aboutsummaryrefslogtreecommitdiff
path: root/webrtc/modules/video_coding/main/source/media_opt_util.cc
blob: 51decbed97d2b5a59608337e47c93ccb8762020e (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
/*
 *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */

#include "webrtc/modules/video_coding/main/source/media_opt_util.h"

#include <algorithm>
#include <float.h>
#include <limits.h>
#include <math.h>

#include "webrtc/modules/interface/module_common_types.h"
#include "webrtc/modules/video_coding/codecs/vp8/include/vp8_common_types.h"
#include "webrtc/modules/video_coding/main/interface/video_coding_defines.h"
#include "webrtc/modules/video_coding/main/source/fec_tables_xor.h"
#include "webrtc/modules/video_coding/main/source/nack_fec_tables.h"

namespace webrtc {
// Max value of loss rates in off-line model
static const int kPacketLossMax = 129;

namespace media_optimization {

VCMProtectionMethod::VCMProtectionMethod()
    : _effectivePacketLoss(0),
      _protectionFactorK(0),
      _protectionFactorD(0),
      _scaleProtKey(2.0f),
      _maxPayloadSize(1460),
      _qmRobustness(new VCMQmRobustness()),
      _useUepProtectionK(false),
      _useUepProtectionD(true),
      _corrFecCost(1.0),
      _type(kNone) {
}

VCMProtectionMethod::~VCMProtectionMethod()
{
    delete _qmRobustness;
}
void
VCMProtectionMethod::UpdateContentMetrics(const
                                          VideoContentMetrics* contentMetrics)
{
    _qmRobustness->UpdateContent(contentMetrics);
}

VCMNackFecMethod::VCMNackFecMethod(int64_t lowRttNackThresholdMs,
                                   int64_t highRttNackThresholdMs)
    : VCMFecMethod(),
      _lowRttNackMs(lowRttNackThresholdMs),
      _highRttNackMs(highRttNackThresholdMs),
      _maxFramesFec(1) {
  assert(lowRttNackThresholdMs >= -1 && highRttNackThresholdMs >= -1);
  assert(highRttNackThresholdMs == -1 ||
         lowRttNackThresholdMs <= highRttNackThresholdMs);
  assert(lowRttNackThresholdMs > -1 || highRttNackThresholdMs == -1);
  _type = kNackFec;
}

VCMNackFecMethod::~VCMNackFecMethod()
{
    //
}
bool
VCMNackFecMethod::ProtectionFactor(const VCMProtectionParameters* parameters)
{
    // Hybrid Nack FEC has three operational modes:
    // 1. Low RTT (below kLowRttNackMs) - Nack only: Set FEC rate
    //    (_protectionFactorD) to zero. -1 means no FEC.
    // 2. High RTT (above _highRttNackMs) - FEC Only: Keep FEC factors.
    //    -1 means always allow NACK.
    // 3. Medium RTT values - Hybrid mode: We will only nack the
    //    residual following the decoding of the FEC (refer to JB logic). FEC
    //    delta protection factor will be adjusted based on the RTT.

    // Otherwise: we count on FEC; if the RTT is below a threshold, then we
    // nack the residual, based on a decision made in the JB.

    // Compute the protection factors
    VCMFecMethod::ProtectionFactor(parameters);
    if (_lowRttNackMs == -1 || parameters->rtt < _lowRttNackMs)
    {
        _protectionFactorD = 0;
        VCMFecMethod::UpdateProtectionFactorD(_protectionFactorD);
    }

    // When in Hybrid mode (RTT range), adjust FEC rates based on the
    // RTT (NACK effectiveness) - adjustment factor is in the range [0,1].
    else if (_highRttNackMs == -1 || parameters->rtt < _highRttNackMs)
    {
        // TODO(mikhal): Disabling adjustment temporarily.
        // uint16_t rttIndex = (uint16_t) parameters->rtt;
        float adjustRtt = 1.0f;// (float)VCMNackFecTable[rttIndex] / 100.0f;

