forked from AOMediaCodec/libavif
-
Notifications
You must be signed in to change notification settings - Fork 0
/
Copy pathwrite.c
1497 lines (1291 loc) · 70.4 KB
/
write.c
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
// Copyright 2019 Joe Drago. All rights reserved.
// SPDX-License-Identifier: BSD-2-Clause
#include "avif/internal.h"
#include <assert.h>
#include <string.h>
#include <time.h>
#define MAX_ASSOCIATIONS 16
struct ipmaArray
{
uint8_t associations[MAX_ASSOCIATIONS];
avifBool essential[MAX_ASSOCIATIONS];
uint8_t count;
};
static void ipmaPush(struct ipmaArray * ipma, uint8_t assoc, avifBool essential)
{
ipma->associations[ipma->count] = assoc;
ipma->essential[ipma->count] = essential;
++ipma->count;
}
// Used to store offsets in meta boxes which need to point at mdat offsets that
// aren't known yet. When an item's mdat payload is written, all registered fixups
// will have this now-known offset "fixed up".
typedef struct avifOffsetFixup
{
size_t offset;
} avifOffsetFixup;
AVIF_ARRAY_DECLARE(avifOffsetFixupArray, avifOffsetFixup, fixup);
static const char alphaURN[] = URN_ALPHA0;
static const size_t alphaURNSize = sizeof(alphaURN);
static const char xmpContentType[] = CONTENT_TYPE_XMP;
static const size_t xmpContentTypeSize = sizeof(xmpContentType);
static avifBool avifImageIsOpaque(const avifImage * image);
static void writeConfigBox(avifRWStream * s, avifCodecConfigurationBox * cfg);
// ---------------------------------------------------------------------------
// avifCodecEncodeOutput
avifCodecEncodeOutput * avifCodecEncodeOutputCreate(void)
{
avifCodecEncodeOutput * encodeOutput = (avifCodecEncodeOutput *)avifAlloc(sizeof(avifCodecEncodeOutput));
memset(encodeOutput, 0, sizeof(avifCodecEncodeOutput));
avifArrayCreate(&encodeOutput->samples, sizeof(avifEncodeSample), 1);
return encodeOutput;
}
void avifCodecEncodeOutputAddSample(avifCodecEncodeOutput * encodeOutput, const uint8_t * data, size_t len, avifBool sync)
{
avifEncodeSample * sample = (avifEncodeSample *)avifArrayPushPtr(&encodeOutput->samples);
avifRWDataSet(&sample->data, data, len);
sample->sync = sync;
}
void avifCodecEncodeOutputDestroy(avifCodecEncodeOutput * encodeOutput)
{
for (uint32_t sampleIndex = 0; sampleIndex < encodeOutput->samples.count; ++sampleIndex) {
avifRWDataFree(&encodeOutput->samples.sample[sampleIndex].data);
}
avifArrayDestroy(&encodeOutput->samples);
avifFree(encodeOutput);
}
// ---------------------------------------------------------------------------
// avifEncoderItem
// one "item" worth for encoder
typedef struct avifEncoderItem
{
uint16_t id;
uint8_t type[4];
avifCodec * codec; // only present on type==av01
avifCodecEncodeOutput * encodeOutput; // AV1 sample data
avifRWData metadataPayload; // Exif/XMP data
avifCodecConfigurationBox av1C; // Harvested in avifEncoderFinish(), if encodeOutput has samples
uint32_t cellIndex; // Which row-major cell index corresponds to this item. ignored on non-av01 types
avifBool alpha;
const char * infeName;
size_t infeNameSize;
const char * infeContentType;
size_t infeContentTypeSize;
avifOffsetFixupArray mdatFixups;
uint16_t irefToID; // if non-zero, make an iref from this id -> irefToID
const char * irefType;
uint32_t gridCols; // if non-zero (legal range [1-256]), this is a grid item
uint32_t gridRows; // if non-zero (legal range [1-256]), this is a grid item
uint16_t dimgFromID; // if non-zero, make an iref from dimgFromID -> this id
struct ipmaArray ipma;
} avifEncoderItem;
AVIF_ARRAY_DECLARE(avifEncoderItemArray, avifEncoderItem, item);
// ---------------------------------------------------------------------------
// avifEncoderFrame
typedef struct avifEncoderFrame
{
uint64_t durationInTimescales;
} avifEncoderFrame;
AVIF_ARRAY_DECLARE(avifEncoderFrameArray, avifEncoderFrame, frame);
// ---------------------------------------------------------------------------
// avifEncoderData
typedef struct avifEncoderData
{
avifEncoderItemArray items;
avifEncoderFrameArray frames;
avifImage * imageMetadata;
uint16_t lastItemID;
uint16_t primaryItemID;
avifBool singleImage; // if true, the AVIF_ADD_IMAGE_FLAG_SINGLE flag was set on the first call to avifEncoderAddImage()
avifBool alphaPresent;
} avifEncoderData;
static avifEncoderData * avifEncoderDataCreate()
{
avifEncoderData * data = (avifEncoderData *)avifAlloc(sizeof(avifEncoderData));
memset(data, 0, sizeof(avifEncoderData));
data->imageMetadata = avifImageCreateEmpty();
avifArrayCreate(&data->items, sizeof(avifEncoderItem), 8);
avifArrayCreate(&data->frames, sizeof(avifEncoderFrame), 1);
return data;
}
static avifEncoderItem * avifEncoderDataCreateItem(avifEncoderData * data, const char * type, const char * infeName, size_t infeNameSize, uint32_t cellIndex)
{
avifEncoderItem * item = (avifEncoderItem *)avifArrayPushPtr(&data->items);
++data->lastItemID;
item->id = data->lastItemID;
memcpy(item->type, type, sizeof(item->type));
item->infeName = infeName;
item->infeNameSize = infeNameSize;
item->encodeOutput = avifCodecEncodeOutputCreate();
item->cellIndex = cellIndex;
avifArrayCreate(&item->mdatFixups, sizeof(avifOffsetFixup), 4);
return item;
}
static avifEncoderItem * avifEncoderDataFindItemByID(avifEncoderData * data, uint16_t id)
{
for (uint32_t itemIndex = 0; itemIndex < data->items.count; ++itemIndex) {
