_t *pcm_out)
7152cc7d1ca3 libgsmefr: implement EFR_decode_bfi_nodata()
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
46 {
7152cc7d1ca3 libgsmefr: implement EFR_decode_bfi_nodata()
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
47 int16_t params[EFR_NUM_PARAMS];
7152cc7d1ca3 libgsmefr: implement EFR_decode_bfi_nodata()
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
48
183
452c1d5a6268 libgsmefr BFI w/o data: emit zero output after decoder reset
Mychaela Falconia <falcon@freecalypso.org>
parents: 160
diff changeset
49 if (st->reset_flag_old) {
452c1d5a6268 libgsmefr BFI w/o data: emit zero output after decoder reset
Mychaela Falconia <falcon@freecalypso.org>
parents: 160
diff changeset
50 memset(pcm_out, 0, sizeof(int16_t) * L_FRAME);
452c1d5a6268 libgsmefr BFI w/o data: emit zero output after decoder reset
Mychaela Falconia <falcon@freecalypso.org>
parents: 160
diff changeset
51 return;
452c1d5a6268 libgsmefr BFI w/o data: emit zero output after decoder reset
Mychaela Falconia <falcon@freecalypso.org>
parents: 160
diff changeset
52 }
99
7152cc7d1ca3 libgsmefr: implement EFR_decode_bfi_nodata()
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
53 memset(params, 0, sizeof(int16_t) * EFR_NUM_PARAMS);
160
eefef9f6d533 libgsmefr: randomize d1035pf params in no-data BFI case
Mychaela Falconia <falcon@freecalypso.org>
parents: 99
diff changeset
54 if (st->rxdtx_ctrl & RX_SP_FLAG)
eefef9f6d533 libgsmefr: randomize d1035pf params in no-data BFI case
Mychaela Falconia <falcon@freecalypso.org>
parents: 99
diff changeset
55 random_bad_frame(st, params);
99
7152cc7d1ca3 libgsmefr: implement EFR_decode_bfi_nodata()
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
56 EFR_decode_params(st, params, 1, 0, taf, pcm_out);
7152cc7d1ca3 libgsmefr: implement EFR_decode_bfi_nodata()
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
57 }