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libgsmefr/dtx.c: initial import from ETSI code
author Mychaela Falconia <falcon@freecalypso.org>
date Sat, 26 Nov 2022 03:52:39 +0000
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children 58b64224d4ac
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65:cb080ec1817e 66:824ff833bda9
1 /***************************************************************************
2 *
3 * File Name: dtx.c
4 *
5 * Purpose: Contains functions for performing DTX operation and comfort
6 * noise generation.
7 *
8 * Below is a listing of all the functions appearing in the file.
9 * The functions are arranged according to their purpose. Under
10 * each heading, the ordering is hierarchical.
11 *
12 * Resetting of static variables of TX DTX:
13 * reset_tx_dtx()
14 * Resetting of static variables of RX DTX:
15 * reset_rx_dtx()
16 *
17 * TX DTX handler (called by the speech encoder):
18 * tx_dtx()
19 * RX DTX handler (called by the speech decoder):
20 * rx_dtx()
21 * Encoding of comfort noise parameters into SID frame:
22 * CN_encoding()
23 * Encoding of SID codeword into SID frame:
24 * sid_codeword_encoding()
25 * Detecting of SID codeword from a frame:
26 * sid_frame_detection()
27 * Update the LSF parameter history:
28 * update_lsf_history()
29 * Update the reference LSF parameter vector:
30 * update_lsf_p_CN()
31 * Compute the averaged LSF parameter vector:
32 * aver_lsf_history()
33 * Update the fixed codebook gain parameter history of the encoder:
34 * update_gain_code_history_tx()
35 * Update the fixed codebook gain parameter history of the decoder:
36 * update_gain_code_history_rx()
37 * Compute the unquantized fixed codebook gain:
38 * compute_CN_excitation_gain()
39 * Update the reference fixed codebook gain:
40 * update_gcode0_CN()
41 * Compute the averaged fixed codebook gain:
42 * aver_gain_code_history()
43 * Compute the comfort noise fixed codebook excitation:
44 * build_CN_code()
45 * Generate a random integer value:
46 * pseudonoise()
47 * Interpolate a comfort noise parameter value over the comfort noise
48 * update period:
49 * interpolate_CN_param()
50 * Interpolate comfort noise LSF pparameter values over the comfort
51 * noise update period:
52 * interpolate_CN_lsf()
53 * interpolate_CN_param()
54 *
55 **************************************************************************/
56
57 #include "typedef.h"
58 #include "basic_op.h"
59 #include "cnst.h"
60 #include "sig_proc.h"
61 #include "count.h"
62 #include "dtx.h"
63
64 /* Inverse values of DTX hangover period and DTX hangover period + 1 */
65
66 #define INV_DTX_HANGOVER (0x7fff / DTX_HANGOVER)
67 #define INV_DTX_HANGOVER_P1 (0x7fff / (DTX_HANGOVER+1))
68
69 #define NB_PULSE 10 /* Number of pulses in fixed codebook excitation */
70
71 /* SID frame classification thresholds */
72
73 #define VALID_SID_THRESH 2
74 #define INVALID_SID_THRESH 16
75
76 /* Constant DTX_ELAPSED_THRESHOLD is used as threshold for allowing
77 SID frame updating without hangover period in case when elapsed
78 time measured from previous SID update is below 24 */
79
80 #define DTX_ELAPSED_THRESHOLD (24 + DTX_HANGOVER - 1)
81
82 /* Index map for encoding and detecting SID codeword */
83
84 static const Word16 SID_codeword_bit_idx[95] =
85 {
86 45, 46, 48, 49, 50, 51, 52, 53, 54, 55,
87 56, 57, 58, 59, 60, 61, 62, 63, 64, 65,
88 66, 67, 68, 94, 95, 96, 98, 99, 100, 101,
89 102, 103, 104, 105, 106, 107, 108, 109, 110, 111,
90 112, 113, 114, 115, 116, 117, 118, 148, 149, 150,
91 151, 152, 153, 154, 155, 156, 157, 158, 159, 160,
92 161, 162, 163, 164, 165, 166, 167, 168, 169, 170,
93 171, 196, 197, 198, 199, 200, 201, 202, 203, 204,
94 205, 206, 207, 208, 209, 212, 213, 214, 215, 216,
95 217, 218, 219, 220, 221
96 };
97
98 Word16 txdtx_ctrl; /* Encoder DTX control word */
99 Word16 rxdtx_ctrl; /* Decoder DTX control word */
100 Word16 CN_excitation_gain; /* Unquantized fixed codebook gain */
101 Word32 L_pn_seed_tx; /* PN generator seed (encoder) */
102 Word32 L_pn_seed_rx; /* PN generator seed (decoder) */
103 Word16 rx_dtx_state; /* State of comfort noise insertion period */
104
105 static Word16 txdtx_hangover; /* Length of hangover period (VAD=0, SP=1) */
106 static Word16 rxdtx_aver_period;/* Length of hangover period (VAD=0, SP=1) */
107 static Word16 txdtx_N_elapsed; /* Measured time from previous SID frame */
108 static Word16 rxdtx_N_elapsed; /* Measured time from previous SID frame */
109 static Word16 old_CN_mem_tx[6]; /* The most recent CN parameters are stored*/
110 static Word16 prev_SID_frames_lost; /* Counter for lost SID frames */
111 static Word16 buf_p_tx; /* Circular buffer pointer for gain code
112 history update in tx */
113 static Word16 buf_p_rx; /* Circular buffer pointer for gain code
114 history update in rx */
115