avifEncoderItem * item = &data->items.item[itemIndex];
if (item->id == id) {
return item;
}
}
return NULL;
}
static void avifEncoderDataDestroy(avifEncoderData * data)
{
for (uint32_t i = 0; i < data->items.count; ++i) {
avifEncoderItem * item = &data->items.item[i];
if (item->codec) {
avifCodecDestroy(item->codec);
}
avifCodecEncodeOutputDestroy(item->encodeOutput);
avifRWDataFree(&item->metadataPayload);
avifArrayDestroy(&item->mdatFixups);
}
avifImageDestroy(data->imageMetadata);
avifArrayDestroy(&data->items);
avifArrayDestroy(&data->frames);
avifFree(data);
}
static void avifEncoderItemAddMdatFixup(avifEncoderItem * item, const avifRWStream * s)
{
avifOffsetFixup * fixup = (avifOffsetFixup *)avifArrayPushPtr(&item->mdatFixups);
fixup->offset = avifRWStreamOffset(s);
}
// ---------------------------------------------------------------------------
// avifItemPropertyDedup - Provides ipco deduplication
typedef struct avifItemProperty
{
uint8_t index;
size_t offset;
size_t size;
} avifItemProperty;
AVIF_ARRAY_DECLARE(avifItemPropertyArray, avifItemProperty, property);
typedef struct avifItemPropertyDedup
{
avifItemPropertyArray properties;
avifRWStream s; // Temporary stream for each new property, checked against already-written boxes for deduplications
avifRWData buffer; // Temporary storage for 's'
uint8_t nextIndex; // 1-indexed, incremented every time another unique property is finished
} avifItemPropertyDedup;
static avifItemPropertyDedup * avifItemPropertyDedupCreate(void)
{
avifItemPropertyDedup * dedup = (avifItemPropertyDedup *)avifAlloc(sizeof(avifItemPropertyDedup));
memset(dedup, 0, sizeof(avifItemPropertyDedup));
avifArrayCreate(&dedup->properties, sizeof(avifItemProperty), 8);
avifRWDataRealloc(&dedup->buffer, 2048); // This will resize automatically (if necessary)
return dedup;
}
static void avifItemPropertyDedupDestroy(avifItemPropertyDedup * dedup)
{
avifArrayDestroy(&dedup->properties);
avifRWDataFree(&dedup->buffer);
avifFree(dedup);
}
// Resets the dedup's temporary write stream in preparation for a single item property's worth of writing
static void avifItemPropertyDedupStart(avifItemPropertyDedup * dedup)
{
avifRWStreamStart(&dedup->s, &dedup->buffer);
}
// This compares the newly written item property (in the dedup's temporary storage buffer) to
// already-written properties (whose offsets/sizes in outputStream are recorded in the dedup). If a
// match is found, the previous item's index is used. If this new property is unique, it is
// assigned the next available property index, written to the output stream, and its offset/size in
// the output stream is recorded in the dedup for future comparisons.
//
// This function always returns a valid 1-indexed property index for usage in a property association
// (ipma) box later. If the most recent property was a duplicate of a previous property, the return
// value will be the index of the original property, otherwise it will be the index of the newly
// created property.
static uint8_t avifItemPropertyDedupFinish(avifItemPropertyDedup * dedup, avifRWStream * outputStream)
{
const size_t newPropertySize = avifRWStreamOffset(&dedup->s);
for (size_t i = 0; i < dedup->properties.count; ++i) {
avifItemProperty * property = &dedup->properties.property[i];
if ((property->size == newPropertySize) &&
!memcmp(&outputStream->raw->data[property->offset], dedup->buffer.data, newPropertySize)) {
// We've already written this exact property, reuse it
return property->index;
}
}
// Write a new property, and remember its location in the output stream for future deduplication
avifItemProperty * property = (avifItemProperty *)avifArrayPushPtr(&dedup->properties);
property->index = ++dedup->nextIndex; // preincrement so the first new index is 1 (as ipma is 1-indexed)
property->size = newPropertySize;
property->offset = avifRWStreamOffset(outputStream);
avifRWStreamWrite(outputStream, dedup->buffer.data, newPropertySize);
return property->index;
}
// ---------------------------------------------------------------------------
avifEncoder * avifEncoderCreate(void)
{
avifEncoder * encoder = (avifEncoder *)avifAlloc(sizeof(avifEncoder));
memset(encoder, 0, sizeof(avifEncoder));
encoder->maxThreads = 1;
encoder->minQuantizer = AVIF_QUANTIZER_LOSSLESS;
encoder->maxQuantizer = AVIF_QUANTIZER_LOSSLESS;
encoder->minQuantizerAlpha = AVIF_QUANTIZER_LOSSLESS;
encoder->maxQuantizerAlpha = AVIF_QUANTIZER_LOSSLESS;
encoder->tileRowsLog2 = 0;
encoder->tileColsLog2 = 0;
encoder->speed = AVIF_SPEED_DEFAULT;
encoder->keyframeInterval = 0;
encoder->timescale = 1;
encoder->data = avifEncoderDataCreate();
encoder->csOptions = avifCodecSpecificOptionsCreate();
return encoder;
}
void avifEncoderDestroy(avifEncoder * encoder)
{
avifCodecSpecificOptionsDestroy(encoder->csOptions);
avifEncoderDataDestroy(encoder->data);
avifFree(encoder);
}
void avifEncoderSetCodecSpecificOption(avifEncoder * encoder, const char * key, const char * value)
{
avifCodecSpecificOptionsSet(encoder->csOptions, key, value);
}
// This function is used in two codepaths:
// * writing color *item* properties
// * writing color *track* properties
//
// Item properties must have property associations with them and can be deduplicated (by reusing
// these associations), so this function leverages the ipma and dedup arguments to do this.