        // Adjust FEC with NACK on (for delta frame only)
        // table depends on RTT relative to rttMax (NACK Threshold)
        _protectionFactorD = static_cast<uint8_t>
                            (adjustRtt *
                             static_cast<float>(_protectionFactorD));
        // update FEC rates after applying adjustment
        VCMFecMethod::UpdateProtectionFactorD(_protectionFactorD);
    }

    return true;
}

int VCMNackFecMethod::ComputeMaxFramesFec(
    const VCMProtectionParameters* parameters) {
  if (parameters->numLayers > 2) {
    // For more than 2 temporal layers we will only have FEC on the base layer,
    // and the base layers will be pretty far apart. Therefore we force one
    // frame FEC.
    return 1;
  }
  // We set the max number of frames to base the FEC on so that on average
  // we will have complete frames in one RTT. Note that this is an upper
  // bound, and that the actual number of frames used for FEC is decided by the
  // RTP module based on the actual number of packets and the protection factor.
  float base_layer_framerate = parameters->frameRate /
      static_cast<float>(1 << (parameters->numLayers - 1));
  int max_frames_fec = std::max(static_cast<int>(
      2.0f * base_layer_framerate * parameters->rtt /
      1000.0f + 0.5f), 1);
  // |kUpperLimitFramesFec| is the upper limit on how many frames we
  // allow any FEC to be based on.
  if (max_frames_fec > kUpperLimitFramesFec) {
    max_frames_fec = kUpperLimitFramesFec;
  }
  return max_frames_fec;
}

int VCMNackFecMethod::MaxFramesFec() const {
  return _maxFramesFec;
}

bool VCMNackFecMethod::BitRateTooLowForFec(
    const VCMProtectionParameters* parameters) {
  // Bitrate below which we turn off FEC, regardless of reported packet loss.
  // The condition should depend on resolution and content. For now, use
  // threshold on bytes per frame, with some effect for the frame size.
  // The condition for turning off FEC is also based on other factors,
  // such as |_numLayers|, |_maxFramesFec|, and |_rtt|.
  int estimate_bytes_per_frame = 1000 * BitsPerFrame(parameters) / 8;
  int max_bytes_per_frame = kMaxBytesPerFrameForFec;
  int num_pixels = parameters->codecWidth * parameters->codecHeight;
  if (num_pixels <= 352 * 288) {
    max_bytes_per_frame = kMaxBytesPerFrameForFecLow;
  } else if (num_pixels > 640 * 480) {
    max_bytes_per_frame = kMaxBytesPerFrameForFecHigh;
  }
  // TODO (marpan): add condition based on maximum frames used for FEC,
  // and expand condition based on frame size.
  // Max round trip time threshold in ms.
  const int64_t kMaxRttTurnOffFec = 200;
  if (estimate_bytes_per_frame < max_bytes_per_frame &&
      parameters->numLayers < 3 &&
      parameters->rtt < kMaxRttTurnOffFec) {
    return true;
  }
  return false;
}

bool
VCMNackFecMethod::EffectivePacketLoss(const VCMProtectionParameters* parameters)
{
    // Set the effective packet loss for encoder (based on FEC code).
    // Compute the effective packet loss and residual packet loss due to FEC.
    VCMFecMethod::EffectivePacketLoss(parameters);
    return true;
}

bool
VCMNackFecMethod::UpdateParameters(const VCMProtectionParameters* parameters)
{
    ProtectionFactor(parameters);
    EffectivePacketLoss(parameters);
    _maxFramesFec = ComputeMaxFramesFec(parameters);
    if (BitRateTooLowForFec(parameters)) {
      _protectionFactorK = 0;
      _protectionFactorD = 0;
    }