116 Word16 lsf_old_tx[DTX_HANGOVER][M]; /* Comfort noise LSF averaging buffer */
117 Word16 lsf_old_rx[DTX_HANGOVER][M]; /* Comfort noise LSF averaging buffer */
118
119 Word16 gain_code_old_tx[4 * DTX_HANGOVER]; /* Comfort noise gain averaging
120 buffer */
121 Word16 gain_code_old_rx[4 * DTX_HANGOVER]; /* Comfort noise gain averaging
122 buffer */
123
124 /*************************************************************************
125 *
126 * FUNCTION NAME: reset_tx_dtx
127 *
128 * PURPOSE: Resets the static variables of the TX DTX handler to their
129 * initial values
130 *
131 *************************************************************************/
132
133 void reset_tx_dtx ()
134 {
135 Word16 i;
136
137 /* suppose infinitely long speech period before start */
138
139 txdtx_hangover = DTX_HANGOVER;
140 txdtx_N_elapsed = 0x7fff;
141 txdtx_ctrl = TX_SP_FLAG | TX_VAD_FLAG;
142
143 for (i = 0; i < 6; i++)
144 {
145 old_CN_mem_tx[i] = 0;
146 }
147
148 for (i = 0; i < DTX_HANGOVER; i++)
149 {
150 lsf_old_tx[i][0] = 1384;
151 lsf_old_tx[i][1] = 2077;
152 lsf_old_tx[i][2] = 3420;
153 lsf_old_tx[i][3] = 5108;
154 lsf_old_tx[i][4] = 6742;
155 lsf_old_tx[i][5] = 8122;
156 lsf_old_tx[i][6] = 9863;
157 lsf_old_tx[i][7] = 11092;
158 lsf_old_tx[i][8] = 12714;
159 lsf_old_tx[i][9] = 13701;
160 }
161
162 for (i = 0; i < 4 * DTX_HANGOVER; i++)
163 {
164 gain_code_old_tx[i] = 0;
165 }
166
167 L_pn_seed_tx = PN_INITIAL_SEED;
168
169 buf_p_tx = 0;
170 return;
171 }
172
173 /*************************************************************************
174 *
175 * FUNCTION NAME: reset_rx_dtx
176 *
177 * PURPOSE: Resets the static variables of the RX DTX handler to their
178 * initial values
179 *
180 *************************************************************************/
181
182 void reset_rx_dtx ()
183 {
184 Word16 i;
185
186 /* suppose infinitely long speech period before start */
187
188 rxdtx_aver_period = DTX_HANGOVER;
189 rxdtx_N_elapsed = 0x7fff;
190 rxdtx_ctrl = RX_SP_FLAG;
191
192 for (i = 0; i < DTX_HANGOVER; i++)
193 {
194 lsf_old_rx[i][0] = 1384;
195 lsf_old_rx[i][1] = 2077;
196 lsf_old_rx[i][2] = 3420;
197 lsf_old_rx[i][3] = 5108;
198 lsf_old_rx[i][4] = 6742;
199 lsf_old_rx[i][5] = 8122;
200 lsf_old_rx[i][6] = 9863;
201 lsf_old_rx[i][7] = 11092;
202 lsf_old_rx[i][8] = 12714;
203 lsf_old_rx[i][9] = 13701;
204 }
205
206 for (i = 0; i < 4 * DTX_HANGOVER; i++)
207 {
208 gain_code_old_rx[i] = 0;
209 }
210
211 L_pn_seed_rx = PN_INITIAL_SEED;
212 rx_dtx_state = CN_INT_PERIOD - 1;
213
214 prev_SID_frames_lost = 0;
215 buf_p_rx = 0;
216
217 return;
218 }
219
220 /*************************************************************************
221 *
222 * FUNCTION NAME: tx_dtx
223 *
224 * PURPOSE: DTX handler of the speech encoder. Determines when to add
225 * the hangover period to the end of the speech burst, and
226 * also determines when to use old SID parameters, and when
227 * to update the SID parameters. This function also initializes
228 * the pseudo noise generator shift register.
229 *
230 * Operation of the TX DTX handler is based on the VAD flag
231 * given as input from the speech encoder.
232 *
233 * INPUTS: VAD_flag Voice activity decision
234 * *txdtx_ctrl Old encoder DTX control word
235 *
236 * OUTPUTS: *txdtx_ctrl Updated encoder DTX control word
237 * L_pn_seed_tx Initialized pseudo noise generator shift
238 * register (global variable)
239 *
240 * RETURN VALUE: none
241 *
242 *************************************************************************/
243
244 void tx_dtx (
245 Word16 VAD_flag,
246 Word16 *txdtx_ctrl
247 )
248 {
249
250 /* N_elapsed (frames since last SID update) is incremented. If SID
251 is updated N_elapsed is cleared later in this function */
252
253 txdtx_N_elapsed = add (txdtx_N_elapsed, 1);
254
255 /* If voice activity was detected, reset hangover counter */
256
257 test ();
258 if (sub (VAD_flag, 1) == 0)
259 {
260 txdtx_hangover = DTX_HANGOVER; move16 ();
261 *txdtx_ctrl = TX_SP_FLAG | TX_VAD_FLAG; move16 (); logic16 ();
262 }
263 else
264 {
265 test ();
266 if (txdtx_hangover == 0)
267 {
268 /* Hangover period is over, SID should be updated */
269
270 txdtx_N_elapsed = 0; move16 ();
271
272 /* Check if this is the first frame after hangover period */
273 test (); logic16 ();
274 if ((*txdtx_ctrl & TX_HANGOVER_ACTIVE) != 0)
275 {
276 *txdtx_ctrl = TX_PREV_HANGOVER_ACTIVE
277 | TX_SID_UPDATE; move16 (); logic16 ();
278 L_pn_seed_tx = PN_INITIAL_SEED; move32 ();
279 }
280 else
281 {
282 *txdtx_ctrl = TX_SID_UPDATE; move16 ();
283 }
284 }
285 else
286 {
287 /* Hangover period is not over, update hangover counter */
288 txdtx_hangover = sub (txdtx_hangover, 1);
289
290 /* Check if elapsed time from last SID update is greater than
291 threshold. If not, set SP=0 (although hangover period is not
292 over) and use old SID parameters for new SID frame.