//
// Track properties, however, are implicitly associated by the track in which they are contained, so
// there is no need to build a property association box (ipma), and no way to deduplicate/reuse a
// property. In this case, the ipma and dedup properties should/will be set to NULL, and this
// function will avoid using them.
static void avifEncoderWriteColorProperties(avifRWStream * outputStream,
const avifImage * imageMetadata,
struct ipmaArray * ipma,
avifItemPropertyDedup * dedup)
{
avifRWStream * s = outputStream;
if (dedup) {
assert(ipma);
// Use the dedup's temporary stream for box writes
s = &dedup->s;
}
if (imageMetadata->icc.size > 0) {
if (dedup) {
avifItemPropertyDedupStart(dedup);
}
avifBoxMarker colr = avifRWStreamWriteBox(s, "colr", AVIF_BOX_SIZE_TBD);
avifRWStreamWriteChars(s, "prof", 4); // unsigned int(32) colour_type;
avifRWStreamWrite(s, imageMetadata->icc.data, imageMetadata->icc.size);
avifRWStreamFinishBox(s, colr);
if (dedup) {
ipmaPush(ipma, avifItemPropertyDedupFinish(dedup, outputStream), AVIF_FALSE);
}
}
// HEIF 6.5.5.1, from Amendment 3 allows multiple colr boxes: "at most one for a given value of colour type"
// Therefore, *always* writing an nclx box, even if an a prof box was already written above.
if (dedup) {
avifItemPropertyDedupStart(dedup);
}
avifBoxMarker colr = avifRWStreamWriteBox(s, "colr", AVIF_BOX_SIZE_TBD);
avifRWStreamWriteChars(s, "nclx", 4); // unsigned int(32) colour_type;
avifRWStreamWriteU16(s, imageMetadata->colorPrimaries); // unsigned int(16) colour_primaries;
avifRWStreamWriteU16(s, imageMetadata->transferCharacteristics); // unsigned int(16) transfer_characteristics;
avifRWStreamWriteU16(s, imageMetadata->matrixCoefficients); // unsigned int(16) matrix_coefficients;
avifRWStreamWriteU8(s, (imageMetadata->yuvRange == AVIF_RANGE_FULL) ? 0x80 : 0); // unsigned int(1) full_range_flag;
// unsigned int(7) reserved = 0;
avifRWStreamFinishBox(s, colr);
if (dedup) {
ipmaPush(ipma, avifItemPropertyDedupFinish(dedup, outputStream), AVIF_FALSE);
}
// Write (Optional) Transformations
if (imageMetadata->transformFlags & AVIF_TRANSFORM_PASP) {
if (dedup) {
avifItemPropertyDedupStart(dedup);
}
avifBoxMarker pasp = avifRWStreamWriteBox(s, "pasp", AVIF_BOX_SIZE_TBD);
avifRWStreamWriteU32(s, imageMetadata->pasp.hSpacing); // unsigned int(32) hSpacing;
avifRWStreamWriteU32(s, imageMetadata->pasp.vSpacing); // unsigned int(32) vSpacing;
avifRWStreamFinishBox(s, pasp);
if (dedup) {
ipmaPush(ipma, avifItemPropertyDedupFinish(dedup, outputStream), AVIF_FALSE);
}
}
if (imageMetadata->transformFlags & AVIF_TRANSFORM_CLAP) {
if (dedup) {
avifItemPropertyDedupStart(dedup);
}
avifBoxMarker clap = avifRWStreamWriteBox(s, "clap", AVIF_BOX_SIZE_TBD);
avifRWStreamWriteU32(s, imageMetadata->clap.widthN); // unsigned int(32) cleanApertureWidthN;
avifRWStreamWriteU32(s, imageMetadata->clap.widthD); // unsigned int(32) cleanApertureWidthD;
avifRWStreamWriteU32(s, imageMetadata->clap.heightN); // unsigned int(32) cleanApertureHeightN;
avifRWStreamWriteU32(s, imageMetadata->clap.heightD); // unsigned int(32) cleanApertureHeightD;
avifRWStreamWriteU32(s, imageMetadata->clap.horizOffN); // unsigned int(32) horizOffN;
avifRWStreamWriteU32(s, imageMetadata->clap.horizOffD); // unsigned int(32) horizOffD;
avifRWStreamWriteU32(s, imageMetadata->clap.vertOffN); // unsigned int(32) vertOffN;
avifRWStreamWriteU32(s, imageMetadata->clap.vertOffD); // unsigned int(32) vertOffD;
avifRWStreamFinishBox(s, clap);
if (dedup) {
ipmaPush(ipma, avifItemPropertyDedupFinish(dedup, outputStream), AVIF_TRUE);
}
}
if (imageMetadata->transformFlags & AVIF_TRANSFORM_IROT) {
if (dedup) {
avifItemPropertyDedupStart(dedup);
}
avifBoxMarker irot = avifRWStreamWriteBox(s, "irot", AVIF_BOX_SIZE_TBD);
uint8_t angle = imageMetadata->irot.angle & 0x3;
avifRWStreamWrite(s, &angle, 1); // unsigned int (6) reserved = 0; unsigned int (2) angle;
avifRWStreamFinishBox(s, irot);
if (dedup) {
ipmaPush(ipma, avifItemPropertyDedupFinish(dedup, outputStream), AVIF_TRUE);
}
}
if (imageMetadata->transformFlags & AVIF_TRANSFORM_IMIR) {
if (dedup) {
avifItemPropertyDedupStart(dedup);
}
avifBoxMarker imir = avifRWStreamWriteBox(s, "imir", AVIF_BOX_SIZE_TBD);
uint8_t mode = imageMetadata->imir.mode & 0x1;
avifRWStreamWrite(s, &mode, 1); // unsigned int (7) reserved = 0; unsigned int (1) mode;
avifRWStreamFinishBox(s, imir);
if (dedup) {
ipmaPush(ipma, avifItemPropertyDedupFinish(dedup, outputStream), AVIF_TRUE);
}
}
}
// Write unassociated metadata items (EXIF, XMP) to a small meta box inside of a trak box.
