summaryrefslogtreecommitdiffstats
path: root/dom/media/platforms/agnostic/AOMDecoder.cpp
blob: 284c209d51530076a754acd602aa1f1a6ad89360 (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
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "AOMDecoder.h"

#include <algorithm>

#include "BitWriter.h"
#include "BitReader.h"
#include "ImageContainer.h"
#include "MediaResult.h"
#include "TimeUnits.h"
#include <aom/aom_image.h>
#include <aom/aomdx.h>
#include "gfx2DGlue.h"
#include "gfxUtils.h"
#include "mozilla/PodOperations.h"
#include "mozilla/SyncRunnable.h"
#include "mozilla/TaskQueue.h"
#include "nsError.h"
#include "nsThreadUtils.h"
#include "prsystem.h"
#include "VideoUtils.h"

#undef LOG
#define LOG(arg, ...)                                                  \
  DDMOZ_LOG(sPDMLog, mozilla::LogLevel::Debug, "::%s: " arg, __func__, \
            ##__VA_ARGS__)
#define LOG_RESULT(code, message, ...)                                        \
  DDMOZ_LOG(sPDMLog, mozilla::LogLevel::Debug, "::%s: %s (code %d) " message, \
            __func__, aom_codec_err_to_string(code), (int)code, ##__VA_ARGS__)
#define LOGEX_RESULT(_this, code, message, ...)         \
  DDMOZ_LOGEX(_this, sPDMLog, mozilla::LogLevel::Debug, \
              "::%s: %s (code %d) " message, __func__,  \
              aom_codec_err_to_string(code), (int)code, ##__VA_ARGS__)
#define LOG_STATIC_RESULT(code, message, ...)                 \
  MOZ_LOG(sPDMLog, mozilla::LogLevel::Debug,                  \
          ("AOMDecoder::%s: %s (code %d) " message, __func__, \
           aom_codec_err_to_string(code), (int)code, ##__VA_ARGS__))

#define ASSERT_BYTE_ALIGNED(bitIO) MOZ_ASSERT((bitIO).BitCount() % 8 == 0)

namespace mozilla {

using namespace gfx;
using namespace layers;
using gfx::CICP::ColourPrimaries;
using gfx::CICP::MatrixCoefficients;
using gfx::CICP::TransferCharacteristics;

static MediaResult InitContext(AOMDecoder& aAOMDecoder, aom_codec_ctx_t* aCtx,
                               const VideoInfo& aInfo) {
  aom_codec_iface_t* dx = aom_codec_av1_dx();
  if (!dx) {
    return MediaResult(NS_ERROR_DOM_MEDIA_FATAL_ERR,
                       RESULT_DETAIL("Couldn't get AV1 decoder interface."));
  }

  size_t decode_threads = 2;
  if (aInfo.mDisplay.width >= 2048) {
    decode_threads = 8;
  } else if (aInfo.mDisplay.width >= 1024) {
    decode_threads = 4;
  }
  decode_threads = std::min(decode_threads, GetNumberOfProcessors());

  aom_codec_dec_cfg_t config;
  PodZero(&config);
  config.threads = static_cast<unsigned int>(decode_threads);
  config.w = config.h = 0;  // set after decode
  config.allow_lowbitdepth = true;

  aom_codec_flags_t flags = 0;

  auto res = aom_codec_dec_init(aCtx, dx, &config, flags);
  if (res != AOM_CODEC_OK) {
    LOGEX_RESULT(&aAOMDecoder, res, "Codec initialization failed, res=%d",
                 int(res));
    return MediaResult(NS_ERROR_DOM_MEDIA_FATAL_ERR,
                       RESULT_DETAIL("AOM error initializing AV1 decoder: %s",
                                     aom_codec_err_to_string(res)));
  }
  return NS_OK;
}

AOMDecoder::AOMDecoder(const CreateDecoderParams& aParams)
    : mImageContainer(aParams.mImageContainer),
      mTaskQueue(TaskQueue::Create(
          GetMediaThreadPool(MediaThreadType::PLATFORM_DECODER), "AOMDecoder")),
      mInfo(aParams.VideoConfig()),
      mTrackingId(aParams.mTrackingId) {
  PodZero(&mCodec);
}

AOMDecoder::~AOMDecoder() = default;

RefPtr<ShutdownPromise> AOMDecoder::Shutdown() {
  RefPtr<AOMDecoder> self = this;
  return InvokeAsync(mTaskQueue, __func__, [self]() {
    auto res = aom_codec_destroy(&self->mCodec);
    if (res != AOM_CODEC_OK) {
      LOGEX_RESULT(self.get(), res, "aom_codec_destroy");
    }
    return self->mTaskQueue->BeginShutdown();
  });
}

RefPtr<MediaDataDecoder::InitPromise> AOMDecoder::Init() {
  MediaResult rv = InitContext(*this, &mCodec, mInfo);
  if (NS_FAILED(rv)) {
    return AOMDecoder::InitPromise::CreateAndReject(rv, __func__);
  }
  return AOMDecoder::InitPromise::CreateAndResolve(TrackInfo::kVideoTrack,
                                                   __func__);
}

RefPtr<MediaDataDecoder::FlushPromise> AOMDecoder::Flush() {
  return InvokeAsync(mTaskQueue, __func__, [this, self = RefPtr(this)]() {
    mPerformanceRecorder.Record(std::numeric_limits<int64_t>::max());
    return FlushPromise::CreateAndResolve(true, __func__);
  });
}

// UniquePtr dtor wrapper for aom_image_t.
struct AomImageFree {
  void operator()(aom_image_t* img) { aom_img_free(img); }
};