293 N_elapsed counter must be summed with hangover counter in order
294 to avoid erroneus SP=1 decision in case when N_elapsed is grown
295 bigger than threshold and hangover period is still active */
296
297 test ();
298 if (sub (add (txdtx_N_elapsed, txdtx_hangover),
299 DTX_ELAPSED_THRESHOLD) < 0)
300 {
301 /* old SID frame should be used */
302 *txdtx_ctrl = TX_USE_OLD_SID; move16 ();
303 }
304 else
305 {
306 test (); logic16 ();
307 if ((*txdtx_ctrl & TX_HANGOVER_ACTIVE) != 0)
308 {
309 *txdtx_ctrl = TX_PREV_HANGOVER_ACTIVE
310 | TX_HANGOVER_ACTIVE
311 | TX_SP_FLAG; move16 (); logic16 (); logic16 ();
312 }
313 else
314 {
315 *txdtx_ctrl = TX_HANGOVER_ACTIVE
316 | TX_SP_FLAG; move16 (); logic16 ();
317 }
318 }
319 }
320 }
321
322 return;
323 }
324
325 /*************************************************************************
326 *
327 * FUNCTION NAME: rx_dtx
328 *
329 * PURPOSE: DTX handler of the speech decoder. Determines when to update
330 * the reference comfort noise parameters (LSF and gain) at the
331 * end of the speech burst. Also classifies the incoming frames
332 * according to SID flag and BFI flag
333 * and determines when the transmission is active during comfort
334 * noise insertion. This function also initializes the pseudo
335 * noise generator shift register.
336 *
337 * Operation of the RX DTX handler is based on measuring the
338 * lengths of speech bursts and the lengths of the pauses between
339 * speech bursts to determine when there exists a hangover period
340 * at the end of a speech burst. The idea is to keep in sync with
341 * the TX DTX handler to be able to update the reference comfort
342 * noise parameters at the same time instances.
343 *
344 * INPUTS: *rxdtx_ctrl Old decoder DTX control word
345 * TAF Time alignment flag
346 * bfi Bad frame indicator flag
347 * SID_flag Silence descriptor flag
348 *
349 * OUTPUTS: *rxdtx_ctrl Updated decoder DTX control word
350 * rx_dtx_state Updated state of comfort noise interpolation
351 * period (global variable)
352 * L_pn_seed_rx Initialized pseudo noise generator shift
353 * register (global variable)
354 *
355 * RETURN VALUE: none
356 *
357 *************************************************************************/
358
359 void rx_dtx (
360 Word16 *rxdtx_ctrl,
361 Word16 TAF,
362 Word16 bfi,
363 Word16 SID_flag
364 )
365 {
366 Word16 frame_type;
367
368 /* Frame classification according to bfi-flag and ternary-valued
369 SID flag. The frames between SID updates (not actually trans-
370 mitted) are also classified here; they will be discarded later
371 and provided with "NO TRANSMISSION"-flag */
372
373 test (); test ();
374 test (); test ();
375 test (); test ();
376 if ((sub (SID_flag, 2) == 0) && (bfi == 0))
377 {
378 frame_type = VALID_SID_FRAME; move16 ();
379 }
380 else if ((SID_flag == 0) && (bfi == 0))
381 {
382 frame_type = GOOD_SPEECH_FRAME; move16 ();
383 }
384 else if ((SID_flag == 0) && (bfi != 0))
385 {
386 frame_type = UNUSABLE_FRAME; move16 ();
387 }
388 else
389 {
390 frame_type = INVALID_SID_FRAME; move16 ();
391 }
392
393 /* Update of decoder state */
394 /* Previous frame was classified as a speech frame */
395 test (); logic16 ();
396 if ((*rxdtx_ctrl & RX_SP_FLAG) != 0)
397 {
398 test (); test (); test (); test ();
399 if (sub (frame_type, VALID_SID_FRAME) == 0)
400 {
401 *rxdtx_ctrl = RX_FIRST_SID_UPDATE; move16 ();
402 }
403 else if (sub (frame_type, INVALID_SID_FRAME) == 0)
404 {
405 *rxdtx_ctrl = RX_FIRST_SID_UPDATE
406 | RX_INVALID_SID_FRAME; move16 (); logic16();
407 }
408 else if (sub (frame_type, UNUSABLE_FRAME) == 0)
409 {
410 *rxdtx_ctrl = RX_SP_FLAG; move16 ();
411 }
412 else if (sub (frame_type, GOOD_SPEECH_FRAME) == 0)
413 {
414 *rxdtx_ctrl = RX_SP_FLAG; move16 ();
415 }
416 }
