summaryrefslogtreecommitdiffstats
path: root/media/libopus/celt/celt_decoder.c
blob: b978bb34d1b7015817637cd0172425aa8fabb60b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
/* Copyright (c) 2007-2008 CSIRO
   Copyright (c) 2007-2010 Xiph.Org Foundation
   Copyright (c) 2008 Gregory Maxwell
   Written by Jean-Marc Valin and Gregory Maxwell */
/*
   Redistribution and use in source and binary forms, with or without
   modification, are permitted provided that the following conditions
   are met:

   - Redistributions of source code must retain the above copyright
   notice, this list of conditions and the following disclaimer.

   - Redistributions in binary form must reproduce the above copyright
   notice, this list of conditions and the following disclaimer in the
   documentation and/or other materials provided with the distribution.

   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
   OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
   EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
   PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
   PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
   LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
   NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
   SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#define CELT_DECODER_C

#include "cpu_support.h"
#include "os_support.h"
#include "mdct.h"
#include <math.h>
#include "celt.h"
#include "pitch.h"
#include "bands.h"
#include "modes.h"
#include "entcode.h"
#include "quant_bands.h"
#include "rate.h"
#include "stack_alloc.h"
#include "mathops.h"
#include "float_cast.h"
#include <stdarg.h>
#include "celt_lpc.h"
#include "vq.h"

#if defined(SMALL_FOOTPRINT) && defined(FIXED_POINT)
#define NORM_ALIASING_HACK
#endif
/**********************************************************************/
/*                                                                    */
/*                             DECODER                                */
/*                                                                    */
/**********************************************************************/
#define DECODE_BUFFER_SIZE 2048

/** Decoder state
 @brief Decoder state
 */
struct OpusCustomDecoder {
   const OpusCustomMode *mode;
   int overlap;
   int channels;
   int stream_channels;

   int downsample;
   int start, end;
   int signalling;
   int arch;

   /* Everything beyond this point gets cleared on a reset */
#define DECODER_RESET_START rng

   opus_uint32 rng;
   int error;
   int last_pitch_index;
   int loss_count;
   int skip_plc;
   int postfilter_period;
   int postfilter_period_old;
   opus_val16 postfilter_gain;
   opus_val16 postfilter_gain_old;
   int postfilter_tapset;
   int postfilter_tapset_old;

   celt_sig preemph_memD[2];

   celt_sig _decode_mem[1]; /* Size = channels*(DECODE_BUFFER_SIZE+mode->overlap) */
   /* opus_val16 lpc[],  Size = channels*LPC_ORDER */
   /* opus_val16 oldEBands[], Size = 2*mode->nbEBands */
   /* opus_val16 oldLogE[], Size = 2*mode->nbEBands */
   /* opus_val16 oldLogE2[], Size = 2*mode->nbEBands */
   /* opus_val16 backgroundLogE[], Size = 2*mode->nbEBands */
};

int celt_decoder_get_size(int channels)
{
   const CELTMode *mode = opus_custom_mode_create(48000, 960, NULL);
   return opus_custom_decoder_get_size(mode, channels);
}

OPUS_CUSTOM_NOSTATIC int opus_custom_decoder_get_size(const CELTMode *mode, int channels)
{
   int size = sizeof(struct CELTDecoder)
            + (channels*(DECODE_BUFFER_SIZE+mode->overlap)-1)*sizeof(celt_sig)
            + channels*LPC_ORDER*sizeof(opus_val16)
            + 4*2*mode->nbEBands*sizeof(opus_val16);
   return size;
}

#ifdef CUSTOM_MODES
CELTDecoder *opus_custom_decoder_create(const CELTMode *mode, int channels, int *error)
{
   int ret;
   CELTDecoder *st = (CELTDecoder *)opus_alloc(opus_custom_decoder_get_size(mode, channels));
   ret = opus_custom_decoder_init(st, mode, channels);
   if (ret != OPUS_OK)
   {
      opus_custom_decoder_destroy(st);
      st = NULL;
   }
   if (error)
      *error = ret;
   return st;
}
#endif /* CUSTOM_MODES */

int celt_decoder_init(CELTDecoder *st, opus_int32 sampling_rate, int channels)
{
   int ret;
   ret = opus_custom_decoder_init(st, opus_custom_mode_create(48000, 960, NULL), channels);
   if (ret != OPUS_OK)
      return ret;
   st->downsample = resampling_factor(sampling_rate);
   if (st->downsample==0)
      return OPUS_BAD_ARG;
   else
      return OPUS_OK;
}

OPUS_CUSTOM_NOSTATIC int opus_custom_decoder_init(CELTDecoder *st, const CELTMode *mode, int channels)
{
   if (channels < 0 || channels > 2)
      return OPUS_BAD_ARG;

   if (st==NULL)
      return OPUS_ALLOC_FAIL;

   OPUS_CLEAR((char*)st, opus_custom_decoder_get_size(mode, channels));

   st->mode = mode;
   st->overlap = mode->overlap;
   st->stream_channels = st->channels = channels;

   st->downsample = 1;
   st->start = 0;
   st->end = st->mode->effEBands;
   st->signalling = 1;
   st->arch = opus_select_arch();

   opus_custom_decoder_ctl(st, OPUS_RESET_STATE);

   return OPUS_OK;
}

#ifdef CUSTOM_MODES
void opus_custom_decoder_destroy(CELTDecoder *st)
{
   opus_free(st);
}
#endif /* CUSTOM_MODES */