RefPtr<MediaDataDecoder::DecodePromise> AOMDecoder::ProcessDecode(
    MediaRawData* aSample) {
  MOZ_ASSERT(mTaskQueue->IsCurrentThreadIn());

#if defined(DEBUG)
  NS_ASSERTION(
      IsKeyframe(*aSample) == aSample->mKeyframe,
      "AOM Decode Keyframe error sample->mKeyframe and si.si_kf out of sync");
#endif

  MediaInfoFlag flag = MediaInfoFlag::None;
  flag |= (aSample->mKeyframe ? MediaInfoFlag::KeyFrame
                              : MediaInfoFlag::NonKeyFrame);
  flag |= MediaInfoFlag::SoftwareDecoding;
  flag |= MediaInfoFlag::VIDEO_AV1;

  mTrackingId.apply([&](const auto& aId) {
    mPerformanceRecorder.Start(aSample->mTimecode.ToMicroseconds(),
                               "AOMDecoder"_ns, aId, flag);
  });

  if (aom_codec_err_t r = aom_codec_decode(&mCodec, aSample->Data(),
                                           aSample->Size(), nullptr)) {
    LOG_RESULT(r, "Decode error!");
    return DecodePromise::CreateAndReject(
        MediaResult(NS_ERROR_DOM_MEDIA_DECODE_ERR,
                    RESULT_DETAIL("AOM error decoding AV1 sample: %s",
                                  aom_codec_err_to_string(r))),
        __func__);
  }

  aom_codec_iter_t iter = nullptr;
  aom_image_t* img;
  UniquePtr<aom_image_t, AomImageFree> img8;
  DecodedData results;

  while ((img = aom_codec_get_frame(&mCodec, &iter))) {
    NS_ASSERTION(
        img->fmt == AOM_IMG_FMT_I420 || img->fmt == AOM_IMG_FMT_I42016 ||
            img->fmt == AOM_IMG_FMT_I444 || img->fmt == AOM_IMG_FMT_I44416,
        "AV1 image format not I420 or I444");

    // Chroma shifts are rounded down as per the decoding examples in the SDK
    VideoData::YCbCrBuffer b;
    b.mPlanes[0].mData = img->planes[0];
    b.mPlanes[0].mStride = img->stride[0];
    b.mPlanes[0].mHeight = img->d_h;
    b.mPlanes[0].mWidth = img->d_w;
    b.mPlanes[0].mSkip = 0;

    b.mPlanes[1].mData = img->planes[1];
    b.mPlanes[1].mStride = img->stride[1];
    b.mPlanes[1].mSkip = 0;

    b.mPlanes[2].mData = img->planes[2];
    b.mPlanes[2].mStride = img->stride[2];
    b.mPlanes[2].mSkip = 0;

    if (img->fmt == AOM_IMG_FMT_I420 || img->fmt == AOM_IMG_FMT_I42016) {
      b.mChromaSubsampling = gfx::ChromaSubsampling::HALF_WIDTH_AND_HEIGHT;

      b.mPlanes[1].mHeight = (img->d_h + 1) >> img->y_chroma_shift;
      b.mPlanes[1].mWidth = (img->d_w + 1) >> img->x_chroma_shift;

      b.mPlanes[2].mHeight = (img->d_h + 1) >> img->y_chroma_shift;
      b.mPlanes[2].mWidth = (img->d_w + 1) >> img->x_chroma_shift;
    } else if (img->fmt == AOM_IMG_FMT_I444 || img->fmt == AOM_IMG_FMT_I44416) {
      b.mPlanes[1].mHeight = img->d_h;
      b.mPlanes[1].mWidth = img->d_w;

      b.mPlanes[2].mHeight = img->d_h;
      b.mPlanes[2].mWidth = img->d_w;
    } else {
      LOG("AOM Unknown image format");
      return DecodePromise::CreateAndReject(
          MediaResult(NS_ERROR_DOM_MEDIA_DECODE_ERR,
                      RESULT_DETAIL("AOM Unknown image format")),
          __func__);
    }

    if (img->bit_depth == 10) {
      b.mColorDepth = ColorDepth::COLOR_10;
    } else if (img->bit_depth == 12) {
      b.mColorDepth = ColorDepth::COLOR_12;
    }

    switch (img->mc) {
      case AOM_CICP_MC_BT_601:
        b.mYUVColorSpace = YUVColorSpace::BT601;
        break;
      case AOM_CICP_MC_BT_2020_NCL:
      case AOM_CICP_MC_BT_2020_CL:
        b.mYUVColorSpace = YUVColorSpace::BT2020;
        break;
      case AOM_CICP_MC_BT_709:
        b.mYUVColorSpace = YUVColorSpace::BT709;
        break;
      default:
        b.mYUVColorSpace = DefaultColorSpace({img->d_w, img->d_h});
        break;
    }
    b.mColorRange = img->range == AOM_CR_FULL_RANGE ? ColorRange::FULL
                                                    : ColorRange::LIMITED;

    switch (img->cp) {
      case AOM_CICP_CP_BT_709:
        b.mColorPrimaries = ColorSpace2::BT709;
        break;
      case AOM_CICP_CP_BT_2020:
        b.mColorPrimaries = ColorSpace2::BT2020;
        break;
      default:
        b.mColorPrimaries = ColorSpace2::BT709;
        break;
    }