    // Protection/fec rates obtained above are defined relative to total number
    // of packets (total rate: source + fec) FEC in RTP module assumes
    // protection factor is defined relative to source number of packets so we
    // should convert the factor to reduce mismatch between mediaOpt's rate and
    // the actual one
    _protectionFactorK = VCMFecMethod::ConvertFECRate(_protectionFactorK);
    _protectionFactorD = VCMFecMethod::ConvertFECRate(_protectionFactorD);

    return true;
}

VCMNackMethod::VCMNackMethod():
VCMProtectionMethod()
{
    _type = kNack;
}

VCMNackMethod::~VCMNackMethod()
{
    //
}

bool
VCMNackMethod::EffectivePacketLoss(const VCMProtectionParameters* parameter)
{
    // Effective Packet Loss, NA in current version.
    _effectivePacketLoss = 0;
    return true;
}

bool
VCMNackMethod::UpdateParameters(const VCMProtectionParameters* parameters)
{
    // Compute the effective packet loss
    EffectivePacketLoss(parameters);

    // nackCost  = (bitRate - nackCost) * (lossPr)
    return true;
}

VCMFecMethod::VCMFecMethod():
VCMProtectionMethod()
{
    _type = kFec;
}
VCMFecMethod::~VCMFecMethod()
{
    //
}

uint8_t
VCMFecMethod::BoostCodeRateKey(uint8_t packetFrameDelta,
                               uint8_t packetFrameKey) const
{
    uint8_t boostRateKey = 2;
    // Default: ratio scales the FEC protection up for I frames
    uint8_t ratio = 1;

    if (packetFrameDelta > 0)
    {
        ratio = (int8_t) (packetFrameKey / packetFrameDelta);
    }
    ratio = VCM_MAX(boostRateKey, ratio);

    return ratio;
}

uint8_t
VCMFecMethod::ConvertFECRate(uint8_t codeRateRTP) const
{
    return static_cast<uint8_t> (VCM_MIN(255,(0.5 + 255.0 * codeRateRTP /
                                      (float)(255 - codeRateRTP))));
}

// Update FEC with protectionFactorD
void
VCMFecMethod::UpdateProtectionFactorD(uint8_t protectionFactorD)
{
    _protectionFactorD = protectionFactorD;
}

// Update FEC with protectionFactorK
void
VCMFecMethod::UpdateProtectionFactorK(uint8_t protectionFactorK)
{
    _protectionFactorK = protectionFactorK;
}

bool
VCMFecMethod::ProtectionFactor(const VCMProtectionParameters* parameters)
{
    // FEC PROTECTION SETTINGS: varies with packet loss and bitrate

    // No protection if (filtered) packetLoss is 0
    uint8_t packetLoss = (uint8_t) (255 * parameters->lossPr);
    if (packetLoss == 0)
    {
        _protectionFactorK = 0;
        _protectionFactorD = 0;
         return true;
    }

    // Parameters for FEC setting:
    // first partition size, thresholds, table pars, spatial resoln fac.

    // First partition protection: ~ 20%
    uint8_t firstPartitionProt = (uint8_t) (255 * 0.20);

    // Minimum protection level needed to generate one FEC packet for one
    // source packet/frame (in RTP sender)
    uint8_t minProtLevelFec = 85;

    // Threshold on packetLoss and bitRrate/frameRate (=average #packets),
    // above which we allocate protection to cover at least first partition.
    uint8_t lossThr = 0;
    uint8_t packetNumThr = 1;

    // Parameters for range of rate index of table.
    const uint8_t ratePar1 = 5;
    const uint8_t ratePar2 = 49;

    // Spatial resolution size, relative to a reference size.
    float spatialSizeToRef = static_cast<float>
                           (parameters->codecWidth * parameters->codecHeight) /
                           (static_cast<float>(704 * 576));
    // resolnFac: This parameter will generally increase/decrease the FEC rate
    // (for fixed bitRate and packetLoss) based on system size.
    // Use a smaller exponent (< 1) to control/soften system size effect.
    const float resolnFac = 1.0 / powf(spatialSizeToRef, 0.3f);

    const int bitRatePerFrame = BitsPerFrame(parameters);