#ifndef RESYNTH
static
#endif
void deemphasis(celt_sig *in[], opus_val16 *pcm, int N, int C, int downsample, const opus_val16 *coef,
      celt_sig *mem, int accum)
{
   int c;
   int Nd;
   int apply_downsampling=0;
   opus_val16 coef0;
   VARDECL(celt_sig, scratch);
   SAVE_STACK;
#ifndef FIXED_POINT
   (void)accum;
   celt_assert(accum==0);
#endif
   ALLOC(scratch, N, celt_sig);
   coef0 = coef[0];
   Nd = N/downsample;
   c=0; do {
      int j;
      celt_sig * OPUS_RESTRICT x;
      opus_val16  * OPUS_RESTRICT y;
      celt_sig m = mem[c];
      x =in[c];
      y = pcm+c;
#ifdef CUSTOM_MODES
      if (coef[1] != 0)
      {
         opus_val16 coef1 = coef[1];
         opus_val16 coef3 = coef[3];
         for (j=0;j<N;j++)
         {
            celt_sig tmp = x[j] + m + VERY_SMALL;
            m = MULT16_32_Q15(coef0, tmp)
                          - MULT16_32_Q15(coef1, x[j]);
            tmp = SHL32(MULT16_32_Q15(coef3, tmp), 2);
            scratch[j] = tmp;
         }
         apply_downsampling=1;
      } else
#endif
      if (downsample>1)
      {
         /* Shortcut for the standard (non-custom modes) case */
         for (j=0;j<N;j++)
         {
            celt_sig tmp = x[j] + m + VERY_SMALL;
            m = MULT16_32_Q15(coef0, tmp);
            scratch[j] = tmp;
         }
         apply_downsampling=1;
      } else {
         /* Shortcut for the standard (non-custom modes) case */
#ifdef FIXED_POINT
         if (accum)
         {
            for (j=0;j<N;j++)
            {
               celt_sig tmp = x[j] + m + VERY_SMALL;
               m = MULT16_32_Q15(coef0, tmp);
               y[j*C] = SAT16(ADD32(y[j*C], SCALEOUT(SIG2WORD16(tmp))));
            }
         } else
#endif
         {
            for (j=0;j<N;j++)
            {
               celt_sig tmp = x[j] + m + VERY_SMALL;
               m = MULT16_32_Q15(coef0, tmp);
               y[j*C] = SCALEOUT(SIG2WORD16(tmp));
            }
         }
      }
      mem[c] = m;

      if (apply_downsampling)
      {
         /* Perform down-sampling */
#ifdef FIXED_POINT
         if (accum)
         {
            for (j=0;j<Nd;j++)
               y[j*C] = SAT16(ADD32(y[j*C], SCALEOUT(SIG2WORD16(scratch[j*downsample]))));
         } else
#endif
         {
            for (j=0;j<Nd;j++)
               y[j*C] = SCALEOUT(SIG2WORD16(scratch[j*downsample]));
         }
      }
   } while (++c<C);
   RESTORE_STACK;
}

#ifndef RESYNTH
static
#endif
void celt_synthesis(const CELTMode *mode, celt_norm *X, celt_sig * out_syn[],
                    opus_val16 *oldBandE, int start, int effEnd, int C, int CC,
                    int isTransient, int LM, int downsample,
                    int silence, int arch)
{
   int c, i;
   int M;
   int b;
   int B;
   int N, NB;
   int shift;
   int nbEBands;
   int overlap;
   VARDECL(celt_sig, freq);
   SAVE_STACK;

   overlap = mode->overlap;
   nbEBands = mode->nbEBands;
   N = mode->shortMdctSize<<LM;
   ALLOC(freq, N, celt_sig); /**< Interleaved signal MDCTs */
   M = 1<<LM;

   if (isTransient)
   {
      B = M;
      NB = mode->shortMdctSize;
      shift = mode->maxLM;
   } else {
      B = 1;
      NB = mode->shortMdctSize<<LM;
      shift = mode->maxLM-LM;
   }

   if (CC==2&&C==1)
   {
      /* Copying a mono streams to two channels */
      celt_sig *freq2;
      denormalise_bands(mode, X, freq, oldBandE, start, effEnd, M,
            downsample, silence);
      /* Store a temporary copy in the output buffer because the IMDCT destroys its input. */
      freq2 = out_syn[1]+overlap/2;
      OPUS_COPY(freq2, freq, N);
      for (b=0;b<B;b++)
         clt_mdct_backward(&mode->mdct, &freq2[b], out_syn[0]+NB*b, mode->window, overlap, shift, B, arch);
      for (b=0;b<B;b++)
         clt_mdct_backward(&mode->mdct, &freq[b], out_syn[1]+NB*b, mode->window, overlap, shift, B, arch);
   } else if (CC==1&&C==2)
   {
      /* Downmixing a stereo stream to mono */
      celt_sig *freq2;
      freq2 = out_syn[0]+overlap/2;
      denormalise_bands(mode, X, freq, oldBandE, start, effEnd, M,
            downsample, silence);
      /* Use the output buffer as temp array before downmixing. */
      denormalise_bands(mode, X+N, freq2, oldBandE+nbEBands, start, effEnd, M,
            downsample, silence);
      for (i=0;i<N;i++)
         freq[i] = HALF32(ADD32(freq[i],freq2[i]));
      for (b=0;b<B;b++)
         clt_mdct_backward(&mode->mdct, &freq[b], out_syn[0]+NB*b, mode->window, overlap, shift, B, arch);
   } else {
      /* Normal case (mono or stereo) */
      c=0; do {
         denormalise_bands(mode, X+c*N, freq, oldBandE+c*nbEBands, start, effEnd, M,
               downsample, silence);
         for (b=0;b<B;b++)
            clt_mdct_backward(&mode->mdct, &freq[b], out_syn[c]+NB*b, mode->window, overlap, shift, B, arch);
      } while (++c<CC);
   }
   RESTORE_STACK;
}