// These items are implicitly associated with the track they are contained within.
static void avifEncoderWriteTrackMetaBox(avifEncoder * encoder, avifRWStream * s)
{
// Count how many non-av01 items (such as EXIF/XMP) are being written
uint32_t metadataItemCount = 0;
for (uint32_t itemIndex = 0; itemIndex < encoder->data->items.count; ++itemIndex) {
avifEncoderItem * item = &encoder->data->items.item[itemIndex];
if (memcmp(item->type, "av01", 4) != 0) {
++metadataItemCount;
}
}
if (metadataItemCount == 0) {
// Don't even bother writing the trak meta box
return;
}
avifBoxMarker meta = avifRWStreamWriteFullBox(s, "meta", AVIF_BOX_SIZE_TBD, 0, 0);
avifBoxMarker hdlr = avifRWStreamWriteFullBox(s, "hdlr", AVIF_BOX_SIZE_TBD, 0, 0);
avifRWStreamWriteU32(s, 0); // unsigned int(32) pre_defined = 0;
avifRWStreamWriteChars(s, "pict", 4); // unsigned int(32) handler_type;
avifRWStreamWriteZeros(s, 12); // const unsigned int(32)[3] reserved = 0;
avifRWStreamWriteChars(s, "libavif", 8); // string name; (writing null terminator)
avifRWStreamFinishBox(s, hdlr);
avifBoxMarker iloc = avifRWStreamWriteFullBox(s, "iloc", AVIF_BOX_SIZE_TBD, 0, 0);
uint8_t offsetSizeAndLengthSize = (4 << 4) + (4 << 0); // unsigned int(4) offset_size;
// unsigned int(4) length_size;
avifRWStreamWrite(s, &offsetSizeAndLengthSize, 1); //
avifRWStreamWriteZeros(s, 1); // unsigned int(4) base_offset_size;
// unsigned int(4) reserved;
avifRWStreamWriteU16(s, (uint16_t)metadataItemCount); // unsigned int(16) item_count;
for (uint32_t trakItemIndex = 0; trakItemIndex < encoder->data->items.count; ++trakItemIndex) {
avifEncoderItem * item = &encoder->data->items.item[trakItemIndex];
if (memcmp(item->type, "av01", 4) == 0) {
// Skip over all non-metadata items
continue;
}
avifRWStreamWriteU16(s, item->id); // unsigned int(16) item_ID;
avifRWStreamWriteU16(s, 0); // unsigned int(16) data_reference_index;
avifRWStreamWriteU16(s, 1); // unsigned int(16) extent_count;
avifEncoderItemAddMdatFixup(item, s); //
avifRWStreamWriteU32(s, 0 /* set later */); // unsigned int(offset_size*8) extent_offset;
avifRWStreamWriteU32(s, (uint32_t)item->metadataPayload.size); // unsigned int(length_size*8) extent_length;
}
avifRWStreamFinishBox(s, iloc);
avifBoxMarker iinf = avifRWStreamWriteFullBox(s, "iinf", AVIF_BOX_SIZE_TBD, 0, 0);
avifRWStreamWriteU16(s, (uint16_t)metadataItemCount); // unsigned int(16) entry_count;
for (uint32_t trakItemIndex = 0; trakItemIndex < encoder->data->items.count; ++trakItemIndex) {
avifEncoderItem * item = &encoder->data->items.item[trakItemIndex];
if (memcmp(item->type, "av01", 4) == 0) {
continue;
}
avifBoxMarker infe = avifRWStreamWriteFullBox(s, "infe", AVIF_BOX_SIZE_TBD, 2, 0);
avifRWStreamWriteU16(s, item->id); // unsigned int(16) item_ID;
avifRWStreamWriteU16(s, 0); // unsigned int(16) item_protection_index;
avifRWStreamWrite(s, item->type, 4); // unsigned int(32) item_type;
avifRWStreamWriteChars(s, item->infeName, item->infeNameSize); // string item_name; (writing null terminator)
if (item->infeContentType && item->infeContentTypeSize) { // string content_type; (writing null terminator)
avifRWStreamWriteChars(s, item->infeContentType, item->infeContentTypeSize);
}
avifRWStreamFinishBox(s, infe);
}
avifRWStreamFinishBox(s, iinf);
avifRWStreamFinishBox(s, meta);
}
static void avifWriteGridPayload(avifRWData * data, uint32_t gridCols, uint32_t gridRows, const avifImage * firstCell)
{
// ISO/IEC 23008-12 6.6.2.3.2
// aligned(8) class ImageGrid {
// unsigned int(8) version = 0;
// unsigned int(8) flags;
// FieldLength = ((flags & 1) + 1) * 16;
// unsigned int(8) rows_minus_one;
// unsigned int(8) columns_minus_one;
// unsigned int(FieldLength) output_width;
// unsigned int(FieldLength) output_height;
// }
uint32_t gridWidth = firstCell->width * gridCols;
uint32_t gridHeight = firstCell->height * gridRows;
uint8_t gridFlags = ((gridWidth > 65535) || (gridHeight > 65535)) ? 1 : 0;
avifRWStream s;
avifRWStreamStart(&s, data);
avifRWStreamWriteU8(&s, 0); // unsigned int(8) version = 0;
avifRWStreamWriteU8(&s, gridFlags); // unsigned int(8) flags;
avifRWStreamWriteU8(&s, (uint8_t)(gridRows - 1)); // unsigned int(8) rows_minus_one;
avifRWStreamWriteU8(&s, (uint8_t)(gridCols - 1)); // unsigned int(8) columns_minus_one;