    Result<already_AddRefed<VideoData>, MediaResult> r =
        VideoData::CreateAndCopyData(
            mInfo, mImageContainer, aSample->mOffset, aSample->mTime,
            aSample->mDuration, b, aSample->mKeyframe, aSample->mTimecode,
            mInfo.ScaledImageRect(img->d_w, img->d_h), nullptr);

    if (r.isErr()) {
      MediaResult rs = r.unwrapErr();
      LOG("VideoData::CreateAndCopyData error (source %ux%u display %ux%u "
          "picture %ux%u)  - %s: %s",
          img->d_w, img->d_h, mInfo.mDisplay.width, mInfo.mDisplay.height,
          mInfo.mImage.width, mInfo.mImage.height, rs.ErrorName().get(),
          rs.Message().get());

      return DecodePromise::CreateAndReject(std::move(rs), __func__);
    }

    RefPtr<VideoData> v = r.unwrap();
    MOZ_ASSERT(v);

    mPerformanceRecorder.Record(
        aSample->mTimecode.ToMicroseconds(), [&](DecodeStage& aStage) {
          aStage.SetResolution(mInfo.mImage.width, mInfo.mImage.height);
          auto format = [&]() -> Maybe<DecodeStage::ImageFormat> {
            switch (img->fmt) {
              case AOM_IMG_FMT_I420:
              case AOM_IMG_FMT_I42016:
                return Some(DecodeStage::YUV420P);
              case AOM_IMG_FMT_I444:
              case AOM_IMG_FMT_I44416:
                return Some(DecodeStage::YUV444P);
              default:
                return Nothing();
            }
          }();
          format.apply([&](auto& aFmt) { aStage.SetImageFormat(aFmt); });
          aStage.SetYUVColorSpace(b.mYUVColorSpace);
          aStage.SetColorRange(b.mColorRange);
          aStage.SetColorDepth(b.mColorDepth);
          aStage.SetStartTimeAndEndTime(v->mTime.ToMicroseconds(),
                                        v->GetEndTime().ToMicroseconds());
        });
    results.AppendElement(std::move(v));
  }
  return DecodePromise::CreateAndResolve(std::move(results), __func__);
}

RefPtr<MediaDataDecoder::DecodePromise> AOMDecoder::Decode(
    MediaRawData* aSample) {
  return InvokeAsync<MediaRawData*>(mTaskQueue, this, __func__,
                                    &AOMDecoder::ProcessDecode, aSample);
}

RefPtr<MediaDataDecoder::DecodePromise> AOMDecoder::Drain() {
  return InvokeAsync(mTaskQueue, __func__, [] {
    return DecodePromise::CreateAndResolve(DecodedData(), __func__);
  });
}

/* static */
bool AOMDecoder::IsAV1(const nsACString& aMimeType) {
  return aMimeType.EqualsLiteral("video/av1");
}

/* static */
bool AOMDecoder::IsKeyframe(Span<const uint8_t> aBuffer) {
  aom_codec_stream_info_t info;
  PodZero(&info);

  auto res = aom_codec_peek_stream_info(aom_codec_av1_dx(), aBuffer.Elements(),
                                        aBuffer.Length(), &info);
  if (res != AOM_CODEC_OK) {
    LOG_STATIC_RESULT(
        res, "couldn't get keyframe flag with aom_codec_peek_stream_info");
    return false;
  }

  return bool(info.is_kf);
}

/* static */
gfx::IntSize AOMDecoder::GetFrameSize(Span<const uint8_t> aBuffer) {
  aom_codec_stream_info_t info;
  PodZero(&info);

  auto res = aom_codec_peek_stream_info(aom_codec_av1_dx(), aBuffer.Elements(),
                                        aBuffer.Length(), &info);
  if (res != AOM_CODEC_OK) {
    LOG_STATIC_RESULT(
        res, "couldn't get frame size with aom_codec_peek_stream_info");
  }

  return gfx::IntSize(info.w, info.h);
}

/* static */
AOMDecoder::OBUIterator AOMDecoder::ReadOBUs(const Span<const uint8_t>& aData) {
  return OBUIterator(aData);
}

void AOMDecoder::OBUIterator::UpdateNext() {
  // If mGoNext is not set, we don't need to load a new OBU.
  if (!mGoNext) {
    return;
  }
  // Check if we've reached the end of the data. Allow mGoNext to stay true so
  // that HasNext() will return false.
  if (mPosition >= mData.Length()) {
    return;
  }
  mGoNext = false;

  // If retrieving the next OBU fails, reset the current OBU and set the
  // position past the end of the data so that HasNext() returns false.
  auto resetExit = MakeScopeExit([&]() {
    mCurrent = OBUInfo();
    mPosition = mData.Length();
  });

  auto subspan = mData.Subspan(mPosition, mData.Length() - mPosition);
  BitReader br(subspan.Elements(), subspan.Length() * 8);
  OBUInfo temp;

  // AV1 spec available at:
  // https://aomediacodec.github.io/av1-spec/
  // or https://aomediacodec.github.io/av1-spec/av1-spec.pdf

  // begin open_bitstream_unit( )
  // https://aomediacodec.github.io/av1-spec/#general-obu-syntax

  // begin obu_header( )
  // https://aomediacodec.github.io/av1-spec/#obu-header-syntax
  br.ReadBit();  // obu_forbidden_bit
  temp.mType = static_cast<OBUType>(br.ReadBits(4));
  if (!temp.IsValid()) {
    // Non-fatal error, unknown OBUs can be skipped as long as the size field
    // is properly specified.
    NS_WARNING(nsPrintfCString("Encountered unknown OBU type (%" PRIu8
                               ", OBU may be invalid",
                               static_cast<uint8_t>(temp.mType))
                   .get());
  }
  temp.mExtensionFlag = br.ReadBit();
  bool hasSizeField = br.ReadBit();
  br.ReadBit();  // obu_reserved_1bit