static void tf_decode(int start, int end, int isTransient, int *tf_res, int LM, ec_dec *dec)
{
   int i, curr, tf_select;
   int tf_select_rsv;
   int tf_changed;
   int logp;
   opus_uint32 budget;
   opus_uint32 tell;

   budget = dec->storage*8;
   tell = ec_tell(dec);
   logp = isTransient ? 2 : 4;
   tf_select_rsv = LM>0 && tell+logp+1<=budget;
   budget -= tf_select_rsv;
   tf_changed = curr = 0;
   for (i=start;i<end;i++)
   {
      if (tell+logp<=budget)
      {
         curr ^= ec_dec_bit_logp(dec, logp);
         tell = ec_tell(dec);
         tf_changed |= curr;
      }
      tf_res[i] = curr;
      logp = isTransient ? 4 : 5;
   }
   tf_select = 0;
   if (tf_select_rsv &&
     tf_select_table[LM][4*isTransient+0+tf_changed] !=
     tf_select_table[LM][4*isTransient+2+tf_changed])
   {
      tf_select = ec_dec_bit_logp(dec, 1);
   }
   for (i=start;i<end;i++)
   {
      tf_res[i] = tf_select_table[LM][4*isTransient+2*tf_select+tf_res[i]];
   }
}

/* The maximum pitch lag to allow in the pitch-based PLC. It's possible to save
   CPU time in the PLC pitch search by making this smaller than MAX_PERIOD. The
   current value corresponds to a pitch of 66.67 Hz. */
#define PLC_PITCH_LAG_MAX (720)
/* The minimum pitch lag to allow in the pitch-based PLC. This corresponds to a
   pitch of 480 Hz. */
#define PLC_PITCH_LAG_MIN (100)

static int celt_plc_pitch_search(celt_sig *decode_mem[2], int C, int arch)
{
   int pitch_index;
   VARDECL( opus_val16, lp_pitch_buf );
   SAVE_STACK;
   ALLOC( lp_pitch_buf, DECODE_BUFFER_SIZE>>1, opus_val16 );
   pitch_downsample(decode_mem, lp_pitch_buf,
         DECODE_BUFFER_SIZE, C, arch);
   pitch_search(lp_pitch_buf+(PLC_PITCH_LAG_MAX>>1), lp_pitch_buf,
         DECODE_BUFFER_SIZE-PLC_PITCH_LAG_MAX,
         PLC_PITCH_LAG_MAX-PLC_PITCH_LAG_MIN, &pitch_index, arch);
   pitch_index = PLC_PITCH_LAG_MAX-pitch_index;
   RESTORE_STACK;
   return pitch_index;
}

static void celt_decode_lost(CELTDecoder * OPUS_RESTRICT st, int N, int LM)
{
   int c;
   int i;
   const int C = st->channels;
   celt_sig *decode_mem[2];
   celt_sig *out_syn[2];
   opus_val16 *lpc;
   opus_val16 *oldBandE, *oldLogE, *oldLogE2, *backgroundLogE;
   const OpusCustomMode *mode;
   int nbEBands;
   int overlap;
   int start;
   int loss_count;
   int noise_based;
   const opus_int16 *eBands;
   SAVE_STACK;

   mode = st->mode;
   nbEBands = mode->nbEBands;
   overlap = mode->overlap;
   eBands = mode->eBands;

   c=0; do {
      decode_mem[c] = st->_decode_mem + c*(DECODE_BUFFER_SIZE+overlap);
      out_syn[c] = decode_mem[c]+DECODE_BUFFER_SIZE-N;
   } while (++c<C);
   lpc = (opus_val16*)(st->_decode_mem+(DECODE_BUFFER_SIZE+overlap)*C);
   oldBandE = lpc+C*LPC_ORDER;
   oldLogE = oldBandE + 2*nbEBands;
   oldLogE2 = oldLogE + 2*nbEBands;
   backgroundLogE = oldLogE2  + 2*nbEBands;

   loss_count = st->loss_count;
   start = st->start;
   noise_based = loss_count >= 5 || start != 0 || st->skip_plc;
   if (noise_based)
   {
      /* Noise-based PLC/CNG */
#ifdef NORM_ALIASING_HACK
      celt_norm *X;
#else
      VARDECL(celt_norm, X);
#endif
      opus_uint32 seed;
      int end;
      int effEnd;
      opus_val16 decay;
      end = st->end;
      effEnd = IMAX(start, IMIN(end, mode->effEBands));

#ifdef NORM_ALIASING_HACK
      /* This is an ugly hack that breaks aliasing rules and would be easily broken,
         but it saves almost 4kB of stack. */
      X = (celt_norm*)(out_syn[C-1]+overlap/2);
#else
      ALLOC(X, C*N, celt_norm);   /**< Interleaved normalised MDCTs */
#endif

      /* Energy decay */
      decay = loss_count==0 ? QCONST16(1.5f, DB_SHIFT) : QCONST16(.5f, DB_SHIFT);
      c=0; do
      {
         for (i=start;i<end;i++)
            oldBandE[c*nbEBands+i] = MAX16(backgroundLogE[c*nbEBands+i], oldBandE[c*nbEBands+i] - decay);
      } while (++c<C);
      seed = st->rng;
      for (c=0;c<C;c++)
      {
         for (i=start;i<effEnd;i++)
         {
            int j;
            int boffs;
            int blen;
            boffs = N*c+(eBands[i]<<LM);
            blen = (eBands[i+1]-eBands[i])<<LM;
            for (j=0;j<blen;j++)
            {
               seed = celt_lcg_rand(seed);
               X[boffs+j] = (celt_norm)((opus_int32)seed>>20);
            }
            renormalise_vector(X+boffs, blen, Q15ONE, st->arch);
         }
      }
      st->rng = seed;

      c=0; do {
         OPUS_MOVE(decode_mem[c], decode_mem[c]+N,
               DECODE_BUFFER_SIZE-N+(overlap>>1));
      } while (++c<C);

      celt_synthesis(mode, X, out_syn, oldBandE, start, effEnd, C, C, 0, LM, st->downsample, 0, st->arch);
   } else {
      /* Pitch-based PLC */
      const opus_val16 *window;
      opus_val16 fade = Q15ONE;
      int pitch_index;
      VARDECL(opus_val32, etmp);
      VARDECL(opus_val16, exc);

      if (loss_count == 0)
      {
         st->last_pitch_index = pitch_index = celt_plc_pitch_search(decode_mem, C, st->arch);
      } else {
         pitch_index = st->last_pitch_index;
         fade = QCONST16(.8f,15);
      }