    // Average number of packets per frame (source and fec):
    const uint8_t avgTotPackets = 1 + (uint8_t)
                                        ((float) bitRatePerFrame * 1000.0
                                       / (float) (8.0 * _maxPayloadSize) + 0.5);

    // FEC rate parameters: for P and I frame
    uint8_t codeRateDelta = 0;
    uint8_t codeRateKey = 0;

    // Get index for table: the FEC protection depends on an effective rate.
    // The range on the rate index corresponds to rates (bps)
    // from ~200k to ~8000k, for 30fps
    const uint16_t effRateFecTable = static_cast<uint16_t>
                                           (resolnFac * bitRatePerFrame);
    uint8_t rateIndexTable =
        (uint8_t) VCM_MAX(VCM_MIN((effRateFecTable - ratePar1) /
                                         ratePar1, ratePar2), 0);

    // Restrict packet loss range to 50:
    // current tables defined only up to 50%
    if (packetLoss >= kPacketLossMax)
    {
        packetLoss = kPacketLossMax - 1;
    }
    uint16_t indexTable = rateIndexTable * kPacketLossMax + packetLoss;

    // Check on table index
    assert(indexTable < kSizeCodeRateXORTable);

    // Protection factor for P frame
    codeRateDelta = kCodeRateXORTable[indexTable];

    if (packetLoss > lossThr && avgTotPackets > packetNumThr)
    {
        // Set a minimum based on first partition size.
        if (codeRateDelta < firstPartitionProt)
        {
            codeRateDelta = firstPartitionProt;
        }
    }

    // Check limit on amount of protection for P frame; 50% is max.
    if (codeRateDelta >= kPacketLossMax)
    {
        codeRateDelta = kPacketLossMax - 1;
    }

    float adjustFec = 1.0f;
    // Avoid additional adjustments when layers are active.
    // TODO(mikhal/marco): Update adjusmtent based on layer info.
    if (parameters->numLayers == 1)
    {
        adjustFec = _qmRobustness->AdjustFecFactor(codeRateDelta,
                                                   parameters->bitRate,
                                                   parameters->frameRate,
                                                   parameters->rtt,
                                                   packetLoss);
    }

    codeRateDelta = static_cast<uint8_t>(codeRateDelta * adjustFec);

    // For Key frame:
    // Effectively at a higher rate, so we scale/boost the rate
    // The boost factor may depend on several factors: ratio of packet
    // number of I to P frames, how much protection placed on P frames, etc.
    const uint8_t packetFrameDelta = (uint8_t)
                                           (0.5 + parameters->packetsPerFrame);
    const uint8_t packetFrameKey = (uint8_t)
                                         (0.5 + parameters->packetsPerFrameKey);
    const uint8_t boostKey = BoostCodeRateKey(packetFrameDelta,
                                                    packetFrameKey);

    rateIndexTable = (uint8_t) VCM_MAX(VCM_MIN(
                      1 + (boostKey * effRateFecTable - ratePar1) /
                      ratePar1,ratePar2),0);
    uint16_t indexTableKey = rateIndexTable * kPacketLossMax + packetLoss;

    indexTableKey = VCM_MIN(indexTableKey, kSizeCodeRateXORTable);

    // Check on table index
    assert(indexTableKey < kSizeCodeRateXORTable);

    // Protection factor for I frame
    codeRateKey = kCodeRateXORTable[indexTableKey];

    // Boosting for Key frame.
    int boostKeyProt = _scaleProtKey * codeRateDelta;
    if (boostKeyProt >= kPacketLossMax)
    {
        boostKeyProt = kPacketLossMax - 1;
    }

    // Make sure I frame protection is at least larger than P frame protection,
    // and at least as high as filtered packet loss.
    codeRateKey = static_cast<uint8_t> (VCM_MAX(packetLoss,
            VCM_MAX(boostKeyProt, codeRateKey)));