417 else
418 {
419 test (); test (); test (); test ();
420 if (sub (frame_type, VALID_SID_FRAME) == 0)
421 {
422 *rxdtx_ctrl = RX_CONT_SID_UPDATE; move16 ();
423 }
424 else if (sub (frame_type, INVALID_SID_FRAME) == 0)
425 {
426 *rxdtx_ctrl = RX_CONT_SID_UPDATE
427 | RX_INVALID_SID_FRAME; move16 (); logic16 ();
428 }
429 else if (sub (frame_type, UNUSABLE_FRAME) == 0)
430 {
431 *rxdtx_ctrl = RX_CNI_BFI; move16 ();
432 }
433 else if (sub (frame_type, GOOD_SPEECH_FRAME) == 0)
434 {
435 /* If the previous frame (during CNI period) was muted,
436 raise the RX_PREV_DTX_MUTING flag */
437 test (); logic16 ();
438 if ((*rxdtx_ctrl & RX_DTX_MUTING) != 0)
439 {
440 *rxdtx_ctrl = RX_SP_FLAG | RX_FIRST_SP_FLAG
441 | RX_PREV_DTX_MUTING; move16 (); logic16 ();
442 logic16 ();
443 }
444 else
445 {
446 *rxdtx_ctrl = RX_SP_FLAG | RX_FIRST_SP_FLAG; move16 ();
447 logic16 ();
448 }
449 }
450 }
451
452
453 test (); logic16 ();
454 if ((*rxdtx_ctrl & RX_SP_FLAG) != 0)
455 {
456 prev_SID_frames_lost = 0; move16 ();
457 rx_dtx_state = CN_INT_PERIOD - 1; move16 ();
458 }
459 else
460 {
461 /* First SID frame */
462 test (); logic16 ();
463 if ((*rxdtx_ctrl & RX_FIRST_SID_UPDATE) != 0)
464 {
465 prev_SID_frames_lost = 0; move16 ();
466 rx_dtx_state = CN_INT_PERIOD - 1; move16 ();
467 }
468
469 /* SID frame detected, but not the first SID */
470 test (); logic16 ();
471 if ((*rxdtx_ctrl & RX_CONT_SID_UPDATE) != 0)
472 {
473 prev_SID_frames_lost = 0; move16 ();
474
475 test (); test ();
476 if (sub (frame_type, VALID_SID_FRAME) == 0)
477 {
478 rx_dtx_state = 0; move16 ();
479 }
480 else if (sub (frame_type, INVALID_SID_FRAME) == 0)
481 {
482 test ();
483 if (sub(rx_dtx_state, (CN_INT_PERIOD - 1)) < 0)
484 {
485 rx_dtx_state = add(rx_dtx_state, 1); move16 ();
486 }
487 }
488 }
489
490 /* Bad frame received in CNI mode */
491 test (); logic16 ();
492 if ((*rxdtx_ctrl & RX_CNI_BFI) != 0)
493 {
494 test ();
495 if (sub (rx_dtx_state, (CN_INT_PERIOD - 1)) < 0)
496 {
497 rx_dtx_state = add (rx_dtx_state, 1); move16 ();
498 }
499
500 /* If an unusable frame is received during CNI period
501 when TAF == 1, the frame is classified as a lost
502 SID frame */
503 test ();
504 if (sub (TAF, 1) == 0)
505 {
506 *rxdtx_ctrl = *rxdtx_ctrl | RX_LOST_SID_FRAME;
507 move16 (); logic16 ();
508 prev_SID_frames_lost = add (prev_SID_frames_lost, 1);
509 }
510 else /* No transmission occurred */
511 {
512 *rxdtx_ctrl = *rxdtx_ctrl | RX_NO_TRANSMISSION;
513 move16 (); logic16 ();
514 }
515
516 test ();
517 if (sub (prev_SID_frames_lost, 1) > 0)
518 {
519 *rxdtx_ctrl = *rxdtx_ctrl | RX_DTX_MUTING;
520 move16 (); logic16 ();
521 }
522 }
523 }
524
525 /* N_elapsed (frames since last SID update) is incremented. If SID
526 is updated N_elapsed is cleared later in this function */
527
528 rxdtx_N_elapsed = add (rxdtx_N_elapsed, 1);
529
530 test (); logic16 ();
531 if ((*rxdtx_ctrl & RX_SP_FLAG) != 0)
532 {
533 rxdtx_aver_period = DTX_HANGOVER; move16 ();
534 }
535 else
536 {
537 test (); test ();
538 if (sub (rxdtx_N_elapsed, DTX_ELAPSED_THRESHOLD) > 0)
539 {
540 *rxdtx_ctrl |= RX_UPD_SID_QUANT_MEM; move16 (); logic16 ();
541 rxdtx_N_elapsed = 0; move16 ();
542 rxdtx_aver_period = 0; move16 ();
543 L_pn_seed_rx = PN_INITIAL_SEED; move32 ();
544 }
545 else if (rxdtx_aver_period == 0)
546 {
547 rxdtx_N_elapsed = 0; move16 ();
548 }
549 else
550 {
551 rxdtx_aver_period = sub (rxdtx_aver_period, 1);
552 }
553 }
554
555 return;
556 }
557
558 /*************************************************************************
559 *
560 * FUNCTION NAME: CN_encoding
561 *
562 * PURPOSE: Encoding of the comfort noise parameters into a SID frame.
563 * Use old SID parameters if necessary. Set the parameter
564 * indices not used by comfort noise parameters to zero.