if (gridFlags & 1) {
avifRWStreamWriteU32(&s, gridWidth); // unsigned int(FieldLength) output_width;
avifRWStreamWriteU32(&s, gridHeight); // unsigned int(FieldLength) output_height;
} else {
uint16_t tmpWidth = (uint16_t)gridWidth;
uint16_t tmpHeight = (uint16_t)gridHeight;
avifRWStreamWriteU16(&s, tmpWidth); // unsigned int(FieldLength) output_width;
avifRWStreamWriteU16(&s, tmpHeight); // unsigned int(FieldLength) output_height;
}
avifRWStreamFinishWrite(&s);
}
static avifResult avifEncoderAddImageInternal(avifEncoder * encoder,
uint32_t gridCols,
uint32_t gridRows,
const avifImage * const * cellImages,
uint64_t durationInTimescales,
avifAddImageFlags addImageFlags)
{
// -----------------------------------------------------------------------
// Verify encoding is possible
if (!avifCodecName(encoder->codecChoice, AVIF_CODEC_FLAG_CAN_ENCODE)) {
return AVIF_RESULT_NO_CODEC_AVAILABLE;
}
// -----------------------------------------------------------------------
// Validate images
const uint32_t cellCount = gridCols * gridRows;
if (cellCount == 0) {
return AVIF_RESULT_INVALID_ARGUMENT;
}
const avifImage * firstCell = cellImages[0];
if ((firstCell->depth != 8) && (firstCell->depth != 10) && (firstCell->depth != 12)) {
return AVIF_RESULT_UNSUPPORTED_DEPTH;
}
if (!firstCell->width || !firstCell->height) {
return AVIF_RESULT_NO_CONTENT;
}
if ((cellCount > 1) && ((firstCell->width < 64) || (firstCell->height < 64))) {
return AVIF_RESULT_INVALID_IMAGE_GRID;
}
for (uint32_t cellIndex = 0; cellIndex < cellCount; ++cellIndex) {
const avifImage * cellImage = cellImages[cellIndex];
if ((cellImage->depth != firstCell->depth) || (cellImage->width != firstCell->width) ||
(cellImage->height != firstCell->height) || (!!cellImage->alphaPlane != !!firstCell->alphaPlane) ||
(cellImage->alphaPremultiplied != firstCell->alphaPremultiplied)) {
return AVIF_RESULT_INVALID_IMAGE_GRID;
}
if (!cellImage->yuvPlanes[AVIF_CHAN_Y]) {
return AVIF_RESULT_NO_CONTENT;
}
if (cellImage->yuvFormat == AVIF_PIXEL_FORMAT_NONE) {
return AVIF_RESULT_NO_YUV_FORMAT_SELECTED;
}
}
// -----------------------------------------------------------------------
// Validate flags
if (encoder->data->singleImage) {
// The previous call to avifEncoderAddImage() set AVIF_ADD_IMAGE_FLAG_SINGLE.
// avifEncoderAddImage() cannot be called again for this encode.
return AVIF_RESULT_ENCODE_COLOR_FAILED;
}
if (addImageFlags & AVIF_ADD_IMAGE_FLAG_SINGLE) {
encoder->data->singleImage = AVIF_TRUE;
if (encoder->data->items.count > 0) {
// AVIF_ADD_IMAGE_FLAG_SINGLE may only be set on the first and only image.
return AVIF_RESULT_INVALID_ARGUMENT;
}
}
// -----------------------------------------------------------------------
if (durationInTimescales == 0) {
durationInTimescales = 1;
}
if (encoder->data->items.count == 0) {
// Make a copy of the first image's metadata (sans pixels) for future writing/validation
avifImageCopy(encoder->data->imageMetadata, firstCell, 0);
// Prepare all AV1 items
uint16_t gridColorID = 0;
if (cellCount > 1) {
avifEncoderItem * gridColorItem = avifEncoderDataCreateItem(encoder->data, "grid", "Color", 6, 0);
avifWriteGridPayload(&gridColorItem->metadataPayload, gridCols, gridRows, firstCell);
gridColorItem->gridCols = gridCols;
gridColorItem->gridRows = gridRows;
gridColorID = gridColorItem->id;
encoder->data->primaryItemID = gridColorID;
}
for (uint32_t cellIndex = 0; cellIndex < cellCount; ++cellIndex) {
avifEncoderItem * item = avifEncoderDataCreateItem(encoder->data, "av01", "Color", 6, cellIndex);
item->codec = avifCodecCreate(encoder->codecChoice, AVIF_CODEC_FLAG_CAN_ENCODE);
if (!item->codec) {
// Just bail out early, we're not surviving this function without an encoder compiled in
return AVIF_RESULT_NO_CODEC_AVAILABLE;
}
item->codec->csOptions = encoder->csOptions;
item->codec->diag = &encoder->diag;
if (cellCount > 1) {
item->dimgFromID = gridColorID;
} else {
encoder->data->primaryItemID = item->id;
}
}
encoder->data->alphaPresent = (firstCell->alphaPlane != NULL);
if (encoder->data->alphaPresent && (addImageFlags & AVIF_ADD_IMAGE_FLAG_SINGLE)) {
// If encoding a single image in which the alpha plane exists but is entirely opaque,
// simply skip writing an alpha AV1 payload entirely, as it'll be interpreted as opaque
// and is less bytes.
