-
Notifications
You must be signed in to change notification settings - Fork 2.6k
/
mp4-tools.ts
1145 lines (1045 loc) · 33.3 KB
/
mp4-tools.ts
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
import { ElementaryStreamTypes } from '../loader/fragment';
import { sliceUint8 } from './typed-array';
import { utf8ArrayToStr } from '../demux/id3';
import { logger } from '../utils/logger';
import Hex from './hex';
import type { PassthroughTrack, UserdataSample } from '../types/demuxer';
import type { DecryptData } from '../loader/level-key';
const UINT32_MAX = Math.pow(2, 32) - 1;
const push = [].push;
// We are using fixed track IDs for driving the MP4 remuxer
// instead of following the TS PIDs.
// There is no reason not to do this and some browsers/SourceBuffer-demuxers
// may not like if there are TrackID "switches"
// See https://github.com/video-dev/hls.js/issues/1331
// Here we are mapping our internal track types to constant MP4 track IDs
// With MSE currently one can only have one track of each, and we are muxing
// whatever video/audio rendition in them.
export const RemuxerTrackIdConfig = {
video: 1,
audio: 2,
id3: 3,
text: 4,
};
export function bin2str(data: Uint8Array): string {
return String.fromCharCode.apply(null, data);
}
export function readUint16(buffer: Uint8Array, offset: number): number {
const val = (buffer[offset] << 8) | buffer[offset + 1];
return val < 0 ? 65536 + val : val;
}
export function readUint32(buffer: Uint8Array, offset: number): number {
const val = readSint32(buffer, offset);
return val < 0 ? 4294967296 + val : val;
}
export function readSint32(buffer: Uint8Array, offset: number): number {
return (
(buffer[offset] << 24) |
(buffer[offset + 1] << 16) |
(buffer[offset + 2] << 8) |
buffer[offset + 3]
);
}
export function writeUint32(buffer: Uint8Array, offset: number, value: number) {
buffer[offset] = value >> 24;
buffer[offset + 1] = (value >> 16) & 0xff;
buffer[offset + 2] = (value >> 8) & 0xff;
buffer[offset + 3] = value & 0xff;
}
// Find the data for a box specified by its path
export function findBox(data: Uint8Array, path: string[]): Uint8Array[] {
const results = [] as Uint8Array[];
if (!path.length) {
// short-circuit the search for empty paths
return results;
}
const end = data.byteLength;
for (let i = 0; i < end; ) {
const size = readUint32(data, i);
const type = bin2str(data.subarray(i + 4, i + 8));
const endbox = size > 1 ? i + size : end;
if (type === path[0]) {
if (path.length === 1) {
// this is the end of the path and we've found the box we were
// looking for
results.push(data.subarray(i + 8, endbox));
} else {
// recursively search for the next box along the path
const subresults = findBox(data.subarray(i + 8, endbox), path.slice(1));
if (subresults.length) {
push.apply(results, subresults);
}
}
}
i = endbox;
}
// we've finished searching all of data
return results;
}
type SidxInfo = {
earliestPresentationTime: number;
timescale: number;
version: number;
referencesCount: number;
references: any[];
};
export function parseSegmentIndex(sidx: Uint8Array): SidxInfo | null {
const references: any[] = [];
const version = sidx[0];
// set initial offset, we skip the reference ID (not needed)
let index = 8;
const timescale = readUint32(sidx, index);
index += 4;
// TODO: parse earliestPresentationTime and firstOffset
// usually zero in our case
const earliestPresentationTime = 0;
const firstOffset = 0;
if (version === 0) {
index += 8;
} else {
index += 16;
}
// skip reserved
index += 2;
let startByte = sidx.length + firstOffset;
const referencesCount = readUint16(sidx, index);
index += 2;
for (let i = 0; i < referencesCount; i++) {
let referenceIndex = index;
const referenceInfo = readUint32(sidx, referenceIndex);
referenceIndex += 4;
const referenceSize = referenceInfo & 0x7fffffff;
const referenceType = (referenceInfo & 0x80000000) >>> 31;
if (referenceType === 1) {
// eslint-disable-next-line no-console
console.warn('SIDX has hierarchical references (not supported)');
return null;
}
const subsegmentDuration = readUint32(sidx, referenceIndex);
referenceIndex += 4;
references.push({
referenceSize,
subsegmentDuration, // unscaled
info: {
duration: subsegmentDuration / timescale,
start: startByte,
end: startByte + referenceSize - 1,
},
});
startByte += referenceSize;
// Skipping 1 bit for |startsWithSap|, 3 bits for |sapType|, and 28 bits
// for |sapDelta|.