  // begin obu_extension_header( ) (5.3.3)
  if (temp.mExtensionFlag) {
    if (br.BitsLeft() < 8) {
      mResult = MediaResult(NS_ERROR_DOM_MEDIA_DECODE_ERR,
                            "Not enough bits left for an OBU extension header");
      return;
    }
    br.ReadBits(3);  // temporal_id
    br.ReadBits(2);  // spatial_id
    br.ReadBits(3);  // extension_header_reserved_3bits
  }
  // end obu_extension_header( )
  // end obu_header( )

  // Get the size of the remaining OBU data attached to the header in
  // bytes.
  size_t size;
  if (hasSizeField) {
    if (br.BitsLeft() < 8) {
      mResult = MediaResult(NS_ERROR_DOM_MEDIA_DECODE_ERR,
                            "Not enough bits left for an OBU size field");
      return;
    }
    CheckedUint32 checkedSize = br.ReadULEB128().toChecked<uint32_t>();
    // Spec requires that the value ULEB128 reads is (1 << 32) - 1 or below.
    // See leb128(): https://aomediacodec.github.io/av1-spec/#leb128
    if (!checkedSize.isValid()) {
      mResult =
          MediaResult(NS_ERROR_DOM_MEDIA_DECODE_ERR, "OBU size was too large");
      return;
    }
    size = checkedSize.value();
  } else {
    // This case should rarely happen in practice. To support the Annex B
    // format in the specification, we would have to parse every header type
    // to skip over them, but this allows us to at least iterate once to
    // retrieve the first OBU in the data.
    size = mData.Length() - 1 - temp.mExtensionFlag;
  }

  if (br.BitsLeft() / 8 < size) {
    mResult = MediaResult(
        NS_ERROR_DOM_MEDIA_DECODE_ERR,
        nsPrintfCString("Size specified by the OBU header (%zu) is more "
                        "than the actual remaining OBU data (%zu)",
                        size, br.BitsLeft() / 8)
            .get());
    return;
  }

  ASSERT_BYTE_ALIGNED(br);

  size_t bytes = br.BitCount() / 8;
  temp.mContents = mData.Subspan(mPosition + bytes, size);
  mCurrent = temp;
  // end open_bitstream_unit( )

  mPosition += bytes + size;
  resetExit.release();
  mResult = NS_OK;
}

/* static */
already_AddRefed<MediaByteBuffer> AOMDecoder::CreateOBU(
    const OBUType aType, const Span<const uint8_t>& aContents) {
  RefPtr<MediaByteBuffer> buffer = new MediaByteBuffer();

  BitWriter bw(buffer);
  bw.WriteBits(0, 1);  // obu_forbidden_bit
  bw.WriteBits(static_cast<uint8_t>(aType), 4);
  bw.WriteBit(false);  // obu_extension_flag
  bw.WriteBit(true);   // obu_has_size_field
  bw.WriteBits(0, 1);  // obu_reserved_1bit
  ASSERT_BYTE_ALIGNED(bw);
  bw.WriteULEB128(aContents.Length());
  ASSERT_BYTE_ALIGNED(bw);

  buffer->AppendElements(aContents.Elements(), aContents.Length());
  return buffer.forget();
}

/* static */
MediaResult AOMDecoder::ReadSequenceHeaderInfo(
    const Span<const uint8_t>& aSample, AV1SequenceInfo& aDestInfo) {
  // We need to get the last sequence header OBU, the specification does not
  // limit a temporal unit to one sequence header.
  OBUIterator iter = ReadOBUs(aSample);
  OBUInfo seqOBU;

  while (true) {
    if (!iter.HasNext()) {
      // Pass along the error from parsing the OBU.
      MediaResult result = iter.GetResult();
      if (result.Code() != NS_OK) {
        return result;
      }
      break;
    }
    OBUInfo obu = iter.Next();
    if (obu.mType == OBUType::SequenceHeader) {
      seqOBU = obu;
    }
  }

  if (seqOBU.mType != OBUType::SequenceHeader) {
    return NS_ERROR_DOM_MEDIA_WAITING_FOR_DATA;
  }

  // Sequence header syntax is specified here:
  // https://aomediacodec.github.io/av1-spec/#sequence-header-obu-syntax
  // Section 5.5: Sequence header OBU syntax

  // See also Section 6.4: Sequence header OBU semantics
  // https://aomediacodec.github.io/av1-spec/#sequence-header-obu-semantics
  // This section defines all the fields used in the sequence header.
  BitReader br(seqOBU.mContents.Elements(), seqOBU.mContents.Length() * 8);
  AV1SequenceInfo tempInfo;

  // begin sequence_header_obu( )
  // https://aomediacodec.github.io/av1-spec/#general-sequence-header-obu-syntax
  tempInfo.mProfile = br.ReadBits(3);
  const bool stillPicture = br.ReadBit();
  const bool reducedStillPicture = br.ReadBit();
  if (!stillPicture && reducedStillPicture) {
    return MediaResult(
        NS_ERROR_DOM_MEDIA_DECODE_ERR,
        "reduced_still_picture is true while still_picture is false");
  }

  if (reducedStillPicture) {
    OperatingPoint op;
    op.mLayers = 0;
    op.mLevel = br.ReadBits(5);  // seq_level_idx[0]
    op.mTier = 0;
    tempInfo.mOperatingPoints.SetCapacity(1);
    tempInfo.mOperatingPoints.AppendElement(op);
  } else {
    bool decoderModelInfoPresent;
    uint8_t operatingPointCountMinusOne;

    if (br.ReadBit()) {  // timing_info_present_flag
      // begin timing_info( )
      // https://aomediacodec.github.io/av1-spec/#timing-info-syntax
      br.ReadBits(32);     // num_units_in_display_tick
      br.ReadBits(32);     // time_scale
      if (br.ReadBit()) {  // equal_picture_interval
        br.ReadUE();       // num_ticks_per_picture_minus_1
      }
      // end timing_info( )