      ALLOC(etmp, overlap, opus_val32);
      ALLOC(exc, MAX_PERIOD, opus_val16);
      window = mode->window;
      c=0; do {
         opus_val16 decay;
         opus_val16 attenuation;
         opus_val32 S1=0;
         celt_sig *buf;
         int extrapolation_offset;
         int extrapolation_len;
         int exc_length;
         int j;

         buf = decode_mem[c];
         for (i=0;i<MAX_PERIOD;i++) {
            exc[i] = ROUND16(buf[DECODE_BUFFER_SIZE-MAX_PERIOD+i], SIG_SHIFT);
         }

         if (loss_count == 0)
         {
            opus_val32 ac[LPC_ORDER+1];
            /* Compute LPC coefficients for the last MAX_PERIOD samples before
               the first loss so we can work in the excitation-filter domain. */
            _celt_autocorr(exc, ac, window, overlap,
                   LPC_ORDER, MAX_PERIOD, st->arch);
            /* Add a noise floor of -40 dB. */
#ifdef FIXED_POINT
            ac[0] += SHR32(ac[0],13);
#else
            ac[0] *= 1.0001f;
#endif
            /* Use lag windowing to stabilize the Levinson-Durbin recursion. */
            for (i=1;i<=LPC_ORDER;i++)
            {
               /*ac[i] *= exp(-.5*(2*M_PI*.002*i)*(2*M_PI*.002*i));*/
#ifdef FIXED_POINT
               ac[i] -= MULT16_32_Q15(2*i*i, ac[i]);
#else
               ac[i] -= ac[i]*(0.008f*0.008f)*i*i;
#endif
            }
            _celt_lpc(lpc+c*LPC_ORDER, ac, LPC_ORDER);
         }
         /* We want the excitation for 2 pitch periods in order to look for a
            decaying signal, but we can't get more than MAX_PERIOD. */
         exc_length = IMIN(2*pitch_index, MAX_PERIOD);
         /* Initialize the LPC history with the samples just before the start
            of the region for which we're computing the excitation. */
         {
            opus_val16 lpc_mem[LPC_ORDER];
            for (i=0;i<LPC_ORDER;i++)
            {
               lpc_mem[i] =
                     ROUND16(buf[DECODE_BUFFER_SIZE-exc_length-1-i], SIG_SHIFT);
            }
            /* Compute the excitation for exc_length samples before the loss. */
            celt_fir(exc+MAX_PERIOD-exc_length, lpc+c*LPC_ORDER,
                  exc+MAX_PERIOD-exc_length, exc_length, LPC_ORDER, lpc_mem, st->arch);
         }

         /* Check if the waveform is decaying, and if so how fast.
            We do this to avoid adding energy when concealing in a segment
            with decaying energy. */
         {
            opus_val32 E1=1, E2=1;
            int decay_length;
#ifdef FIXED_POINT
            int shift = IMAX(0,2*celt_zlog2(celt_maxabs16(&exc[MAX_PERIOD-exc_length], exc_length))-20);
#endif
            decay_length = exc_length>>1;
            for (i=0;i<decay_length;i++)
            {
               opus_val16 e;
               e = exc[MAX_PERIOD-decay_length+i];
               E1 += SHR32(MULT16_16(e, e), shift);
               e = exc[MAX_PERIOD-2*decay_length+i];
               E2 += SHR32(MULT16_16(e, e), shift);
            }
            E1 = MIN32(E1, E2);
            decay = celt_sqrt(frac_div32(SHR32(E1, 1), E2));
         }

         /* Move the decoder memory one frame to the left to give us room to
            add the data for the new frame. We ignore the overlap that extends
            past the end of the buffer, because we aren't going to use it. */
         OPUS_MOVE(buf, buf+N, DECODE_BUFFER_SIZE-N);

         /* Extrapolate from the end of the excitation with a period of
            "pitch_index", scaling down each period by an additional factor of
            "decay". */
         extrapolation_offset = MAX_PERIOD-pitch_index;
         /* We need to extrapolate enough samples to cover a complete MDCT
            window (including overlap/2 samples on both sides). */
         extrapolation_len = N+overlap;
         /* We also apply fading if this is not the first loss. */
         attenuation = MULT16_16_Q15(fade, decay);
         for (i=j=0;i<extrapolation_len;i++,j++)
         {
            opus_val16 tmp;
            if (j >= pitch_index) {
               j -= pitch_index;
               attenuation = MULT16_16_Q15(attenuation, decay);
            }
            buf[DECODE_BUFFER_SIZE-N+i] =
                  SHL32(EXTEND32(MULT16_16_Q15(attenuation,
                        exc[extrapolation_offset+j])), SIG_SHIFT);
            /* Compute the energy of the previously decoded signal whose
               excitation we're copying. */
            tmp = ROUND16(
                  buf[DECODE_BUFFER_SIZE-MAX_PERIOD-N+extrapolation_offset+j],
                  SIG_SHIFT);
            S1 += SHR32(MULT16_16(tmp, tmp), 8);
         }