    // Check limit on amount of protection for I frame: 50% is max.
    if (codeRateKey >= kPacketLossMax)
    {
        codeRateKey = kPacketLossMax - 1;
    }

    _protectionFactorK = codeRateKey;
    _protectionFactorD = codeRateDelta;

    // Generally there is a rate mis-match between the FEC cost estimated
    // in mediaOpt and the actual FEC cost sent out in RTP module.
    // This is more significant at low rates (small # of source packets), where
    // the granularity of the FEC decreases. In this case, non-zero protection
    // in mediaOpt may generate 0 FEC packets in RTP sender (since actual #FEC
    // is based on rounding off protectionFactor on actual source packet number).
    // The correction factor (_corrFecCost) attempts to corrects this, at least
    // for cases of low rates (small #packets) and low protection levels.

    float numPacketsFl = 1.0f + ((float) bitRatePerFrame * 1000.0
                                / (float) (8.0 * _maxPayloadSize) + 0.5);

    const float estNumFecGen = 0.5f + static_cast<float> (_protectionFactorD *
                                                         numPacketsFl / 255.0f);


    // We reduce cost factor (which will reduce overhead for FEC and
    // hybrid method) and not the protectionFactor.
    _corrFecCost = 1.0f;
    if (estNumFecGen < 1.1f && _protectionFactorD < minProtLevelFec)
    {
        _corrFecCost = 0.5f;
    }
    if (estNumFecGen < 0.9f && _protectionFactorD < minProtLevelFec)
    {
        _corrFecCost = 0.0f;
    }

     // TODO (marpan): Set the UEP protection on/off for Key and Delta frames
    _useUepProtectionK = _qmRobustness->SetUepProtection(codeRateKey,
                                                         parameters->bitRate,
                                                         packetLoss,
                                                         0);

    _useUepProtectionD = _qmRobustness->SetUepProtection(codeRateDelta,
                                                         parameters->bitRate,
                                                         packetLoss,
                                                         1);

    // DONE WITH FEC PROTECTION SETTINGS
    return true;
}

int VCMFecMethod::BitsPerFrame(const VCMProtectionParameters* parameters) {
  // When temporal layers are available FEC will only be applied on the base
  // layer.
  const float bitRateRatio =
    kVp8LayerRateAlloction[parameters->numLayers - 1][0];
  float frameRateRatio = powf(1 / 2.0, parameters->numLayers - 1);
  float bitRate = parameters->bitRate * bitRateRatio;
  float frameRate = parameters->frameRate * frameRateRatio;

  // TODO(mikhal): Update factor following testing.
  float adjustmentFactor = 1;

  // Average bits per frame (units of kbits)
  return static_cast<int>(adjustmentFactor * bitRate / frameRate);
}

bool
VCMFecMethod::EffectivePacketLoss(const VCMProtectionParameters* parameters)
{
    // Effective packet loss to encoder is based on RPL (residual packet loss)
    // this is a soft setting based on degree of FEC protection
    // RPL = received/input packet loss - average_FEC_recovery
    // note: received/input packet loss may be filtered based on FilteredLoss

    // Effective Packet Loss, NA in current version.
    _effectivePacketLoss = 0;

    return true;
}

bool
VCMFecMethod::UpdateParameters(const VCMProtectionParameters* parameters)
{
    // Compute the protection factor
    ProtectionFactor(parameters);

    // Compute the effective packet loss
    EffectivePacketLoss(parameters);

    // Protection/fec rates obtained above is defined relative to total number
    // of packets (total rate: source+fec) FEC in RTP module assumes protection
    // factor is defined relative to source number of packets so we should
    // convert the factor to reduce mismatch between mediaOpt suggested rate and
    // the actual rate
    _protectionFactorK = ConvertFECRate(_protectionFactorK);
    _protectionFactorD = ConvertFECRate(_protectionFactorD);

    return true;
}
VCMLossProtectionLogic::VCMLossProtectionLogic(int64_t nowMs):
_currentParameters(),
_rtt(0),
_lossPr(0.0f),
_bitRate(0.0f),
_frameRate(0.0f),
_keyFrameSize(0.0f),
_fecRateKey(0),
_fecRateDelta(0),
_lastPrUpdateT(0),
_lossPr255(0.9999f),
_lossPrHistory(),
_shortMaxLossPr255(0),
_packetsPerFrame(0.9999f),
_packetsPerFrameKey(0.9999f),
_codecWidth(0),
_codecHeight(0),
_numLayers(1)
{
    Reset(nowMs);
}