      decoderModelInfoPresent = br.ReadBit();
      if (decoderModelInfoPresent) {
        // begin decoder_model_info( )
        // https://aomediacodec.github.io/av1-spec/#decoder-model-info-syntax
        br.ReadBits(5);   // buffer_delay_length_minus_1
        br.ReadBits(32);  // num_units_in_decoding_tick
        br.ReadBits(5);   // buffer_removal_time_length_minus_1
        br.ReadBits(5);   // frame_presentation_time_length_minus_1
        // end decoder_model_info( )
      }
    } else {
      decoderModelInfoPresent = false;
    }

    bool initialDisplayDelayPresent = br.ReadBit();
    operatingPointCountMinusOne = br.ReadBits(5);
    tempInfo.mOperatingPoints.SetCapacity(operatingPointCountMinusOne + 1);
    for (uint8_t i = 0; i <= operatingPointCountMinusOne; i++) {
      OperatingPoint op;
      op.mLayers = br.ReadBits(12);  // operating_point_idc[ i ]
      op.mLevel = br.ReadBits(5);    // seq_level_idx[ i ]
      op.mTier = op.mLevel > 7 ? br.ReadBits(1) : 0;
      if (decoderModelInfoPresent) {
        br.ReadBit();  // decoder_model_present_for_this_op[ i ]
      }
      if (initialDisplayDelayPresent) {
        if (br.ReadBit()) {  // initial_display_delay_present_for_this_op[ i ]
          br.ReadBits(4);
        }
      }
      tempInfo.mOperatingPoints.AppendElement(op);
    }
  }

  uint8_t frameWidthBits = br.ReadBits(4) + 1;
  uint8_t frameHeightBits = br.ReadBits(4) + 1;
  uint32_t maxWidth = br.ReadBits(frameWidthBits) + 1;
  uint32_t maxHeight = br.ReadBits(frameHeightBits) + 1;
  tempInfo.mImage = gfx::IntSize(maxWidth, maxHeight);

  if (!reducedStillPicture) {
    if (br.ReadBit()) {  // frame_id_numbers_present_flag
      br.ReadBits(4);    // delta_frame_id_length_minus_2
      br.ReadBits(3);    // additional_frame_id_legnth_minus_1
    }
  }

  br.ReadBit();  // use_128x128_superblock
  br.ReadBit();  // enable_filter_intra
  br.ReadBit();  // enable_intra_edge_filter

  if (reducedStillPicture) {
    // enable_interintra_compound = 0
    // enable_masked_compound = 0
    // enable_warped_motion = 0
    // enable_dual_filter = 0
    // enable_order_hint = 0
    // enable_jnt_comp = 0
    // enable_ref_frame_mvs = 0
    // seq_force_screen_content_tools = SELECT_SCREEN_CONTENT_TOOLS
    // seq_force_integer_mv = SELECT_INTEGER_MV
    // OrderHintBits = 0
  } else {
    br.ReadBit();  // enable_interintra_compound
    br.ReadBit();  // enable_masked_compound
    br.ReadBit();  // enable_warped_motion
    br.ReadBit();  // enable_dual_filter

    const bool enableOrderHint = br.ReadBit();

    if (enableOrderHint) {
      br.ReadBit();  // enable_jnt_comp
      br.ReadBit();  // enable_ref_frame_mvs
    }

    uint8_t forceScreenContentTools;

    if (br.ReadBit()) {             // seq_choose_screen_content_tools
      forceScreenContentTools = 2;  // SELECT_SCREEN_CONTENT_TOOLS
    } else {
      forceScreenContentTools = br.ReadBits(1);
    }

    if (forceScreenContentTools > 0) {
      if (!br.ReadBit()) {  // seq_choose_integer_mv
        br.ReadBit();       // seq_force_integer_mv
      }
    }

    if (enableOrderHint) {
      br.ReadBits(3);  // order_hint_bits_minus_1
    }
  }

  br.ReadBit();  // enable_superres
  br.ReadBit();  // enable_cdef
  br.ReadBit();  // enable_restoration

  // begin color_config( )
  // https://aomediacodec.github.io/av1-spec/#color-config-syntax
  const bool highBitDepth = br.ReadBit();
  if (tempInfo.mProfile == 2 && highBitDepth) {
    const bool twelveBit = br.ReadBit();
    tempInfo.mBitDepth = twelveBit ? 12 : 10;
  } else {
    tempInfo.mBitDepth = highBitDepth ? 10 : 8;
  }

  tempInfo.mMonochrome = tempInfo.mProfile == 1 ? false : br.ReadBit();

  VideoColorSpace* colors = &tempInfo.mColorSpace;

  if (br.ReadBit()) {  // color_description_present_flag
    colors->mPrimaries = static_cast<ColourPrimaries>(br.ReadBits(8));
    colors->mTransfer = static_cast<TransferCharacteristics>(br.ReadBits(8));
    colors->mMatrix = static_cast<MatrixCoefficients>(br.ReadBits(8));
  } else {
    colors->mPrimaries = ColourPrimaries::CP_UNSPECIFIED;
    colors->mTransfer = TransferCharacteristics::TC_UNSPECIFIED;
    colors->mMatrix = MatrixCoefficients::MC_UNSPECIFIED;
  }