         {
            opus_val16 lpc_mem[LPC_ORDER];
            /* Copy the last decoded samples (prior to the overlap region) to
               synthesis filter memory so we can have a continuous signal. */
            for (i=0;i<LPC_ORDER;i++)
               lpc_mem[i] = ROUND16(buf[DECODE_BUFFER_SIZE-N-1-i], SIG_SHIFT);
            /* Apply the synthesis filter to convert the excitation back into
               the signal domain. */
            celt_iir(buf+DECODE_BUFFER_SIZE-N, lpc+c*LPC_ORDER,
                  buf+DECODE_BUFFER_SIZE-N, extrapolation_len, LPC_ORDER,
                  lpc_mem, st->arch);
         }

         /* Check if the synthesis energy is higher than expected, which can
            happen with the signal changes during our window. If so,
            attenuate. */
         {
            opus_val32 S2=0;
            for (i=0;i<extrapolation_len;i++)
            {
               opus_val16 tmp = ROUND16(buf[DECODE_BUFFER_SIZE-N+i], SIG_SHIFT);
               S2 += SHR32(MULT16_16(tmp, tmp), 8);
            }
            /* This checks for an "explosion" in the synthesis. */
#ifdef FIXED_POINT
            if (!(S1 > SHR32(S2,2)))
#else
            /* The float test is written this way to catch NaNs in the output
               of the IIR filter at the same time. */
            if (!(S1 > 0.2f*S2))
#endif
            {
               for (i=0;i<extrapolation_len;i++)
                  buf[DECODE_BUFFER_SIZE-N+i] = 0;
            } else if (S1 < S2)
            {
               opus_val16 ratio = celt_sqrt(frac_div32(SHR32(S1,1)+1,S2+1));
               for (i=0;i<overlap;i++)
               {
                  opus_val16 tmp_g = Q15ONE
                        - MULT16_16_Q15(window[i], Q15ONE-ratio);
                  buf[DECODE_BUFFER_SIZE-N+i] =
                        MULT16_32_Q15(tmp_g, buf[DECODE_BUFFER_SIZE-N+i]);
               }
               for (i=overlap;i<extrapolation_len;i++)
               {
                  buf[DECODE_BUFFER_SIZE-N+i] =
                        MULT16_32_Q15(ratio, buf[DECODE_BUFFER_SIZE-N+i]);
               }
            }
         }

         /* Apply the pre-filter to the MDCT overlap for the next frame because
            the post-filter will be re-applied in the decoder after the MDCT
            overlap. */
         comb_filter(etmp, buf+DECODE_BUFFER_SIZE,
              st->postfilter_period, st->postfilter_period, overlap,
              -st->postfilter_gain, -st->postfilter_gain,
              st->postfilter_tapset, st->postfilter_tapset, NULL, 0, st->arch);

         /* Simulate TDAC on the concealed audio so that it blends with the
            MDCT of the next frame. */
         for (i=0;i<overlap/2;i++)
         {
            buf[DECODE_BUFFER_SIZE+i] =
               MULT16_32_Q15(window[i], etmp[overlap-1-i])
               + MULT16_32_Q15(window[overlap-i-1], etmp[i]);
         }
      } while (++c<C);
   }

   st->loss_count = loss_count+1;

   RESTORE_STACK;
}

int celt_decode_with_ec(CELTDecoder * OPUS_RESTRICT st, const unsigned char *data,
      int len, opus_val16 * OPUS_RESTRICT pcm, int frame_size, ec_dec *dec, int accum)
{
   int c, i, N;
   int spread_decision;
   opus_int32 bits;
   ec_dec _dec;
#ifdef NORM_ALIASING_HACK
   celt_norm *X;
#else
   VARDECL(celt_norm, X);
#endif
   VARDECL(int, fine_quant);
   VARDECL(int, pulses);
   VARDECL(int, cap);
   VARDECL(int, offsets);
   VARDECL(int, fine_priority);
   VARDECL(int, tf_res);
   VARDECL(unsigned char, collapse_masks);
   celt_sig *decode_mem[2];
   celt_sig *out_syn[2];
   opus_val16 *lpc;
   opus_val16 *oldBandE, *oldLogE, *oldLogE2, *backgroundLogE;

   int shortBlocks;
   int isTransient;
   int intra_ener;
   const int CC = st->channels;
   int LM, M;
   int start;
   int end;
   int effEnd;
   int codedBands;
   int alloc_trim;
   int postfilter_pitch;
   opus_val16 postfilter_gain;
   int intensity=0;
   int dual_stereo=0;
   opus_int32 total_bits;
   opus_int32 balance;
   opus_int32 tell;
   int dynalloc_logp;
   int postfilter_tapset;
   int anti_collapse_rsv;
   int anti_collapse_on=0;
   int silence;
   int C = st->stream_channels;
   const OpusCustomMode *mode;
   int nbEBands;
   int overlap;
   const opus_int16 *eBands;
   ALLOC_STACK;

   mode = st->mode;
   nbEBands = mode->nbEBands;
   overlap = mode->overlap;
   eBands = mode->eBands;
   start = st->start;
   end = st->end;
   frame_size *= st->downsample;

   lpc = (opus_val16*)(st->_decode_mem+(DECODE_BUFFER_SIZE+overlap)*CC);
   oldBandE = lpc+CC*LPC_ORDER;
   oldLogE = oldBandE + 2*nbEBands;
   oldLogE2 = oldLogE + 2*nbEBands;
   backgroundLogE = oldLogE2  + 2*nbEBands;