VCMLossProtectionLogic::~VCMLossProtectionLogic()
{
    Release();
}

void VCMLossProtectionLogic::SetMethod(
    enum VCMProtectionMethodEnum newMethodType) {
  if (_selectedMethod && _selectedMethod->Type() == newMethodType)
    return;

  switch(newMethodType) {
    case kNack:
      _selectedMethod.reset(new VCMNackMethod());
      break;
    case kFec:
      _selectedMethod.reset(new VCMFecMethod());
      break;
    case kNackFec:
      _selectedMethod.reset(new VCMNackFecMethod(kLowRttNackMs, -1));
      break;
    case kNone:
      _selectedMethod.reset();
      break;
  }
  UpdateMethod();
}

void
VCMLossProtectionLogic::UpdateRtt(int64_t rtt)
{
    _rtt = rtt;
}

void
VCMLossProtectionLogic::UpdateMaxLossHistory(uint8_t lossPr255,
                                             int64_t now)
{
    if (_lossPrHistory[0].timeMs >= 0 &&
        now - _lossPrHistory[0].timeMs < kLossPrShortFilterWinMs)
    {
        if (lossPr255 > _shortMaxLossPr255)
        {
            _shortMaxLossPr255 = lossPr255;
        }
    }
    else
    {
        // Only add a new value to the history once a second
        if (_lossPrHistory[0].timeMs == -1)
        {
            // First, no shift
            _shortMaxLossPr255 = lossPr255;
        }
        else
        {
            // Shift
            for (int32_t i = (kLossPrHistorySize - 2); i >= 0; i--)
            {
                _lossPrHistory[i + 1].lossPr255 = _lossPrHistory[i].lossPr255;
                _lossPrHistory[i + 1].timeMs = _lossPrHistory[i].timeMs;
            }
        }
        if (_shortMaxLossPr255 == 0)
        {
            _shortMaxLossPr255 = lossPr255;
        }

        _lossPrHistory[0].lossPr255 = _shortMaxLossPr255;
        _lossPrHistory[0].timeMs = now;
        _shortMaxLossPr255 = 0;
    }
}

uint8_t
VCMLossProtectionLogic::MaxFilteredLossPr(int64_t nowMs) const
{
    uint8_t maxFound = _shortMaxLossPr255;
    if (_lossPrHistory[0].timeMs == -1)
    {
        return maxFound;
    }
    for (int32_t i = 0; i < kLossPrHistorySize; i++)
    {
        if (_lossPrHistory[i].timeMs == -1)
        {
            break;
        }
        if (nowMs - _lossPrHistory[i].timeMs >
            kLossPrHistorySize * kLossPrShortFilterWinMs)
        {
            // This sample (and all samples after this) is too old
            break;
        }
        if (_lossPrHistory[i].lossPr255 > maxFound)
        {
            // This sample is the largest one this far into the history
            maxFound = _lossPrHistory[i].lossPr255;
        }
    }
    return maxFound;
}

uint8_t VCMLossProtectionLogic::FilteredLoss(
    int64_t nowMs,
    FilterPacketLossMode filter_mode,
    uint8_t lossPr255) {

  // Update the max window filter.
  UpdateMaxLossHistory(lossPr255, nowMs);

  // Update the recursive average filter.
  _lossPr255.Apply(static_cast<float> (nowMs - _lastPrUpdateT),
                   static_cast<float> (lossPr255));
  _lastPrUpdateT = nowMs;