//
// However, if encoding an image sequence, the first frame's alpha plane being entirely
// opaque could be a false positive for removing the alpha AV1 payload, as it might simply
// be a fade out later in the sequence. This is why avifImageIsOpaque() is only called
// when encoding a single image.
encoder->data->alphaPresent = AVIF_FALSE;
for (uint32_t cellIndex = 0; cellIndex < cellCount; ++cellIndex) {
const avifImage * cellImage = cellImages[cellIndex];
if (!avifImageIsOpaque(cellImage)) {
encoder->data->alphaPresent = AVIF_TRUE;
break;
}
}
}
if (encoder->data->alphaPresent) {
uint16_t gridAlphaID = 0;
if (cellCount > 1) {
avifEncoderItem * gridAlphaItem = avifEncoderDataCreateItem(encoder->data, "grid", "Alpha", 6, 0);
avifWriteGridPayload(&gridAlphaItem->metadataPayload, gridCols, gridRows, firstCell);
gridAlphaItem->alpha = AVIF_TRUE;
gridAlphaItem->irefToID = encoder->data->primaryItemID;
gridAlphaItem->irefType = "auxl";
gridAlphaItem->gridCols = gridCols;
gridAlphaItem->gridRows = gridRows;
gridAlphaID = gridAlphaItem->id;
if (encoder->data->imageMetadata->alphaPremultiplied) {
avifEncoderItem * primaryItem = avifEncoderDataFindItemByID(encoder->data, encoder->data->primaryItemID);
assert(primaryItem);
primaryItem->irefType = "prem";
primaryItem->irefToID = gridAlphaID;
}
}
for (uint32_t cellIndex = 0; cellIndex < cellCount; ++cellIndex) {
avifEncoderItem * item = avifEncoderDataCreateItem(encoder->data, "av01", "Alpha", 6, cellIndex);
item->codec = avifCodecCreate(encoder->codecChoice, AVIF_CODEC_FLAG_CAN_ENCODE);
if (!item->codec) {
return AVIF_RESULT_NO_CODEC_AVAILABLE;
}
item->codec->csOptions = encoder->csOptions;
item->codec->diag = &encoder->diag;
item->alpha = AVIF_TRUE;
if (cellCount > 1) {
item->dimgFromID = gridAlphaID;
} else {
item->irefToID = encoder->data->primaryItemID;
item->irefType = "auxl";
if (encoder->data->imageMetadata->alphaPremultiplied) {
avifEncoderItem * primaryItem = avifEncoderDataFindItemByID(encoder->data, encoder->data->primaryItemID);
assert(primaryItem);
primaryItem->irefType = "prem";
primaryItem->irefToID = item->id;
}
}
}
}
// -----------------------------------------------------------------------
// Create metadata items (Exif, XMP)
if (firstCell->exif.size > 0) {
// Validate Exif payload (if any) and find TIFF header offset
uint32_t exifTiffHeaderOffset = 0;
if (firstCell->exif.size < 4) {
// Can't even fit the TIFF header, something is wrong
return AVIF_RESULT_INVALID_EXIF_PAYLOAD;
}
const uint8_t tiffHeaderBE[4] = { 'M', 'M', 0, 42 };
const uint8_t tiffHeaderLE[4] = { 'I', 'I', 42, 0 };
for (; exifTiffHeaderOffset < (firstCell->exif.size - 4); ++exifTiffHeaderOffset) {
if (!memcmp(&firstCell->exif.data[exifTiffHeaderOffset], tiffHeaderBE, sizeof(tiffHeaderBE))) {
break;
}
if (!memcmp(&firstCell->exif.data[exifTiffHeaderOffset], tiffHeaderLE, sizeof(tiffHeaderLE))) {
break;
}
}
if (exifTiffHeaderOffset >= firstCell->exif.size - 4) {
// Couldn't find the TIFF header
return AVIF_RESULT_INVALID_EXIF_PAYLOAD;
}
avifEncoderItem * exifItem = avifEncoderDataCreateItem(encoder->data, "Exif", "Exif", 5, 0);
exifItem->irefToID = encoder->data->primaryItemID;
exifItem->irefType = "cdsc";
avifRWDataRealloc(&exifItem->metadataPayload, sizeof(uint32_t) + firstCell->exif.size);
exifTiffHeaderOffset = avifHTONL(exifTiffHeaderOffset);
memcpy(exifItem->metadataPayload.data, &exifTiffHeaderOffset, sizeof(uint32_t));
memcpy(exifItem->metadataPayload.data + sizeof(uint32_t), firstCell->exif.data, firstCell->exif.size);
}
if (firstCell->xmp.size > 0) {
avifEncoderItem * xmpItem = avifEncoderDataCreateItem(encoder->data, "mime", "XMP", 4, 0);
xmpItem->irefToID = encoder->data->primaryItemID;
xmpItem->irefType = "cdsc";
xmpItem->infeContentType = xmpContentType;
xmpItem->infeContentTypeSize = xmpContentTypeSize;
avifRWDataSet(&xmpItem->metadataPayload, firstCell->xmp.data, firstCell->xmp.size);
}
} else {
// Another frame in an image sequence
if (encoder->data->alphaPresent && !firstCell->alphaPlane) {
// If the first image in the sequence had an alpha plane (even if fully opaque), all
// subsequence images must have alpha as well.