565 *
566 * INPUTS: params[0..56] Comfort noise parameter frame from the
567 * speech encoder
568 * txdtx_ctrl TX DTX handler control word
569 *
570 * OUTPUTS: params[0..56] Comfort noise encoded parameter frame
571 *
572 * RETURN VALUE: none
573 *
574 *************************************************************************/
575
576 void CN_encoding (
577 Word16 params[],
578 Word16 txdtx_ctrl
579 )
580 {
581 Word16 i;
582
583 test (); logic16 ();
584 if ((txdtx_ctrl & TX_SID_UPDATE) != 0)
585 {
586 /* Store new CN parameters in memory to be used later as old
587 CN parameters */
588
589 /* LPC parameter indices */
590 for (i = 0; i < 5; i++)
591 {
592 old_CN_mem_tx[i] = params[i]; move16 ();
593 }
594 /* Codebook index computed in last subframe */
595 old_CN_mem_tx[5] = params[56]; move16 ();
596 }
597 test (); logic16 ();
598 if ((txdtx_ctrl & TX_USE_OLD_SID) != 0)
599 {
600 /* Use old CN parameters previously stored in memory */
601 for (i = 0; i < 5; i++)
602 {
603 params[i] = old_CN_mem_tx[i]; move16 ();
604 }
605 params[17] = old_CN_mem_tx[5]; move16 ();
606 params[30] = old_CN_mem_tx[5]; move16 ();
607 params[43] = old_CN_mem_tx[5]; move16 ();
608 params[56] = old_CN_mem_tx[5]; move16 ();
609 }
610 /* Set all the rest of the parameters to zero (SID codeword will
611 be written later) */
612 for (i = 0; i < 12; i++)
613 {
614 params[i + 5] = 0; move16 ();
615 params[i + 18] = 0; move16 ();
616 params[i + 31] = 0; move16 ();
617 params[i + 44] = 0; move16 ();
618 }
619
620 return;
621 }
622
623 /*************************************************************************
624 *
625 * FUNCTION NAME: sid_codeword_encoding
626 *
627 * PURPOSE: Encoding of the SID codeword into the SID frame. The SID
628 * codeword consists of 95 bits, all set to '1'.
629 *
630 * INPUTS: ser2[0..243] Serial-mode speech parameter frame before
631 * writing SID codeword into it
632 *
633 * OUTPUTS: ser2[0..243] Serial-mode speech parameter frame with
634 * SID codeword written into it
635 *
636 * RETURN VALUE: none
637 *
638 *************************************************************************/
639
640 void sid_codeword_encoding (
641 Word16 ser2[]
642 )
643 {
644 Word16 i;
645
646 for (i = 0; i < 95; i++)
647 {
648 ser2[SID_codeword_bit_idx[i]] = 1; move16 ();
649 }
650
651 return;
652 }
653
654 /*************************************************************************
655 *
656 * FUNCTION NAME: sid_frame_detection
657 *
658 * PURPOSE: Detecting of SID codeword from a received frame. The frames
659 * are classified into three categories based on how many bit
660 * errors occur in the SID codeword:
661 * - VALID SID FRAME
662 * - INVALID SID FRAME
663 * - SPEECH FRAME
664 *
665 * INPUTS: ser2[0..243] Received serial-mode speech parameter frame
666 *
667 * OUTPUTS: none
668 *
669 * RETURN VALUE: Ternary-valued SID classification flag
670 *
671 *************************************************************************/
672
673 Word16 sid_frame_detection (
674 Word16 ser2[]
675 )
676 {
677 Word16 i, nbr_errors, sid;
678
679 /* Search for bit errors in SID codeword */
680 nbr_errors = 0; move16 ();
681 for (i = 0; i < 95; i++)
682 {
683 test ();
684 if (ser2[SID_codeword_bit_idx[i]] == 0)
685 {
686 nbr_errors = add (nbr_errors, 1);
687 }
688 }
689
690 /* Frame classification */
691 test (); test ();
692 if (sub (nbr_errors, VALID_SID_THRESH) < 0)
693 { /* Valid SID frame */
694 sid = 2; move16 ();
695 }
696 else if (sub (nbr_errors, INVALID_SID_THRESH) < 0)
697 { /* Invalid SID frame */
698 sid = 1; move16 ();
699 }
700 else
701 { /* Speech frame */
702 sid = 0; move16 ();
703 }
704
705 return sid;
706 }
707
708 /*************************************************************************
709 *
710 * FUNCTION NAME: update_lsf_history
711 *
712 * PURPOSE: Update the LSF parameter history. The LSF parameters kept
713 * in the buffer are used later for computing the reference
714 * LSF parameter vector and the averaged LSF parameter vector.
715 *
716 * INPUTS: lsf1[0..9] LSF vector of the 1st half of the frame
717 * lsf2[0..9] LSF vector of the 2nd half of the frame
718 * lsf_old[0..DTX_HANGOVER-1][0..M-1]
719 * Old LSF history
720 *
721 * OUTPUTS: lsf_old[0..DTX_HANGOVER-1][0..M-1]
722 * Updated LSF history
723 *
724 * RETURN VALUE: none
725 *
726 *************************************************************************/
727
728 void update_lsf_history (
729 Word16 lsf1[M],
730 Word16 lsf2[M],
731 Word16 lsf_old[DTX_HANGOVER][M]
732 )
733 {
734 Word16 i, j, temp;
735
736 /* shift LSF data to make room for LSFs from current frame */
737 /* This can also be implemented by using circular buffering */
738
739 for (i = DTX_HANGOVER - 1; i > 0; i--)
740 {
741 for (j = 0; j < M; j++)
742 {
743 lsf_old[i][j] = lsf_old[i - 1][j]; move16 ();
744 }
745 }
746
747 /* Store new LSF data to lsf_old buffer */
748
749 for (i = 0; i < M; i++)
750 {
751 temp = add (shr (lsf1[i], 1), shr (lsf2[i], 1));
752 lsf_old[0][i] = temp; move16 ();
753 }
754
755 return;
756 }
757
758 /*************************************************************************
759 *
760 * FUNCTION NAME: update_lsf_p_CN
761 *
762 * PURPOSE: Update the reference LSF parameter vector. The reference
763 * vector is computed by averaging the quantized LSF parameter
764 * vectors which exist in the LSF parameter history.