  // Filtered loss: default is received loss (no filtering).
  uint8_t filtered_loss = lossPr255;

  switch (filter_mode) {
    case kNoFilter:
      break;
    case kAvgFilter:
      filtered_loss = static_cast<uint8_t>(_lossPr255.filtered() + 0.5);
      break;
    case kMaxFilter:
      filtered_loss = MaxFilteredLossPr(nowMs);
      break;
  }

  return filtered_loss;
}

void
VCMLossProtectionLogic::UpdateFilteredLossPr(uint8_t packetLossEnc)
{
    _lossPr = (float) packetLossEnc / (float) 255.0;
}

void
VCMLossProtectionLogic::UpdateBitRate(float bitRate)
{
    _bitRate = bitRate;
}

void
VCMLossProtectionLogic::UpdatePacketsPerFrame(float nPackets, int64_t nowMs)
{
    _packetsPerFrame.Apply(static_cast<float>(nowMs - _lastPacketPerFrameUpdateT),
                           nPackets);
    _lastPacketPerFrameUpdateT = nowMs;
}

void
VCMLossProtectionLogic::UpdatePacketsPerFrameKey(float nPackets, int64_t nowMs)
{
    _packetsPerFrameKey.Apply(static_cast<float>(nowMs -
                              _lastPacketPerFrameUpdateTKey), nPackets);
    _lastPacketPerFrameUpdateTKey = nowMs;
}

void
VCMLossProtectionLogic::UpdateKeyFrameSize(float keyFrameSize)
{
    _keyFrameSize = keyFrameSize;
}

void
VCMLossProtectionLogic::UpdateFrameSize(uint16_t width,
                                        uint16_t height)
{
    _codecWidth = width;
    _codecHeight = height;
}

void VCMLossProtectionLogic::UpdateNumLayers(int numLayers) {
  _numLayers = (numLayers == 0) ? 1 : numLayers;
}

bool
VCMLossProtectionLogic::UpdateMethod()
{
    if (!_selectedMethod)
      return false;
    _currentParameters.rtt = _rtt;
    _currentParameters.lossPr = _lossPr;
    _currentParameters.bitRate = _bitRate;
    _currentParameters.frameRate = _frameRate; // rename actual frame rate?
    _currentParameters.keyFrameSize = _keyFrameSize;
    _currentParameters.fecRateDelta = _fecRateDelta;
    _currentParameters.fecRateKey = _fecRateKey;
    _currentParameters.packetsPerFrame = _packetsPerFrame.filtered();
    _currentParameters.packetsPerFrameKey = _packetsPerFrameKey.filtered();
    _currentParameters.codecWidth = _codecWidth;
    _currentParameters.codecHeight = _codecHeight;
    _currentParameters.numLayers = _numLayers;
    return _selectedMethod->UpdateParameters(&_currentParameters);
}

VCMProtectionMethod*
VCMLossProtectionLogic::SelectedMethod() const
{
    return _selectedMethod.get();
}

VCMProtectionMethodEnum VCMLossProtectionLogic::SelectedType() const {
  return _selectedMethod ? _selectedMethod->Type() : kNone;
}

void
VCMLossProtectionLogic::Reset(int64_t nowMs)
{
    _lastPrUpdateT = nowMs;
    _lastPacketPerFrameUpdateT = nowMs;
    _lastPacketPerFrameUpdateTKey = nowMs;
    _lossPr255.Reset(0.9999f);
    _packetsPerFrame.Reset(0.9999f);
    _fecRateDelta = _fecRateKey = 0;
    for (int32_t i = 0; i < kLossPrHistorySize; i++)
    {
        _lossPrHistory[i].lossPr255 = 0;
        _lossPrHistory[i].timeMs = -1;
    }
    _shortMaxLossPr255 = 0;
    Release();
}

void VCMLossProtectionLogic::Release() {
  _selectedMethod.reset();
}

}  // namespace media_optimization
}  // namespace webrtc