return AVIF_RESULT_ENCODE_ALPHA_FAILED;
}
}
// -----------------------------------------------------------------------
// Encode AV1 OBUs
if (encoder->keyframeInterval && ((encoder->data->frames.count % encoder->keyframeInterval) == 0)) {
addImageFlags |= AVIF_ADD_IMAGE_FLAG_FORCE_KEYFRAME;
}
for (uint32_t itemIndex = 0; itemIndex < encoder->data->items.count; ++itemIndex) {
avifEncoderItem * item = &encoder->data->items.item[itemIndex];
if (item->codec) {
const avifImage * cellImage = cellImages[item->cellIndex];
avifResult encodeResult =
item->codec->encodeImage(item->codec, encoder, cellImage, item->alpha, addImageFlags, item->encodeOutput);
if (encodeResult == AVIF_RESULT_UNKNOWN_ERROR) {
encodeResult = item->alpha ? AVIF_RESULT_ENCODE_ALPHA_FAILED : AVIF_RESULT_ENCODE_COLOR_FAILED;
}
if (encodeResult != AVIF_RESULT_OK) {
return encodeResult;
}
}
}
avifEncoderFrame * frame = (avifEncoderFrame *)avifArrayPushPtr(&encoder->data->frames);
frame->durationInTimescales = durationInTimescales;
return AVIF_RESULT_OK;
}
avifResult avifEncoderAddImage(avifEncoder * encoder, const avifImage * image, uint64_t durationInTimescales, avifAddImageFlags addImageFlags)
{
avifDiagnosticsClearError(&encoder->diag);
return avifEncoderAddImageInternal(encoder, 1, 1, &image, durationInTimescales, addImageFlags);
}
avifResult avifEncoderAddImageGrid(avifEncoder * encoder,
uint32_t gridCols,
uint32_t gridRows,
const avifImage * const * cellImages,
avifAddImageFlags addImageFlags)
{
avifDiagnosticsClearError(&encoder->diag);
if ((gridCols == 0) || (gridCols > 256) || (gridRows == 0) || (gridRows > 256)) {
return AVIF_RESULT_INVALID_IMAGE_GRID;
}
return avifEncoderAddImageInternal(encoder, gridCols, gridRows, cellImages, 1, addImageFlags | AVIF_ADD_IMAGE_FLAG_SINGLE); // only single image grids are supported
}
static size_t avifEncoderFindExistingChunk(avifRWStream * s, size_t mdatStartOffset, const uint8_t * data, size_t size)
{
const size_t mdatCurrentOffset = avifRWStreamOffset(s);
const size_t mdatSearchSize = mdatCurrentOffset - mdatStartOffset;
if (mdatSearchSize < size) {
return 0;
}
const size_t mdatEndSearchOffset = mdatCurrentOffset - size;
for (size_t searchOffset = mdatStartOffset; searchOffset <= mdatEndSearchOffset; ++searchOffset) {
if (!memcmp(data, &s->raw->data[searchOffset], size)) {
return searchOffset;
}
}
return 0;
}
avifResult avifEncoderFinish(avifEncoder * encoder, avifRWData * output)
{
avifDiagnosticsClearError(&encoder->diag);
if (encoder->data->items.count == 0) {
return AVIF_RESULT_NO_CONTENT;
}
// -----------------------------------------------------------------------
// Finish up AV1 encoding
for (uint32_t itemIndex = 0; itemIndex < encoder->data->items.count; ++itemIndex) {
avifEncoderItem * item = &encoder->data->items.item[itemIndex];
if (item->codec) {
if (!item->codec->encodeFinish(item->codec, item->encodeOutput)) {
return item->alpha ? AVIF_RESULT_ENCODE_ALPHA_FAILED : AVIF_RESULT_ENCODE_COLOR_FAILED;
}
if (item->encodeOutput->samples.count != encoder->data->frames.count) {
return item->alpha ? AVIF_RESULT_ENCODE_ALPHA_FAILED : AVIF_RESULT_ENCODE_COLOR_FAILED;
}
}
}
// -----------------------------------------------------------------------
// Harvest av1C properties from AV1 sequence headers
for (uint32_t itemIndex = 0; itemIndex < encoder->data->items.count; ++itemIndex) {
avifEncoderItem * item = &encoder->data->items.item[itemIndex];
if (item->encodeOutput->samples.count > 0) {
const avifEncodeSample * firstSample = &item->encodeOutput->samples.sample[0];
avifSequenceHeader sequenceHeader;
if (avifSequenceHeaderParse(&sequenceHeader, (const avifROData *)&firstSample->data)) {
memcpy(&item->av1C, &sequenceHeader.av1C, sizeof(avifCodecConfigurationBox));
} else {
// This must be an invalid AV1 payload
return item->alpha ? AVIF_RESULT_ENCODE_ALPHA_FAILED : AVIF_RESULT_ENCODE_COLOR_FAILED;
}
}
}
// -----------------------------------------------------------------------
// Begin write stream
const avifImage * imageMetadata = encoder->data->imageMetadata;
// The epoch for creation_time and modification_time is midnight, Jan. 1,
// 1904, in UTC time. Add the number of seconds between that epoch and the
// Unix epoch.