#ifdef CUSTOM_MODES
   if (st->signalling && data!=NULL)
   {
      int data0=data[0];
      /* Convert "standard mode" to Opus header */
      if (mode->Fs==48000 && mode->shortMdctSize==120)
      {
         data0 = fromOpus(data0);
         if (data0<0)
            return OPUS_INVALID_PACKET;
      }
      st->end = end = IMAX(1, mode->effEBands-2*(data0>>5));
      LM = (data0>>3)&0x3;
      C = 1 + ((data0>>2)&0x1);
      data++;
      len--;
      if (LM>mode->maxLM)
         return OPUS_INVALID_PACKET;
      if (frame_size < mode->shortMdctSize<<LM)
         return OPUS_BUFFER_TOO_SMALL;
      else
         frame_size = mode->shortMdctSize<<LM;
   } else {
#else
   {
#endif
      for (LM=0;LM<=mode->maxLM;LM++)
         if (mode->shortMdctSize<<LM==frame_size)
            break;
      if (LM>mode->maxLM)
         return OPUS_BAD_ARG;
   }
   M=1<<LM;

   if (len<0 || len>1275 || pcm==NULL)
      return OPUS_BAD_ARG;

   N = M*mode->shortMdctSize;
   c=0; do {
      decode_mem[c] = st->_decode_mem + c*(DECODE_BUFFER_SIZE+overlap);
      out_syn[c] = decode_mem[c]+DECODE_BUFFER_SIZE-N;
   } while (++c<CC);

   effEnd = end;
   if (effEnd > mode->effEBands)
      effEnd = mode->effEBands;

   if (data == NULL || len<=1)
   {
      celt_decode_lost(st, N, LM);
      deemphasis(out_syn, pcm, N, CC, st->downsample, mode->preemph, st->preemph_memD, accum);
      RESTORE_STACK;
      return frame_size/st->downsample;
   }

   /* Check if there are at least two packets received consecutively before
    * turning on the pitch-based PLC */
   st->skip_plc = st->loss_count != 0;

   if (dec == NULL)
   {
      ec_dec_init(&_dec,(unsigned char*)data,len);
      dec = &_dec;
   }

   if (C==1)
   {
      for (i=0;i<nbEBands;i++)
         oldBandE[i]=MAX16(oldBandE[i],oldBandE[nbEBands+i]);
   }

   total_bits = len*8;
   tell = ec_tell(dec);

   if (tell >= total_bits)
      silence = 1;
   else if (tell==1)
      silence = ec_dec_bit_logp(dec, 15);
   else
      silence = 0;
   if (silence)
   {
      /* Pretend we've read all the remaining bits */
      tell = len*8;
      dec->nbits_total+=tell-ec_tell(dec);
   }

   postfilter_gain = 0;
   postfilter_pitch = 0;
   postfilter_tapset = 0;
   if (start==0 && tell+16 <= total_bits)
   {
      if(ec_dec_bit_logp(dec, 1))
      {
         int qg, octave;
         octave = ec_dec_uint(dec, 6);
         postfilter_pitch = (16<<octave)+ec_dec_bits(dec, 4+octave)-1;
         qg = ec_dec_bits(dec, 3);
         if (ec_tell(dec)+2<=total_bits)
            postfilter_tapset = ec_dec_icdf(dec, tapset_icdf, 2);
         postfilter_gain = QCONST16(.09375f,15)*(qg+1);
      }
      tell = ec_tell(dec);
   }

   if (LM > 0 && tell+3 <= total_bits)
   {
      isTransient = ec_dec_bit_logp(dec, 3);
      tell = ec_tell(dec);
   }
   else
      isTransient = 0;

   if (isTransient)
      shortBlocks = M;
   else
      shortBlocks = 0;

   /* Decode the global flags (first symbols in the stream) */
   intra_ener = tell+3<=total_bits ? ec_dec_bit_logp(dec, 3) : 0;
   /* Get band energies */
   unquant_coarse_energy(mode, start, end, oldBandE,
         intra_ener, dec, C, LM);

   ALLOC(tf_res, nbEBands, int);
   tf_decode(start, end, isTransient, tf_res, LM, dec);

   tell = ec_tell(dec);
   spread_decision = SPREAD_NORMAL;
   if (tell+4 <= total_bits)
      spread_decision = ec_dec_icdf(dec, spread_icdf, 5);

   ALLOC(cap, nbEBands, int);

   init_caps(mode,cap,LM,C);

   ALLOC(offsets, nbEBands, int);

   dynalloc_logp = 6;
   total_bits<<=BITRES;
   tell = ec_tell_frac(dec);
   for (i=start;i<end;i++)
   {
      int width, quanta;
      int dynalloc_loop_logp;
      int boost;
      width = C*(eBands[i+1]-eBands[i])<<LM;
      /* quanta is 6 bits, but no more than 1 bit/sample
         and no less than 1/8 bit/sample */
      quanta = IMIN(width<<BITRES, IMAX(6<<BITRES, width));
      dynalloc_loop_logp = dynalloc_logp;
      boost = 0;
      while (tell+(dynalloc_loop_logp<<BITRES) < total_bits && boost < cap[i])
      {
         int flag;
         flag = ec_dec_bit_logp(dec, dynalloc_loop_logp);
         tell = ec_tell_frac(dec);
         if (!flag)
            break;
         boost += quanta;
         total_bits -= quanta;
         dynalloc_loop_logp = 1;
      }
      offsets[i] = boost;
      /* Making dynalloc more likely */
      if (boost>0)
         dynalloc_logp = IMAX(2, dynalloc_logp-1);
   }

   ALLOC(fine_quant, nbEBands, int);
   alloc_trim = tell+(6<<BITRES) <= total_bits ?
         ec_dec_icdf(dec, trim_icdf, 7) : 5;

   bits = (((opus_int32)len*8)<<BITRES) - ec_tell_frac(dec) - 1;
   anti_collapse_rsv = isTransient&&LM>=2&&bits>=((LM+2)<<BITRES) ? (1<<BITRES) : 0;
   bits -= anti_collapse_rsv;