  if (tempInfo.mMonochrome) {
    colors->mRange = br.ReadBit() ? ColorRange::FULL : ColorRange::LIMITED;
    tempInfo.mSubsamplingX = true;
    tempInfo.mSubsamplingY = true;
    tempInfo.mChromaSamplePosition = ChromaSamplePosition::Unknown;
  } else if (colors->mPrimaries == ColourPrimaries::CP_BT709 &&
             colors->mTransfer == TransferCharacteristics::TC_SRGB &&
             colors->mMatrix == MatrixCoefficients::MC_IDENTITY) {
    colors->mRange = ColorRange::FULL;
    tempInfo.mSubsamplingX = false;
    tempInfo.mSubsamplingY = false;
  } else {
    colors->mRange = br.ReadBit() ? ColorRange::FULL : ColorRange::LIMITED;
    switch (tempInfo.mProfile) {
      case 0:
        tempInfo.mSubsamplingX = true;
        tempInfo.mSubsamplingY = true;
        break;
      case 1:
        tempInfo.mSubsamplingX = false;
        tempInfo.mSubsamplingY = false;
        break;
      case 2:
        if (tempInfo.mBitDepth == 12) {
          tempInfo.mSubsamplingX = br.ReadBit();
          tempInfo.mSubsamplingY =
              tempInfo.mSubsamplingX ? br.ReadBit() : false;
        } else {
          tempInfo.mSubsamplingX = true;
          tempInfo.mSubsamplingY = false;
        }
        break;
    }
    tempInfo.mChromaSamplePosition =
        tempInfo.mSubsamplingX && tempInfo.mSubsamplingY
            ? static_cast<ChromaSamplePosition>(br.ReadBits(2))
            : ChromaSamplePosition::Unknown;
  }

  br.ReadBit();  // separate_uv_delta_q
  // end color_config( )

  br.ReadBit();  // film_grain_params_present
  // end sequence_header_obu( )

  // begin trailing_bits( )
  // https://aomediacodec.github.io/av1-spec/#trailing-bits-syntax
  if (br.BitsLeft() > 8) {
    NS_WARNING(
        "AV1 sequence header finished reading with more than "
        "a byte of aligning bits, may indicate an error");
  }
  // Ensure that data is read correctly by checking trailing bits.
  bool correct = br.ReadBit();
  correct &= br.ReadBits(br.BitsLeft() % 8) == 0;
  while (br.BitsLeft() > 0) {
    correct &= br.ReadBits(8) == 0;
  }
  if (!correct) {
    return MediaResult(NS_ERROR_DOM_MEDIA_DECODE_ERR,
                       "AV1 sequence header was corrupted");
  }
  // end trailing_bits( )

  aDestInfo = tempInfo;
  return NS_OK;
}

/* static */
already_AddRefed<MediaByteBuffer> AOMDecoder::CreateSequenceHeader(
    const AV1SequenceInfo& aInfo, nsresult& aResult) {
  aResult = NS_ERROR_FAILURE;

  RefPtr<MediaByteBuffer> seqHdrBuffer = new MediaByteBuffer();
  BitWriter bw(seqHdrBuffer);

  // See 5.5.1: General sequence header OBU syntax
  // https://aomediacodec.github.io/av1-spec/#general-sequence-header-obu-syntax
  bw.WriteBits(aInfo.mProfile, 3);
  bw.WriteBit(false);  // still_picture
  bw.WriteBit(false);  // reduced_still_picture_header

  bw.WriteBit(false);  // timing_info_present_flag
  // if ( timing_info_present_flag ) {...}
  bw.WriteBit(false);  // initial_display_delay_present_flag

  size_t opCount = aInfo.mOperatingPoints.Length();
  bw.WriteBits(opCount - 1, 5);  // operating_points_cnt_minus_1
  for (size_t i = 0; i < opCount; i++) {
    OperatingPoint op = aInfo.mOperatingPoints[i];
    bw.WriteBits(op.mLayers, 12);  // operating_point_idc[ i ]
    bw.WriteBits(op.mLevel, 5);
    if (op.mLevel > 7) {
      bw.WriteBits(op.mTier, 1);
    } else {
      // seq_tier[ i ] = 0
      if (op.mTier != 0) {
        NS_WARNING("Operating points cannot specify tier for levels under 8.");
        return nullptr;
      }
    }
    // if ( decoder_model_info_present_flag ) {...}
    // else
    //   decoder_model_info_present_for_this_op[ i ] = 0
    // if ( initial_display_delay_present_flag ) {...}
  }

  if (aInfo.mImage.IsEmpty()) {
    NS_WARNING("Sequence header requires a valid image size");
    return nullptr;
  }
  auto getBits = [](int32_t value) {
    uint8_t bit = 0;
    do {
      value >>= 1;
      bit++;
    } while (value > 0);
    return bit;
  };
  uint8_t bitsW = getBits(aInfo.mImage.Width());
  uint8_t bitsH = getBits(aInfo.mImage.Height());
  bw.WriteBits(bitsW - 1, 4);
  bw.WriteBits(bitsH - 1, 4);
  bw.WriteBits(aInfo.mImage.Width() - 1, bitsW);
  bw.WriteBits(aInfo.mImage.Height() - 1, bitsH);

  // if ( !reduced_still_picture_header )
  bw.WriteBit(false);  // frame_id_numbers_present_flag
  // if ( frame_id_numbers_present_flag ) {...}
  // end if ( !reduced_still_picture_header )

  // Values below are derived from a 1080p YouTube AV1 stream.
  // The values are unused currently for determining the usable
  // decoder, and are only included to allow successful validation
  // of the generated sequence header.

  bw.WriteBit(true);  // use_128x128_superblock
  bw.WriteBit(true);  // enable_filter_intra
  bw.WriteBit(true);  // enable_intra_edge_filter