referenceIndex += 4;
// skip to next ref
index = referenceIndex;
}
return {
earliestPresentationTime,
timescale,
version,
referencesCount,
references,
};
}
/**
* Parses an MP4 initialization segment and extracts stream type and
* timescale values for any declared tracks. Timescale values indicate the
* number of clock ticks per second to assume for time-based values
* elsewhere in the MP4.
*
* To determine the start time of an MP4, you need two pieces of
* information: the timescale unit and the earliest base media decode
* time. Multiple timescales can be specified within an MP4 but the
* base media decode time is always expressed in the timescale from
* the media header box for the track:
* ```
* moov > trak > mdia > mdhd.timescale
* moov > trak > mdia > hdlr
* ```
* @param initSegment {Uint8Array} the bytes of the init segment
* @return {InitData} a hash of track type to timescale values or null if
* the init segment is malformed.
*/
export interface InitDataTrack {
timescale: number;
id: number;
codec: string;
}
type HdlrType = ElementaryStreamTypes.AUDIO | ElementaryStreamTypes.VIDEO;
export interface InitData extends Array<any> {
[index: number]:
| {
timescale: number;
type: HdlrType;
default?: {
duration: number;
flags: number;
};
}
| undefined;
audio?: InitDataTrack;
video?: InitDataTrack;
caption?: InitDataTrack;
}
export function parseInitSegment(initSegment: Uint8Array): InitData {
const result: InitData = [];
const traks = findBox(initSegment, ['moov', 'trak']);
for (let i = 0; i < traks.length; i++) {
const trak = traks[i];
const tkhd = findBox(trak, ['tkhd'])[0];
if (tkhd) {
let version = tkhd[0];
let index = version === 0 ? 12 : 20;
const trackId = readUint32(tkhd, index);
const mdhd = findBox(trak, ['mdia', 'mdhd'])[0];
if (mdhd) {
version = mdhd[0];
index = version === 0 ? 12 : 20;
const timescale = readUint32(mdhd, index);
const hdlr = findBox(trak, ['mdia', 'hdlr'])[0];
if (hdlr) {
const hdlrType = bin2str(hdlr.subarray(8, 12));
const type: HdlrType | undefined = {
soun: ElementaryStreamTypes.AUDIO as const,
vide: ElementaryStreamTypes.VIDEO as const,
}[hdlrType];
if (type) {
// Parse codec details
const stsd = findBox(trak, ['mdia', 'minf', 'stbl', 'stsd'])[0];
let codec;
if (stsd) {
codec = bin2str(stsd.subarray(12, 16));
// TODO: Parse codec details to be able to build MIME type.
// stsd.start += 8;
// const codecBox = findBox(stsd, [codec])[0];
// if (codecBox) {
// TODO: Codec parsing support for avc1, mp4a, hevc, av01...