   ALLOC(pulses, nbEBands, int);
   ALLOC(fine_priority, nbEBands, int);

   codedBands = compute_allocation(mode, start, end, offsets, cap,
         alloc_trim, &intensity, &dual_stereo, bits, &balance, pulses,
         fine_quant, fine_priority, C, LM, dec, 0, 0, 0);

   unquant_fine_energy(mode, start, end, oldBandE, fine_quant, dec, C);

   c=0; do {
      OPUS_MOVE(decode_mem[c], decode_mem[c]+N, DECODE_BUFFER_SIZE-N+overlap/2);
   } while (++c<CC);

   /* Decode fixed codebook */
   ALLOC(collapse_masks, C*nbEBands, unsigned char);

#ifdef NORM_ALIASING_HACK
   /* This is an ugly hack that breaks aliasing rules and would be easily broken,
      but it saves almost 4kB of stack. */
   X = (celt_norm*)(out_syn[CC-1]+overlap/2);
#else
   ALLOC(X, C*N, celt_norm);   /**< Interleaved normalised MDCTs */
#endif

   quant_all_bands(0, mode, start, end, X, C==2 ? X+N : NULL, collapse_masks,
         NULL, pulses, shortBlocks, spread_decision, dual_stereo, intensity, tf_res,
         len*(8<<BITRES)-anti_collapse_rsv, balance, dec, LM, codedBands, &st->rng, st->arch);

   if (anti_collapse_rsv > 0)
   {
      anti_collapse_on = ec_dec_bits(dec, 1);
   }

   unquant_energy_finalise(mode, start, end, oldBandE,
         fine_quant, fine_priority, len*8-ec_tell(dec), dec, C);

   if (anti_collapse_on)
      anti_collapse(mode, X, collapse_masks, LM, C, N,
            start, end, oldBandE, oldLogE, oldLogE2, pulses, st->rng, st->arch);

   if (silence)
   {
      for (i=0;i<C*nbEBands;i++)
         oldBandE[i] = -QCONST16(28.f,DB_SHIFT);
   }

   celt_synthesis(mode, X, out_syn, oldBandE, start, effEnd,
                  C, CC, isTransient, LM, st->downsample, silence, st->arch);

   c=0; do {
      st->postfilter_period=IMAX(st->postfilter_period, COMBFILTER_MINPERIOD);
      st->postfilter_period_old=IMAX(st->postfilter_period_old, COMBFILTER_MINPERIOD);
      comb_filter(out_syn[c], out_syn[c], st->postfilter_period_old, st->postfilter_period, mode->shortMdctSize,
            st->postfilter_gain_old, st->postfilter_gain, st->postfilter_tapset_old, st->postfilter_tapset,
            mode->window, overlap, st->arch);
      if (LM!=0)
         comb_filter(out_syn[c]+mode->shortMdctSize, out_syn[c]+mode->shortMdctSize, st->postfilter_period, postfilter_pitch, N-mode->shortMdctSize,
               st->postfilter_gain, postfilter_gain, st->postfilter_tapset, postfilter_tapset,
               mode->window, overlap, st->arch);

   } while (++c<CC);
   st->postfilter_period_old = st->postfilter_period;
   st->postfilter_gain_old = st->postfilter_gain;
   st->postfilter_tapset_old = st->postfilter_tapset;
   st->postfilter_period = postfilter_pitch;
   st->postfilter_gain = postfilter_gain;
   st->postfilter_tapset = postfilter_tapset;
   if (LM!=0)
   {
      st->postfilter_period_old = st->postfilter_period;
      st->postfilter_gain_old = st->postfilter_gain;
      st->postfilter_tapset_old = st->postfilter_tapset;
   }

   if (C==1)
      OPUS_COPY(&oldBandE[nbEBands], oldBandE, nbEBands);

   /* In case start or end were to change */
   if (!isTransient)
   {
      opus_val16 max_background_increase;
      OPUS_COPY(oldLogE2, oldLogE, 2*nbEBands);
      OPUS_COPY(oldLogE, oldBandE, 2*nbEBands);
      /* In normal circumstances, we only allow the noise floor to increase by
         up to 2.4 dB/second, but when we're in DTX, we allow up to 6 dB
         increase for each update.*/
      if (st->loss_count < 10)
         max_background_increase = M*QCONST16(0.001f,DB_SHIFT);
      else
         max_background_increase = QCONST16(1.f,DB_SHIFT);
      for (i=0;i<2*nbEBands;i++)
         backgroundLogE[i] = MIN16(backgroundLogE[i] + max_background_increase, oldBandE[i]);
   } else {
      for (i=0;i<2*nbEBands;i++)
         oldLogE[i] = MIN16(oldLogE[i], oldBandE[i]);
   }
   c=0; do
   {
      for (i=0;i<start;i++)
      {
         oldBandE[c*nbEBands+i]=0;
         oldLogE[c*nbEBands+i]=oldLogE2[c*nbEBands+i]=-QCONST16(28.f,DB_SHIFT);
      }
      for (i=end;i<nbEBands;i++)
      {
         oldBandE[c*nbEBands+i]=0;
         oldLogE[c*nbEBands+i]=oldLogE2[c*nbEBands+i]=-QCONST16(28.f,DB_SHIFT);
      }
   } while (++c<2);
   st->rng = dec->rng;

   deemphasis(out_syn, pcm, N, CC, st->downsample, mode->preemph, st->preemph_memD, accum);
   st->loss_count = 0;
   RESTORE_STACK;
   if (ec_tell(dec) > 8*len)
      return OPUS_INTERNAL_ERROR;
   if(ec_get_error(dec))
      st->error = 1;
   return frame_size/st->downsample;
}