765 *
766 * INPUTS: lsf_old[0..DTX_HANGOVER-1][0..M-1]
767 * LSF parameter history
768 *
769 * OUTPUTS: lsf_p_CN[0..9] Computed reference LSF parameter vector
770 *
771 * RETURN VALUE: none
772 *
773 *************************************************************************/
774
775 void update_lsf_p_CN (
776 Word16 lsf_old[DTX_HANGOVER][M],
777 Word16 lsf_p_CN[M]
778 )
779 {
780 Word16 i, j;
781 Word32 L_temp;
782
783 for (j = 0; j < M; j++)
784 {
785 L_temp = L_mult (INV_DTX_HANGOVER, lsf_old[0][j]);
786 for (i = 1; i < DTX_HANGOVER; i++)
787 {
788 L_temp = L_mac (L_temp, INV_DTX_HANGOVER, lsf_old[i][j]);
789 }
790 lsf_p_CN[j] = round (L_temp); move16 ();
791 }
792
793 return;
794 }
795
796 /*************************************************************************
797 *
798 * FUNCTION NAME: aver_lsf_history
799 *
800 * PURPOSE: Compute the averaged LSF parameter vector. Computation is
801 * performed by averaging the LSF parameter vectors which exist
802 * in the LSF parameter history, together with the LSF
803 * parameter vectors of the current frame.
804 *
805 * INPUTS: lsf_old[0..DTX_HANGOVER-1][0..M-1]
806 * LSF parameter history
807 * lsf1[0..M-1] LSF vector of the 1st half of the frame
808 * lsf2[0..M-1] LSF vector of the 2nd half of the frame
809 *
810 * OUTPUTS: lsf_aver[0..M-1] Averaged LSF parameter vector
811 *
812 * RETURN VALUE: none
813 *
814 *************************************************************************/
815
816 void aver_lsf_history (
817 Word16 lsf_old[DTX_HANGOVER][M],
818 Word16 lsf1[M],
819 Word16 lsf2[M],
820 Word16 lsf_aver[M]
821 )
822 {
823 Word16 i, j;
824 Word32 L_temp;
825
826 for (j = 0; j < M; j++)
827 {
828 L_temp = L_mult (0x3fff, lsf1[j]);
829 L_temp = L_mac (L_temp, 0x3fff, lsf2[j]);
830 L_temp = L_mult (INV_DTX_HANGOVER_P1, extract_h (L_temp));
831
832 for (i = 0; i < DTX_HANGOVER; i++)
833 {
834 L_temp = L_mac (L_temp, INV_DTX_HANGOVER_P1, lsf_old[i][j]);
835 }
836
837 lsf_aver[j] = extract_h (L_temp); move16 ();
838 }
839
840 return;
841 }
842
843 /*************************************************************************
844 *
845 * FUNCTION NAME: update_gain_code_history_tx
846 *
847 * PURPOSE: Update the fixed codebook gain parameter history of the
848 * encoder. The fixed codebook gain parameters kept in the buffer
849 * are used later for computing the reference fixed codebook
850 * gain parameter value and the averaged fixed codebook gain
851 * parameter value.
852 *
853 * INPUTS: new_gain_code New fixed codebook gain value
854 *
855 * gain_code_old_tx[0..4*DTX_HANGOVER-1]
856 * Old fixed codebook gain history of encoder
857 *
858 * OUTPUTS: gain_code_old_tx[0..4*DTX_HANGOVER-1]
859 * Updated fixed codebook gain history of encoder
860 *
861 * RETURN VALUE: none
862 *
863 *************************************************************************/
864
865 void update_gain_code_history_tx (
866 Word16 new_gain_code,
867 Word16 gain_code_old_tx[4 * DTX_HANGOVER]
868 )
869 {
870
871 /* Circular buffer */
872 gain_code_old_tx[buf_p_tx] = new_gain_code; move16 ();
873
874 test ();
875 if (sub (buf_p_tx, (4 * DTX_HANGOVER - 1)) == 0)
876 {
877 buf_p_tx = 0; move16 ();
878 }
879 else
880 {
881 buf_p_tx = add (buf_p_tx, 1);
882 }
883
884 return;
885 }
886
887 /*************************************************************************
888 *
889 * FUNCTION NAME: update_gain_code_history_rx
890 *
891 * PURPOSE: Update the fixed codebook gain parameter history of the
892 * decoder. The fixed codebook gain parameters kept in the buffer
893 * are used later for computing the reference fixed codebook
894 * gain parameter value.
895 *
896 * INPUTS: new_gain_code New fixed codebook gain value
897 *
898 * gain_code_old_tx[0..4*DTX_HANGOVER-1]
899 * Old fixed codebook gain history of decoder
900 *
901 * OUTPUTS: gain_code_old_tx[0..4*DTX_HANGOVER-1]
902 * Updated fixed codebk gain history of decoder
903 *
904 * RETURN VALUE: none
905 *
906 *************************************************************************/
907
908 void update_gain_code_history_rx (
909 Word16 new_gain_code,
910 Word16 gain_code_old_rx[4 * DTX_HANGOVER]
911 )
912 {
913
914 /* Circular buffer */
915 gain_code_old_rx[buf_p_rx] = new_gain_code; move16 ();
916
917 test ();
918 if (sub (buf_p_rx, (4 * DTX_HANGOVER - 1)) == 0)
919 {
920 buf_p_rx = 0; move16 ();
921 }
922 else
923 {
924 buf_p_rx = add (buf_p_rx, 1);
925 }
926
927 return;
928 }
929
930 /*************************************************************************
931 *
932 * FUNCTION NAME: compute_CN_excitation_gain
933 *
934 * PURPOSE: Compute the unquantized fixed codebook gain. Computation is
935 * based on the energy of the Linear Prediction residual signal.