// }
}
result[trackId] = { timescale, type };
result[type] = { timescale, id: trackId, codec };
}
}
}
}
}
const trex = findBox(initSegment, ['moov', 'mvex', 'trex']);
trex.forEach((trex) => {
const trackId = readUint32(trex, 4);
const track = result[trackId];
if (track) {
track.default = {
duration: readUint32(trex, 12),
flags: readUint32(trex, 20),
};
}
});
return result;
}
export function patchEncyptionData(
initSegment: Uint8Array | undefined,
decryptdata: DecryptData | null
): Uint8Array | undefined {
if (!initSegment || !decryptdata) {
return initSegment;
}
const keyId = decryptdata.keyId;
if (keyId && decryptdata.isCommonEncryption) {
const traks = findBox(initSegment, ['moov', 'trak']);
traks.forEach((trak) => {
const stsd = findBox(trak, ['mdia', 'minf', 'stbl', 'stsd'])[0];
// skip the sample entry count
const sampleEntries = stsd.subarray(8);
let encBoxes = findBox(sampleEntries, ['enca']);
const isAudio = encBoxes.length > 0;
if (!isAudio) {
encBoxes = findBox(sampleEntries, ['encv']);
}
encBoxes.forEach((enc) => {
const encBoxChildren = isAudio ? enc.subarray(28) : enc.subarray(78);
const sinfBoxes = findBox(encBoxChildren, ['sinf']);
sinfBoxes.forEach((sinf) => {
const tenc = parseSinf(sinf);
if (tenc) {
// Look for default key id (keyID offset is always 8 within the tenc box):
const tencKeyId = tenc.subarray(8, 24);
if (!tencKeyId.some((b) => b !== 0)) {
logger.log(
`[eme] Patching keyId in 'enc${
isAudio ? 'a' : 'v'
}>sinf>>tenc' box: ${Hex.hexDump(tencKeyId)} -> ${Hex.hexDump(
keyId
)}`
);
tenc.set(keyId, 8);
}
}
});
});
});
}
return initSegment;
}
export function parseSinf(sinf: Uint8Array): Uint8Array | null {
const schm = findBox(sinf, ['schm'])[0];
if (schm) {
const scheme = bin2str(schm.subarray(4, 8));
if (scheme === 'cbcs' || scheme === 'cenc') {
return findBox(sinf, ['schi', 'tenc'])[0];
}
}
logger.error(`[eme] missing 'schm' box`);
return null;
}
/**
* Determine the base media decode start time, in seconds, for an MP4
* fragment. If multiple fragments are specified, the earliest time is
* returned.
*
* The base media decode time can be parsed from track fragment
* metadata:
* ```
* moof > traf > tfdt.baseMediaDecodeTime
* ```
* It requires the timescale value from the mdhd to interpret.
*
* @param initData {InitData} a hash of track type to timescale values
* @param fmp4 {Uint8Array} the bytes of the mp4 fragment
* @return {number} the earliest base media decode start time for the
* fragment, in seconds
*/
export function getStartDTS(initData: InitData, fmp4: Uint8Array): number {
// we need info from two children of each track fragment box
return (
findBox(fmp4, ['moof', 'traf']).reduce((result: number | null, traf) => {
const tfdt = findBox(traf, ['tfdt'])[0];
const version = tfdt[0];
const start = findBox(traf, ['tfhd']).reduce(
(result: number | null, tfhd) => {
// get the track id from the tfhd
const id = readUint32(tfhd, 4);
const track = initData[id];
if (track) {
let baseTime = readUint32(tfdt, 4);
if (version === 1) {
baseTime *= Math.pow(2, 32);
baseTime += readUint32(tfdt, 8);
}
// assume a 90kHz clock if no timescale was specified
const scale = track.timescale || 90e3;
// convert base time to seconds
const startTime = baseTime / scale;
if (
isFinite(startTime) &&
(result === null || startTime < result)
) {
return startTime;
}
}
return result;
},
null
);
if (
start !== null &&
isFinite(start) &&
(result === null || start < result)
) {
return start;
}
return result;
}, null) || 0
);
}
/*
For Reference:
aligned(8) class TrackFragmentHeaderBox
extends FullBox(‘tfhd’, 0, tf_flags){
unsigned int(32) track_ID;
// all the following are optional fields
unsigned int(64) base_data_offset;
unsigned int(32) sample_description_index;
unsigned int(32) default_sample_duration;
unsigned int(32) default_sample_size;
unsigned int(32) default_sample_flags
}
*/
export function getDuration(data: Uint8Array, initData: InitData) {
let rawDuration = 0;
let videoDuration = 0;
let audioDuration = 0;
const trafs = findBox(data, ['moof', 'traf']);
for (let i = 0; i < trafs.length; i++) {
const traf = trafs[i];
// There is only one tfhd & trun per traf
// This is true for CMAF style content, and we should perhaps check the ftyp
// and only look for a single trun then, but for ISOBMFF we should check
// for multiple track runs.