  // if ( !reduced_still_picture_header)
  bw.WriteBit(false);  // enable_interintra_compound
  bw.WriteBit(true);   // enable_masked_compound
  bw.WriteBit(true);   // enable_warped_motion
  bw.WriteBit(false);  // enable_dual_filter

  bw.WriteBit(true);  // enable_order_hint
  // if ( enable_order_hint )
  bw.WriteBit(false);  // enable_jnt_comp
  bw.WriteBit(true);   // enable_ref_frame_mvs
  // end if ( enable_order_hint )

  bw.WriteBit(true);  // seq_choose_screen_content_tools
  // if ( seq_choose_screen_content_tools )
  //   seq_force_screen_content_tools = SELECT_SCREEN_CONTENT_TOOLS (2)
  // else
  //   seq_force_screen_content_tools = f(1)

  // if ( seq_force_screen_content_tools > 0 )
  bw.WriteBit(true);  // seq_choose_integer_mv
  // if ( !seq_choose_integer_mv ) {...}
  // end if ( seq_force_screen_content_tools > 0 )

  // if ( enable_order_hint )
  bw.WriteBits(6, 3);  // order_hint_bits_minus_1
  // end if ( enable_order_hint )
  // end if ( !reduced_still_picture_header )

  bw.WriteBit(false);  // enable_superres
  bw.WriteBit(false);  // enable_cdef
  bw.WriteBit(true);   // enable_restoration

  // Begin color_config( )
  // https://aomediacodec.github.io/av1-spec/#color-config-syntax
  bool highBitDepth = aInfo.mBitDepth >= 10;
  bw.WriteBit(highBitDepth);

  if (aInfo.mBitDepth == 12 && aInfo.mProfile != 2) {
    NS_WARNING("Profile must be 2 for 12-bit");
    return nullptr;
  }
  if (aInfo.mProfile == 2 && highBitDepth) {
    bw.WriteBit(aInfo.mBitDepth == 12);  // twelve_bit
  }

  if (aInfo.mMonochrome && aInfo.mProfile == 1) {
    NS_WARNING("Profile 1 does not support monochrome");
    return nullptr;
  }
  if (aInfo.mProfile != 1) {
    bw.WriteBit(aInfo.mMonochrome);
  }

  const VideoColorSpace colors = aInfo.mColorSpace;
  bool colorsPresent =
      colors.mPrimaries != ColourPrimaries::CP_UNSPECIFIED ||
      colors.mTransfer != TransferCharacteristics::TC_UNSPECIFIED ||
      colors.mMatrix != MatrixCoefficients::MC_UNSPECIFIED;
  bw.WriteBit(colorsPresent);

  if (colorsPresent) {
    bw.WriteBits(static_cast<uint8_t>(colors.mPrimaries), 8);
    bw.WriteBits(static_cast<uint8_t>(colors.mTransfer), 8);
    bw.WriteBits(static_cast<uint8_t>(colors.mMatrix), 8);
  }

  if (aInfo.mMonochrome) {
    if (!aInfo.mSubsamplingX || !aInfo.mSubsamplingY) {
      NS_WARNING("Monochrome requires 4:0:0 subsampling");
      return nullptr;
    }
    if (aInfo.mChromaSamplePosition != ChromaSamplePosition::Unknown) {
      NS_WARNING(
          "Cannot specify chroma sample position on monochrome sequence");
      return nullptr;
    }
    bw.WriteBit(colors.mRange == ColorRange::FULL);
  } else if (colors.mPrimaries == ColourPrimaries::CP_BT709 &&
             colors.mTransfer == TransferCharacteristics::TC_SRGB &&
             colors.mMatrix == MatrixCoefficients::MC_IDENTITY) {
    if (aInfo.mSubsamplingX || aInfo.mSubsamplingY ||
        colors.mRange != ColorRange::FULL ||
        aInfo.mChromaSamplePosition != ChromaSamplePosition::Unknown) {
      NS_WARNING("sRGB requires 4:4:4 subsampling with full color range");
      return nullptr;
    }
  } else {
    bw.WriteBit(colors.mRange == ColorRange::FULL);
    switch (aInfo.mProfile) {
      case 0:
        if (!aInfo.mSubsamplingX || !aInfo.mSubsamplingY) {
          NS_WARNING("Main Profile requires 4:2:0 subsampling");
          return nullptr;
        }
        break;
      case 1:
        if (aInfo.mSubsamplingX || aInfo.mSubsamplingY) {
          NS_WARNING("High Profile requires 4:4:4 subsampling");
          return nullptr;
        }
        break;
      case 2:
        if (aInfo.mBitDepth == 12) {
          bw.WriteBit(aInfo.mSubsamplingX);
          if (aInfo.mSubsamplingX) {
            bw.WriteBit(aInfo.mSubsamplingY);
          }
        } else {
          if (!aInfo.mSubsamplingX || aInfo.mSubsamplingY) {
            NS_WARNING(
                "Professional Profile < 12-bit requires 4:2:2 subsampling");
            return nullptr;
          }
        }
        break;
    }

    if (aInfo.mSubsamplingX && aInfo.mSubsamplingY) {
      bw.WriteBits(static_cast<uint8_t>(aInfo.mChromaSamplePosition), 2);
    } else {
      if (aInfo.mChromaSamplePosition != ChromaSamplePosition::Unknown) {
        NS_WARNING("Only 4:2:0 subsampling can specify chroma position");
        return nullptr;
      }
    }
  }

  bw.WriteBit(false);  // separate_uv_delta_q
  // end color_config( )

  bw.WriteBit(true);  // film_grain_params_present

  // trailing_bits( )
  // https://aomediacodec.github.io/av1-spec/#trailing-bits-syntax
  size_t numTrailingBits = 8 - (bw.BitCount() % 8);
  bw.WriteBit(true);
  bw.WriteBits(0, numTrailingBits - 1);
  ASSERT_BYTE_ALIGNED(bw);