936 *
937 * INPUTS: res2[0..39] Linear Prediction residual signal
938 *
939 * OUTPUTS: none
940 *
941 * RETURN VALUE: Unquantized fixed codebook gain
942 *
943 *************************************************************************/
944
945 Word16 compute_CN_excitation_gain (
946 Word16 res2[L_SUBFR]
947 )
948 {
949 Word16 i, norm, norm1, temp, overfl;
950 Word32 L_temp;
951
952 /* Compute the energy of the LP residual signal */
953
954 norm = 0; move16 ();
955 do
956 {
957 overfl = 0; move16 ();
958
959 L_temp = 0L; move32 ();
960 for (i = 0; i < L_SUBFR; i++)
961 {
962 temp = shr (res2[i], norm);
963 L_temp = L_mac (L_temp, temp, temp);
964 }
965
966 test ();
967 if (L_sub (L_temp, MAX_32) == 0)
968 {
969 norm = add (norm, 1);
970 overfl = 1; move16 (); /* Set the overflow flag */
971 }
972 test ();
973 }
974 while (overfl != 0);
975
976 L_temp = L_add (L_temp, 1L); /* Avoid the case of all zeros */
977
978 /* Take the square root of the obtained energy value (sqroot is a 2nd
979 order Taylor series approximation) */
980
981 norm1 = norm_l (L_temp);
982 temp = extract_h (L_shl (L_temp, norm1));
983 L_temp = L_mult (temp, temp);
984 L_temp = L_sub (805306368L, L_shr (L_temp, 3));
985 L_temp = L_add (L_temp, L_mult (24576, temp));
986
987 temp = extract_h (L_temp);
988 test (); logic16 ();
989 if ((norm1 & 0x0001) != 0)
990 {
991 temp = mult_r (temp, 23170);
992 norm1 = sub (norm1, 1);
993 }
994 /* Divide the result of sqroot operation by sqroot(10) */
995
996 temp = mult_r (temp, 10362);
997
998 /* Re-scale to get the final value */
999
1000 norm1 = shr (norm1, 1);
1001 norm1 = sub (norm1, norm);
1002
1003 test ();
1004 if (norm1 >= 0)
1005 {
1006 temp = shr (temp, norm1);
1007 }
1008 else
1009 {
1010 temp = shl (temp, abs_s (norm1));
1011 }
1012
1013 return temp;
1014 }
1015
1016 /*************************************************************************
1017 *
1018 * FUNCTION NAME: update_gcode0_CN
1019 *
1020 * PURPOSE: Update the reference fixed codebook gain parameter value.
1021 * The reference value is computed by averaging the quantized
1022 * fixed codebook gain parameter values which exist in the
1023 * fixed codebook gain parameter history.
1024 *
1025 * INPUTS: gain_code_old[0..4*DTX_HANGOVER-1]
1026 * fixed codebook gain parameter history
1027 *
1028 * OUTPUTS: none
1029 *
1030 * RETURN VALUE: Computed reference fixed codebook gain
1031 *
1032 *************************************************************************/
1033
1034 Word16 update_gcode0_CN (
1035 Word16 gain_code_old[4 * DTX_HANGOVER]
1036 )
1037 {
1038 Word16 i, j;
1039 Word32 L_temp, L_ret;
1040
1041 L_ret = 0L; move32 ();
1042 for (i = 0; i < DTX_HANGOVER; i++)
1043 {
1044 L_temp = L_mult (0x1fff, gain_code_old[4 * i]);
1045 for (j = 1; j < 4; j++)
1046 {
1047 L_temp = L_mac (L_temp, 0x1fff, gain_code_old[4 * i + j]);
1048 }
1049 L_ret = L_mac (L_ret, INV_DTX_HANGOVER, extract_h (L_temp));
1050 }
1051
1052 return extract_h (L_ret);
1053 }
1054
1055 /*************************************************************************
1056 *
1057 * FUNCTION NAME: aver_gain_code_history
1058 *
1059 * PURPOSE: Compute the averaged fixed codebook gain parameter value.
1060 * Computation is performed by averaging the fixed codebook
1061 * gain parameter values which exist in the fixed codebook
1062 * gain parameter history, together with the fixed codebook
1063 * gain parameter value of the current subframe.
1064 *
1065 * INPUTS: CN_excitation_gain
1066 * Unquantized fixed codebook gain value
1067 * of the current subframe
1068 * gain_code_old[0..4*DTX_HANGOVER-1]
1069 * fixed codebook gain parameter history
1070 *
1071 * OUTPUTS: none
1072 *
1073 * RETURN VALUE: Averaged fixed codebook gain value
1074 *
1075 *************************************************************************/
1076
1077 Word16 aver_gain_code_history (
1078 Word16 CN_excitation_gain,
1079 Word16 gain_code_old[4 * DTX_HANGOVER]
1080 )
1081 {
1082 Word16 i;
1083 Word32 L_ret;
1084
1085 L_ret = L_mult (0x470, CN_excitation_gain);
1086
1087 for (i = 0; i < (4 * DTX_HANGOVER); i++)
1088 {
1089 L_ret = L_mac (L_ret, 0x470, gain_code_old[i]);
1090 }
1091 return extract_h (L_ret);
1092 }
1093
1094 /*************************************************************************
1095 *
1096 * FUNCTION NAME: build_CN_code
1097 *
1098 * PURPOSE: Compute the comfort noise fixed codebook excitation. The
1099 * gains of the pulses are always +/-1.