const tfhd = findBox(traf, ['tfhd'])[0];
// get the track id from the tfhd
const id = readUint32(tfhd, 4);
const track = initData[id];
if (!track) {
continue;
}
const trackDefault = track.default;
const tfhdFlags = readUint32(tfhd, 0) | trackDefault?.flags!;
let sampleDuration: number | undefined = trackDefault?.duration;
if (tfhdFlags & 0x000008) {
// 0x000008 indicates the presence of the default_sample_duration field
if (tfhdFlags & 0x000002) {
// 0x000002 indicates the presence of the sample_description_index field, which precedes default_sample_duration
// If present, the default_sample_duration exists at byte offset 12
sampleDuration = readUint32(tfhd, 12);
} else {
// Otherwise, the duration is at byte offset 8
sampleDuration = readUint32(tfhd, 8);
}
}
// assume a 90kHz clock if no timescale was specified
const timescale = track.timescale || 90e3;
const truns = findBox(traf, ['trun']);
for (let j = 0; j < truns.length; j++) {
rawDuration = computeRawDurationFromSamples(truns[j]);
if (!rawDuration && sampleDuration) {
const sampleCount = readUint32(truns[j], 4);
rawDuration = sampleDuration * sampleCount;
}
if (track.type === ElementaryStreamTypes.VIDEO) {
videoDuration += rawDuration / timescale;
} else if (track.type === ElementaryStreamTypes.AUDIO) {
audioDuration += rawDuration / timescale;
}
}
}
if (videoDuration === 0 && audioDuration === 0) {
// If duration samples are not available in the traf use sidx subsegment_duration
let sidxDuration = 0;
const sidxs = findBox(data, ['sidx']);
for (let i = 0; i < sidxs.length; i++) {
const sidx = parseSegmentIndex(sidxs[i]);
if (sidx?.references) {
sidxDuration += sidx.references.reduce(
(dur, ref) => dur + ref.info.duration || 0,
0
);
}
}
return sidxDuration;
}
if (videoDuration) {
return videoDuration;
}
return audioDuration;
}
/*
For Reference:
aligned(8) class TrackRunBox
extends FullBox(‘trun’, version, tr_flags) {
unsigned int(32) sample_count;
// the following are optional fields
signed int(32) data_offset;
unsigned int(32) first_sample_flags;
// all fields in the following array are optional
{
unsigned int(32) sample_duration;
unsigned int(32) sample_size;
unsigned int(32) sample_flags
if (version == 0)
{ unsigned int(32)
else
{ signed int(32)
}[ sample_count ]
}
*/
export function computeRawDurationFromSamples(trun): number {
const flags = readUint32(trun, 0);
// Flags are at offset 0, non-optional sample_count is at offset 4. Therefore we start 8 bytes in.
// Each field is an int32, which is 4 bytes
let offset = 8;
// data-offset-present flag
if (flags & 0x000001) {
offset += 4;
}
// first-sample-flags-present flag
if (flags & 0x000004) {
offset += 4;
}
let duration = 0;
const sampleCount = readUint32(trun, 4);
for (let i = 0; i < sampleCount; i++) {
// sample-duration-present flag
if (flags & 0x000100) {
const sampleDuration = readUint32(trun, offset);
duration += sampleDuration;
offset += 4;
}
// sample-size-present flag
if (flags & 0x000200) {
offset += 4;
}
// sample-flags-present flag
if (flags & 0x000400) {
offset += 4;
}
// sample-composition-time-offsets-present flag
if (flags & 0x000800) {
offset += 4;
}
}
return duration;
}
export function offsetStartDTS(
initData: InitData,
fmp4: Uint8Array,
timeOffset: number
) {
findBox(fmp4, ['moof', 'traf']).forEach((traf) => {
findBox(traf, ['tfhd']).forEach((tfhd) => {
// get the track id from the tfhd