  Span<const uint8_t> seqHdr(seqHdrBuffer->Elements(), seqHdrBuffer->Length());
  aResult = NS_OK;
  return CreateOBU(OBUType::SequenceHeader, seqHdr);
}

/* static */
void AOMDecoder::TryReadAV1CBox(const MediaByteBuffer* aBox,
                                AV1SequenceInfo& aDestInfo,
                                MediaResult& aSeqHdrResult) {
  // See av1C specification:
  // https://aomediacodec.github.io/av1-isobmff/#av1codecconfigurationbox-section
  BitReader br(aBox);

  br.ReadBits(8);  // marker, version

  aDestInfo.mProfile = br.ReadBits(3);

  OperatingPoint op;
  op.mLevel = br.ReadBits(5);
  op.mTier = br.ReadBits(1);
  aDestInfo.mOperatingPoints.AppendElement(op);

  bool highBitDepth = br.ReadBit();
  bool twelveBit = br.ReadBit();
  aDestInfo.mBitDepth = highBitDepth ? twelveBit ? 12 : 10 : 8;

  aDestInfo.mMonochrome = br.ReadBit();
  aDestInfo.mSubsamplingX = br.ReadBit();
  aDestInfo.mSubsamplingY = br.ReadBit();
  aDestInfo.mChromaSamplePosition =
      static_cast<ChromaSamplePosition>(br.ReadBits(2));

  br.ReadBits(3);  // reserved
  br.ReadBit();    // initial_presentation_delay_present
  br.ReadBits(4);  // initial_presentation_delay_minus_one or reserved

  ASSERT_BYTE_ALIGNED(br);

  size_t skipBytes = br.BitCount() / 8;
  Span<const uint8_t> obus(aBox->Elements() + skipBytes,
                           aBox->Length() - skipBytes);

  // Minimum possible OBU header size
  if (obus.Length() < 1) {
    aSeqHdrResult = NS_ERROR_DOM_MEDIA_WAITING_FOR_DATA;
    return;
  }

  // If present, the sequence header will be redundant to some values, but any
  // values stored in it should be treated as more accurate than av1C.
  aSeqHdrResult = ReadSequenceHeaderInfo(obus, aDestInfo);
}

/* static */
void AOMDecoder::WriteAV1CBox(const AV1SequenceInfo& aInfo,
                              MediaByteBuffer* aDestBox, bool& aHasSeqHdr) {
  aHasSeqHdr = false;

  BitWriter bw(aDestBox);

  bw.WriteBit(true);   // marker
  bw.WriteBits(1, 7);  // version

  bw.WriteBits(aInfo.mProfile, 3);

  MOZ_DIAGNOSTIC_ASSERT(aInfo.mOperatingPoints.Length() > 0);
  bw.WriteBits(aInfo.mOperatingPoints[0].mLevel, 5);
  bw.WriteBits(aInfo.mOperatingPoints[0].mTier, 1);

  bw.WriteBit(aInfo.mBitDepth >= 10);  // high_bitdepth
  bw.WriteBit(aInfo.mBitDepth == 12);  // twelve_bit

  bw.WriteBit(aInfo.mMonochrome);
  bw.WriteBit(aInfo.mSubsamplingX);
  bw.WriteBit(aInfo.mSubsamplingY);
  bw.WriteBits(static_cast<uint8_t>(aInfo.mChromaSamplePosition), 2);

  bw.WriteBits(0, 3);  // reserved
  bw.WriteBit(false);  // initial_presentation_delay_present
  bw.WriteBits(0, 4);  // initial_presentation_delay_minus_one or reserved

  ASSERT_BYTE_ALIGNED(bw);

  nsresult rv;
  RefPtr<MediaByteBuffer> seqHdrBuffer = CreateSequenceHeader(aInfo, rv);

  if (NS_SUCCEEDED(rv)) {
    aDestBox->AppendElements(seqHdrBuffer->Elements(), seqHdrBuffer->Length());
    aHasSeqHdr = true;
  }
}

/* static */
Maybe<AOMDecoder::AV1SequenceInfo> AOMDecoder::CreateSequenceInfoFromCodecs(
    const nsAString& aCodec) {
  AV1SequenceInfo info;
  OperatingPoint op;
  uint8_t chromaSamplePosition;
  if (!ExtractAV1CodecDetails(aCodec, info.mProfile, op.mLevel, op.mTier,
                              info.mBitDepth, info.mMonochrome,
                              info.mSubsamplingX, info.mSubsamplingY,
                              chromaSamplePosition, info.mColorSpace)) {
    return Nothing();
  }
  info.mOperatingPoints.AppendElement(op);
  info.mChromaSamplePosition =
      static_cast<ChromaSamplePosition>(chromaSamplePosition);
  return Some(info);
}

/* static */
bool AOMDecoder::SetVideoInfo(VideoInfo* aDestInfo, const nsAString& aCodec) {
  Maybe<AV1SequenceInfo> info = CreateSequenceInfoFromCodecs(aCodec);
  if (info.isNothing()) {
    return false;
  }

  if (!aDestInfo->mImage.IsEmpty()) {
    info->mImage = aDestInfo->mImage;
  }

  RefPtr<MediaByteBuffer> extraData = new MediaByteBuffer();
  bool hasSeqHdr;
  WriteAV1CBox(info.value(), extraData, hasSeqHdr);
  aDestInfo->mExtraData = extraData;
  return true;
}

}  // namespace mozilla
#undef LOG
#undef ASSERT_BYTE_ALIGNED