1100 *
1101 * INPUTS: *seed Old CN generator shift register state
1102 *
1103 * OUTPUTS: cod[0..39] Generated comfort noise fixed codebook vector
1104 * *seed Updated CN generator shift register state
1105 *
1106 * RETURN VALUE: none
1107 *
1108 *************************************************************************/
1109
1110 void build_CN_code (
1111 Word16 cod[],
1112 Word32 *seed
1113 )
1114 {
1115 Word16 i, j, k;
1116
1117 for (i = 0; i < L_SUBFR; i++)
1118 {
1119 cod[i] = 0; move16 ();
1120 }
1121
1122 for (k = 0; k < NB_PULSE; k++)
1123 {
1124 i = pseudonoise (seed, 2); /* generate pulse position */
1125 i = shr (extract_l (L_mult (i, 10)), 1);
1126 i = add (i, k);
1127
1128 j = pseudonoise (seed, 1); /* generate sign */
1129
1130 test ();
1131 if (j > 0)
1132 {
1133 cod[i] = 4096; move16 ();
1134 }
1135 else
1136 {
1137 cod[i] = -4096; move16 ();
1138 }
1139 }
1140
1141 return;
1142 }
1143
1144 /*************************************************************************
1145 *
1146 * FUNCTION NAME: pseudonoise
1147 *
1148 * PURPOSE: Generate a random integer value to use in comfort noise
1149 * generation. The algorithm uses polynomial x^31 + x^3 + 1
1150 * (length of PN sequence is 2^31 - 1).
1151 *
1152 * INPUTS: *shift_reg Old CN generator shift register state
1153 *
1154 *
1155 * OUTPUTS: *shift_reg Updated CN generator shift register state
1156 *
1157 * RETURN VALUE: Generated random integer value
1158 *
1159 *************************************************************************/
1160
1161 Word16 pseudonoise (
1162 Word32 *shift_reg,
1163 Word16 no_bits
1164 )
1165 {
1166 Word16 noise_bits, Sn, i;
1167
1168 noise_bits = 0; move16 ();
1169 for (i = 0; i < no_bits; i++)
1170 {
1171 /* State n == 31 */
1172 test (); logic32 ();
1173 if ((*shift_reg & 0x00000001L) != 0)
1174 {
1175 Sn = 1; move16 ();
1176 }
1177 else
1178 {
1179 Sn = 0; move16 ();
1180 }
1181
1182 /* State n == 3 */
1183 test (); logic32 ();
1184 if ((*shift_reg & 0x10000000L) != 0)
1185 {
1186 Sn = Sn ^ 1; logic16 ();
1187 }
1188 else
1189 {
1190 Sn = Sn ^ 0; logic16 ();
1191 }
1192
1193 noise_bits = shl (noise_bits, 1);
1194 noise_bits = noise_bits | (extract_l (*shift_reg) & 1);
1195 logic16 (); logic16 ();
1196
1197 *shift_reg = L_shr (*shift_reg, 1); move32 ();
1198 test (); logic16 ();
1199 if (Sn & 1)
1200 {
1201 *shift_reg = *shift_reg | 0x40000000L; move32 (); logic32 ();
1202 }
1203 }
1204
1205 return noise_bits;
1206 }
1207
1208 /*************************************************************************
1209 *
1210 * FUNCTION NAME: interpolate_CN_param
1211 *
1212 * PURPOSE: Interpolate a comfort noise parameter value over the comfort
1213 * noise update period.
1214 *
1215 * INPUTS: old_param The older parameter of the interpolation
1216 * (the endpoint the interpolation is started
1217 * from)
1218 * new_param The newer parameter of the interpolation
1219 * (the endpoint the interpolation is ended to)
1220 * rx_dtx_state State of the comfort noise insertion period
1221 *
1222 * OUTPUTS: none
1223 *
1224 * RETURN VALUE: Interpolated CN parameter value
1225 *
1226 *************************************************************************/
1227
1228 Word16 interpolate_CN_param (
1229 Word16 old_param,
1230 Word16 new_param,
1231 Word16 rx_dtx_state
1232 )
1233 {
1234 static const Word16 interp_factor[CN_INT_PERIOD] =
1235 {
1236 0x0555, 0x0aaa, 0x1000, 0x1555, 0x1aaa, 0x2000,
1237 0x2555, 0x2aaa, 0x3000, 0x3555, 0x3aaa, 0x4000,
1238 0x4555, 0x4aaa, 0x5000, 0x5555, 0x5aaa, 0x6000,
1239 0x6555, 0x6aaa, 0x7000, 0x7555, 0x7aaa, 0x7fff};
1240 Word16 temp;
1241 Word32 L_temp;
1242
1243 L_temp = L_mult (interp_factor[rx_dtx_state], new_param);
1244 temp = sub (0x7fff, interp_factor[rx_dtx_state]);
1245 temp = add (temp, 1);
1246 L_temp = L_mac (L_temp, temp, old_param);
1247 temp = round (L_temp);
1248
1249 return temp;
1250 }
1251
1252 /*************************************************************************
1253 *
1254 * FUNCTION NAME: interpolate_CN_lsf
1255 *
1256 * PURPOSE: Interpolate comfort noise LSF parameter vector over the comfort
1257 * noise update period.
1258 *
1259 * INPUTS: lsf_old_CN[0..9]
1260 * The older LSF parameter vector of the
1261 * interpolation (the endpoint the interpolation
1262 * is started from)
1263 * lsf_new_CN[0..9]
1264 * The newer LSF parameter vector of the
1265 * interpolation (the endpoint the interpolation
1266 * is ended to)
1267 * rx_dtx_state State of the comfort noise insertion period
1268 *
1269 * OUTPUTS: lsf_interp_CN[0..9]
1270 * Interpolated LSF parameter vector
1271 *
1272 * RETURN VALUE: none
1273 *
1274 *************************************************************************/
1275
1276 void interpolate_CN_lsf (
1277 Word16 lsf_old_CN[M],
1278 Word16 lsf_new_CN[M],
1279 Word16 lsf_interp_CN[M],
1280 Word16 rx_dtx_state
1281 )
1282 {
1283 Word16 i;
1284
1285 for (i = 0; i < M; i++)
1286 {
1287 lsf_interp_CN[i] = interpolate_CN_param (lsf_old_CN[i],
1288 lsf_new_CN[i],
1289 rx_dtx_state); move16 ();
1290 }
1291
1292 return;
1293 }