const id = readUint32(tfhd, 4);
const track = initData[id];
if (!track) {
return;
}
// assume a 90kHz clock if no timescale was specified
const timescale = track.timescale || 90e3;
// get the base media decode time from the tfdt
findBox(traf, ['tfdt']).forEach((tfdt) => {
const version = tfdt[0];
let baseMediaDecodeTime = readUint32(tfdt, 4);
if (version === 0) {
baseMediaDecodeTime -= timeOffset * timescale;
baseMediaDecodeTime = Math.max(baseMediaDecodeTime, 0);
writeUint32(tfdt, 4, baseMediaDecodeTime);
} else {
baseMediaDecodeTime *= Math.pow(2, 32);
baseMediaDecodeTime += readUint32(tfdt, 8);
baseMediaDecodeTime -= timeOffset * timescale;
baseMediaDecodeTime = Math.max(baseMediaDecodeTime, 0);
const upper = Math.floor(baseMediaDecodeTime / (UINT32_MAX + 1));
const lower = Math.floor(baseMediaDecodeTime % (UINT32_MAX + 1));
writeUint32(tfdt, 4, upper);
writeUint32(tfdt, 8, lower);
}
});
});
});
}
// TODO: Check if the last moof+mdat pair is part of the valid range
export function segmentValidRange(data: Uint8Array): SegmentedRange {
const segmentedRange: SegmentedRange = {
valid: null,
remainder: null,
};
const moofs = findBox(data, ['moof']);
if (!moofs) {
return segmentedRange;
} else if (moofs.length < 2) {
segmentedRange.remainder = data;
return segmentedRange;
}
const last = moofs[moofs.length - 1];
// Offset by 8 bytes; findBox offsets the start by as much
segmentedRange.valid = sliceUint8(data, 0, last.byteOffset - 8);
segmentedRange.remainder = sliceUint8(data, last.byteOffset - 8);
return segmentedRange;
}
export interface SegmentedRange {
valid: Uint8Array | null;
remainder: Uint8Array | null;
}
export function appendUint8Array(
data1: Uint8Array,
data2: Uint8Array
): Uint8Array {
const temp = new Uint8Array(data1.length + data2.length);
temp.set(data1);
temp.set(data2, data1.length);
return temp;
}
export interface IEmsgParsingData {
schemeIdUri: string;
value: string;
timeScale: number;
presentationTimeDelta?: number;
presentationTime?: number;
eventDuration: number;
id: number;
payload: Uint8Array;
}
export function parseSamples(
timeOffset: number,
track: PassthroughTrack
): UserdataSample[] {
const seiSamples = [] as UserdataSample[];
const videoData = track.samples;
const timescale = track.timescale;
const trackId = track.id;
let isHEVCFlavor = false;
const moofs = findBox(videoData, ['moof']);
moofs.map((moof) => {
const moofOffset = moof.byteOffset - 8;
const trafs = findBox(moof, ['traf']);
trafs.map((traf) => {
// get the base media decode time from the tfdt
const baseTime = findBox(traf, ['tfdt']).map((tfdt) => {
const version = tfdt[0];
let result = readUint32(tfdt, 4);
if (version === 1) {
result *= Math.pow(2, 32);
result += readUint32(tfdt, 8);
}
return result / timescale;
})[0];
if (baseTime !== undefined) {
timeOffset = baseTime;
}
return findBox(traf, ['tfhd']).map((tfhd) => {
const id = readUint32(tfhd, 4);
const tfhdFlags = readUint32(tfhd, 0) & 0xffffff;
const baseDataOffsetPresent = (tfhdFlags & 0x000001) !== 0;
const sampleDescriptionIndexPresent = (tfhdFlags & 0x000002) !== 0;
const defaultSampleDurationPresent = (tfhdFlags & 0x000008) !== 0;
let defaultSampleDuration = 0;
const defaultSampleSizePresent = (tfhdFlags & 0x000010) !== 0;
let defaultSampleSize = 0;
const defaultSampleFlagsPresent = (tfhdFlags & 0x000020) !== 0;
let tfhdOffset = 8;
if (id === trackId) {
if (baseDataOffsetPresent) {