#ifdef CUSTOM_MODES

#ifdef FIXED_POINT
int opus_custom_decode(CELTDecoder * OPUS_RESTRICT st, const unsigned char *data, int len, opus_int16 * OPUS_RESTRICT pcm, int frame_size)
{
   return celt_decode_with_ec(st, data, len, pcm, frame_size, NULL, 0);
}

#ifndef DISABLE_FLOAT_API
int opus_custom_decode_float(CELTDecoder * OPUS_RESTRICT st, const unsigned char *data, int len, float * OPUS_RESTRICT pcm, int frame_size)
{
   int j, ret, C, N;
   VARDECL(opus_int16, out);
   ALLOC_STACK;

   if (pcm==NULL)
      return OPUS_BAD_ARG;

   C = st->channels;
   N = frame_size;

   ALLOC(out, C*N, opus_int16);
   ret=celt_decode_with_ec(st, data, len, out, frame_size, NULL, 0);
   if (ret>0)
      for (j=0;j<C*ret;j++)
         pcm[j]=out[j]*(1.f/32768.f);

   RESTORE_STACK;
   return ret;
}
#endif /* DISABLE_FLOAT_API */

#else

int opus_custom_decode_float(CELTDecoder * OPUS_RESTRICT st, const unsigned char *data, int len, float * OPUS_RESTRICT pcm, int frame_size)
{
   return celt_decode_with_ec(st, data, len, pcm, frame_size, NULL, 0);
}

int opus_custom_decode(CELTDecoder * OPUS_RESTRICT st, const unsigned char *data, int len, opus_int16 * OPUS_RESTRICT pcm, int frame_size)
{
   int j, ret, C, N;
   VARDECL(celt_sig, out);
   ALLOC_STACK;

   if (pcm==NULL)
      return OPUS_BAD_ARG;

   C = st->channels;
   N = frame_size;
   ALLOC(out, C*N, celt_sig);

   ret=celt_decode_with_ec(st, data, len, out, frame_size, NULL, 0);

   if (ret>0)
      for (j=0;j<C*ret;j++)
         pcm[j] = FLOAT2INT16 (out[j]);

   RESTORE_STACK;
   return ret;
}

#endif
#endif /* CUSTOM_MODES */

int opus_custom_decoder_ctl(CELTDecoder * OPUS_RESTRICT st, int request, ...)
{
   va_list ap;

   va_start(ap, request);
   switch (request)
   {
      case CELT_SET_START_BAND_REQUEST:
      {
         opus_int32 value = va_arg(ap, opus_int32);
         if (value<0 || value>=st->mode->nbEBands)
            goto bad_arg;
         st->start = value;
      }
      break;
      case CELT_SET_END_BAND_REQUEST:
      {
         opus_int32 value = va_arg(ap, opus_int32);
         if (value<1 || value>st->mode->nbEBands)
            goto bad_arg;
         st->end = value;
      }
      break;
      case CELT_SET_CHANNELS_REQUEST:
      {
         opus_int32 value = va_arg(ap, opus_int32);
         if (value<1 || value>2)
            goto bad_arg;
         st->stream_channels = value;
      }
      break;
      case CELT_GET_AND_CLEAR_ERROR_REQUEST:
      {
         opus_int32 *value = va_arg(ap, opus_int32*);
         if (value==NULL)
            goto bad_arg;
         *value=st->error;
         st->error = 0;
      }
      break;
      case OPUS_GET_LOOKAHEAD_REQUEST:
      {
         opus_int32 *value = va_arg(ap, opus_int32*);
         if (value==NULL)
            goto bad_arg;
         *value = st->overlap/st->downsample;
      }
      break;
      case OPUS_RESET_STATE:
      {
         int i;
         opus_val16 *lpc, *oldBandE, *oldLogE, *oldLogE2;
         lpc = (opus_val16*)(st->_decode_mem+(DECODE_BUFFER_SIZE+st->overlap)*st->channels);
         oldBandE = lpc+st->channels*LPC_ORDER;
         oldLogE = oldBandE + 2*st->mode->nbEBands;
         oldLogE2 = oldLogE + 2*st->mode->nbEBands;
         OPUS_CLEAR((char*)&st->DECODER_RESET_START,
               opus_custom_decoder_get_size(st->mode, st->channels)-
               ((char*)&st->DECODER_RESET_START - (char*)st));
         for (i=0;i<2*st->mode->nbEBands;i++)
            oldLogE[i]=oldLogE2[i]=-QCONST16(28.f,DB_SHIFT);
         st->skip_plc = 1;
      }
      break;
      case OPUS_GET_PITCH_REQUEST:
      {
         opus_int32 *value = va_arg(ap, opus_int32*);
         if (value==NULL)
            goto bad_arg;
         *value = st->postfilter_period;
      }
      break;
      case CELT_GET_MODE_REQUEST:
      {
         const CELTMode ** value = va_arg(ap, const CELTMode**);
         if (value==0)
            goto bad_arg;
         *value=st->mode;
      }
      break;
      case CELT_SET_SIGNALLING_REQUEST:
      {
         opus_int32 value = va_arg(ap, opus_int32);
         st->signalling = value;
      }
      break;
      case OPUS_GET_FINAL_RANGE_REQUEST:
      {
         opus_uint32 * value = va_arg(ap, opus_uint32 *);
         if (value==0)
            goto bad_arg;
         *value=st->rng;
      }
      break;
      default:
         goto bad_request;
   }
   va_end(ap);
   return OPUS_OK;
bad_arg:
   va_end(ap);
   return OPUS_BAD_ARG;
bad_request:
      va_end(ap);
  return OPUS_UNIMPLEMENTED;
}