tfhdOffset += 8;
}
if (sampleDescriptionIndexPresent) {
tfhdOffset += 4;
}
if (defaultSampleDurationPresent) {
defaultSampleDuration = readUint32(tfhd, tfhdOffset);
tfhdOffset += 4;
}
if (defaultSampleSizePresent) {
defaultSampleSize = readUint32(tfhd, tfhdOffset);
tfhdOffset += 4;
}
if (defaultSampleFlagsPresent) {
tfhdOffset += 4;
}
if (track.type === 'video') {
isHEVCFlavor = isHEVC(track.codec);
}
findBox(traf, ['trun']).map((trun) => {
const version = trun[0];
const flags = readUint32(trun, 0) & 0xffffff;
const dataOffsetPresent = (flags & 0x000001) !== 0;
let dataOffset = 0;
const firstSampleFlagsPresent = (flags & 0x000004) !== 0;
const sampleDurationPresent = (flags & 0x000100) !== 0;
let sampleDuration = 0;
const sampleSizePresent = (flags & 0x000200) !== 0;
let sampleSize = 0;
const sampleFlagsPresent = (flags & 0x000400) !== 0;
const sampleCompositionOffsetsPresent = (flags & 0x000800) !== 0;
let compositionOffset = 0;
const sampleCount = readUint32(trun, 4);
let trunOffset = 8; // past version, flags, and sample count
if (dataOffsetPresent) {
dataOffset = readUint32(trun, trunOffset);
trunOffset += 4;
}
if (firstSampleFlagsPresent) {
trunOffset += 4;
}
let sampleOffset = dataOffset + moofOffset;
for (let ix = 0; ix < sampleCount; ix++) {
if (sampleDurationPresent) {
sampleDuration = readUint32(trun, trunOffset);
trunOffset += 4;
} else {
sampleDuration = defaultSampleDuration;
}
if (sampleSizePresent) {
sampleSize = readUint32(trun, trunOffset);
trunOffset += 4;
} else {
sampleSize = defaultSampleSize;
}
if (sampleFlagsPresent) {
trunOffset += 4;
}
if (sampleCompositionOffsetsPresent) {
if (version === 0) {
compositionOffset = readUint32(trun, trunOffset);
} else {
compositionOffset = readSint32(trun, trunOffset);
}
trunOffset += 4;
}
if (track.type === ElementaryStreamTypes.VIDEO) {
let naluTotalSize = 0;
while (naluTotalSize < sampleSize) {
const naluSize = readUint32(videoData, sampleOffset);
sampleOffset += 4;
if (isSEIMessage(isHEVCFlavor, videoData[sampleOffset])) {
const data = videoData.subarray(
sampleOffset,
sampleOffset + naluSize
);
parseSEIMessageFromNALu(
data,
isHEVCFlavor ? 2 : 1,
timeOffset + compositionOffset / timescale,
seiSamples
);
}
sampleOffset += naluSize;
naluTotalSize += naluSize + 4;
}
}
timeOffset += sampleDuration / timescale;
}
});
}
});
});
});
return seiSamples;
}
function isHEVC(codec: string) {
if (!codec) {
return false;
}
const delimit = codec.indexOf('.');
const baseCodec = delimit < 0 ? codec : codec.substring(0, delimit);
return (
baseCodec === 'hvc1' ||
baseCodec === 'hev1' ||
// Dolby Vision
baseCodec === 'dvh1' ||
baseCodec === 'dvhe'
);
}
function isSEIMessage(isHEVCFlavor: boolean, naluHeader: number) {
if (isHEVCFlavor) {
const naluType = (naluHeader >> 1) & 0x3f;
return naluType === 39 || naluType === 40;
} else {
const naluType = naluHeader & 0x1f;
return naluType === 6;
}
}
export function parseSEIMessageFromNALu(
unescapedData: Uint8Array,
headerSize: number,
pts: number,
samples: UserdataSample[]
) {
const data = discardEPB(unescapedData);
let seiPtr = 0;
// skip nal header
seiPtr += headerSize;
let payloadType = 0;
let payloadSize = 0;
let endOfCaptions = false;
let b = 0;
while (seiPtr < data.length) {
payloadType = 0;
do {
if (seiPtr >= data.length) {
break;
}
b = data[seiPtr++];
payloadType += b;
} while (b === 0xff);
// Parse payload size.
payloadSize = 0;
do {
if (seiPtr >= data.length) {
break;
}
b = data[seiPtr++];
payloadSize += b;
} while (b === 0xff);
const leftOver = data.length - seiPtr;
if (!endOfCaptions && payloadType === 4 && seiPtr < data.length) {
endOfCaptions = true;
const countryCode = data[seiPtr++];
if (countryCode === 181) {
const providerCode = readUint16(data, seiPtr);
seiPtr += 2;
if (providerCode === 49) {
const userStructure = readUint32(data, seiPtr);
seiPtr += 4;
if (userStructure === 0x47413934) {
const userDataType = data[seiPtr++];
// Raw CEA-608 bytes wrapped in CEA-708 packet
if (userDataType === 3) {
const firstByte = data[seiPtr++];
const totalCCs = 0x1f & firstByte;
const enabled = 0x40 & firstByte;
const totalBytes = enabled ? 2 + totalCCs * 3 : 0;
const byteArray = new Uint8Array(totalBytes);
if (enabled) {
byteArray[0] = firstByte;
for (let i = 1; i < totalBytes; i++) {
byteArray[i] = data[seiPtr++];
}
}
samples.push({
type: userDataType,
payloadType,
pts,
bytes: byteArray,
});
}
}
}
}
} else if (payloadType === 5 && payloadSize < leftOver) {
endOfCaptions = true;
if (payloadSize > 16) {
const uuidStrArray: Array<string> = [];
for (let i = 0; i < 16; i++) {
const b = data[seiPtr++].toString(16);
uuidStrArray.push(b.length == 1 ? '0' + b : b);
if (i === 3 || i === 5 || i === 7 || i === 9) {
uuidStrArray.push('-');
}
}
const length = payloadSize - 16;
const userDataBytes = new Uint8Array(length);
for (let i = 0; i < length; i++) {
userDataBytes[i] = data[seiPtr++];
}
samples.push({
payloadType,
pts,
uuid: uuidStrArray.join(''),
userData: utf8ArrayToStr(userDataBytes),
userDataBytes,
});
}
} else if (payloadSize < leftOver) {
seiPtr += payloadSize;
} else if (payloadSize > leftOver) {
break;
}
}
}
/**
* remove Emulation Prevention bytes from a RBSP
*/
export function discardEPB(data: Uint8Array): Uint8Array {
const length = data.byteLength;
const EPBPositions = [] as Array<number>;
let i = 1;
// Find all `Emulation Prevention Bytes`
while (i < length - 2) {
if (data[i] === 0 && data[i + 1] === 0 && data[i + 2] === 0x03) {
EPBPositions.push(i + 2);
i += 2;
} else {
i++;
}
}
// If no Emulation Prevention Bytes were found just return the original
// array
if (EPBPositions.length === 0) {
return data;
}
// Create a new array to hold the NAL unit data
const newLength = length - EPBPositions.length;
const newData = new Uint8Array(newLength);
let sourceIndex = 0;
for (i = 0; i < newLength; sourceIndex++, i++) {
if (sourceIndex === EPBPositions[0]) {
// Skip this byte
sourceIndex++;
// Remove this position index
EPBPositions.shift();
}
newData[i] = data[sourceIndex];
}
return newData;
}
export function parseEmsg(data: Uint8Array): IEmsgParsingData {
const version = data[0];
let schemeIdUri: string = '';
let value: string = '';
let timeScale: number = 0;
let presentationTimeDelta: number = 0;
let presentationTime: number = 0;
let eventDuration: number = 0;
let id: number = 0;
let offset: number = 0;
if (version === 0) {
while (bin2str(data.subarray(offset, offset + 1)) !== '\0') {
schemeIdUri += bin2str(data.subarray(offset, offset + 1));
offset += 1;
}
schemeIdUri += bin2str(data.subarray(offset, offset + 1));
offset += 1;
while (bin2str(data.subarray(offset, offset + 1)) !== '\0') {
value += bin2str(data.subarray(offset, offset + 1));
offset += 1;
}
value += bin2str(data.subarray(offset, offset + 1));
offset += 1;
timeScale = readUint32(data, 12);
presentationTimeDelta = readUint32(data, 16);
eventDuration = readUint32(data, 20);
id = readUint32(data, 24);
offset = 28;
} else if (version === 1) {
offset += 4;
timeScale = readUint32(data, offset);
offset += 4;
const leftPresentationTime = readUint32(data, offset);
offset += 4;
const rightPresentationTime = readUint32(data, offset);
offset += 4;
presentationTime = 2 ** 32 * leftPresentationTime + rightPresentationTime;
if (!Number.isSafeInteger(presentationTime)) {
presentationTime = Number.MAX_SAFE_INTEGER;
// eslint-disable-next-line no-console
console.warn(
'Presentation time exceeds safe integer limit and wrapped to max safe integer in parsing emsg box'
);
}
eventDuration = readUint32(data, offset);