uint64_t now = (uint64_t)time(NULL) + 2082844800;
avifRWStream s;
avifRWStreamStart(&s, output);
// -----------------------------------------------------------------------
// Write ftyp
const char * majorBrand = "avif";
if (encoder->data->frames.count > 1) {
majorBrand = "avis";
}
avifBoxMarker ftyp = avifRWStreamWriteBox(&s, "ftyp", AVIF_BOX_SIZE_TBD);
avifRWStreamWriteChars(&s, majorBrand, 4); // unsigned int(32) major_brand;
avifRWStreamWriteU32(&s, 0); // unsigned int(32) minor_version;
avifRWStreamWriteChars(&s, "avif", 4); // unsigned int(32) compatible_brands[];
if (encoder->data->frames.count > 1) { //
avifRWStreamWriteChars(&s, "avis", 4); // ... compatible_brands[]
avifRWStreamWriteChars(&s, "msf1", 4); // ... compatible_brands[]
} //
avifRWStreamWriteChars(&s, "mif1", 4); // ... compatible_brands[]
avifRWStreamWriteChars(&s, "miaf", 4); // ... compatible_brands[]
if ((imageMetadata->depth == 8) || (imageMetadata->depth == 10)) { //
if (imageMetadata->yuvFormat == AVIF_PIXEL_FORMAT_YUV420) { //
avifRWStreamWriteChars(&s, "MA1B", 4); // ... compatible_brands[]
} else if (imageMetadata->yuvFormat == AVIF_PIXEL_FORMAT_YUV444) { //
avifRWStreamWriteChars(&s, "MA1A", 4); // ... compatible_brands[]
}
}
avifRWStreamFinishBox(&s, ftyp);
// -----------------------------------------------------------------------
// Start meta
avifBoxMarker meta = avifRWStreamWriteFullBox(&s, "meta", AVIF_BOX_SIZE_TBD, 0, 0);
// -----------------------------------------------------------------------
// Write hdlr
avifBoxMarker hdlr = avifRWStreamWriteFullBox(&s, "hdlr", AVIF_BOX_SIZE_TBD, 0, 0);
avifRWStreamWriteU32(&s, 0); // unsigned int(32) pre_defined = 0;
avifRWStreamWriteChars(&s, "pict", 4); // unsigned int(32) handler_type;
avifRWStreamWriteZeros(&s, 12); // const unsigned int(32)[3] reserved = 0;
avifRWStreamWriteChars(&s, "libavif", 8); // string name; (writing null terminator)
avifRWStreamFinishBox(&s, hdlr);
// -----------------------------------------------------------------------
// Write pitm
if (encoder->data->primaryItemID != 0) {
avifRWStreamWriteFullBox(&s, "pitm", sizeof(uint16_t), 0, 0);
avifRWStreamWriteU16(&s, encoder->data->primaryItemID); // unsigned int(16) item_ID;
}
// -----------------------------------------------------------------------
// Write iloc
avifBoxMarker iloc = avifRWStreamWriteFullBox(&s, "iloc", AVIF_BOX_SIZE_TBD, 0, 0);
uint8_t offsetSizeAndLengthSize = (4 << 4) + (4 << 0); // unsigned int(4) offset_size;
// unsigned int(4) length_size;
avifRWStreamWrite(&s, &offsetSizeAndLengthSize, 1); //
avifRWStreamWriteZeros(&s, 1); // unsigned int(4) base_offset_size;
// unsigned int(4) reserved;
avifRWStreamWriteU16(&s, (uint16_t)encoder->data->items.count); // unsigned int(16) item_count;
for (uint32_t itemIndex = 0; itemIndex < encoder->data->items.count; ++itemIndex) {
avifEncoderItem * item = &encoder->data->items.item[itemIndex];
uint32_t contentSize = (uint32_t)item->metadataPayload.size;
if (item->encodeOutput->samples.count > 0) {
// This is choosing sample 0's size as there are two cases here:
// * This is a single image, in which case this is correct
// * This is an image sequence, but this file should still be a valid single-image avif,
// so there must still be a primary item pointing at a sync sample. Since the first
// frame of the image sequence is guaranteed to be a sync sample, it is chosen here.
//
// TODO: Offer the ability for a user to specify which frame in the sequence should
// become the primary item's image, and force that frame to be a keyframe.
contentSize = (uint32_t)item->encodeOutput->samples.sample[0].data.size;
}
avifRWStreamWriteU16(&s, item->id); // unsigned int(16) item_ID;
avifRWStreamWriteU16(&s, 0); // unsigned int(16) data_reference_index;
avifRWStreamWriteU16(&s, 1); // unsigned int(16) extent_count;
avifEncoderItemAddMdatFixup(item, &s); //
avifRWStreamWriteU32(&s, 0 /* set later */); // unsigned int(offset_size*8) extent_offset;
avifRWStreamWriteU32(&s, (uint32_t)contentSize); // unsigned int(length_size*8) extent_length;
}
avifRWStreamFinishBox(&s, iloc);
// -----------------------------------------------------------------------
// Write iinf
avifBoxMarker iinf = avifRWStreamWriteFullBox(&s, "iinf", AVIF_BOX_SIZE_TBD, 0, 0);
avifRWStreamWriteU16(&s, (uint16_t)encoder->data->items.count); // unsigned int(16) entry_count;
for (uint32_t itemIndex = 0; itemIndex < encoder->data->items.count; ++itemIndex) {
avifEncoderItem * item = &encoder->data->items.item[itemIndex];
avifBoxMarker infe = avifRWStreamWriteFullBox(&s, "infe", AVIF_BOX_SIZE_TBD, 2, 0);
avifRWStreamWriteU16(&s, item->id); // unsigned int(16) item_ID;
avifRWStreamWriteU16(&s, 0); // unsigned int(16) item_protection_index;
avifRWStreamWrite(&s, item->type, 4); // unsigned int(32) item_type;
avifRWStreamWriteChars(&s, item->infeName, item->infeNameSize); // string item_name; (writing null terminator)
if (item->infeContentType && item->infeContentTypeSize) { // string content_type; (writing null terminator)
avifRWStreamWriteChars(&s, item->infeContentType, item->infeContentTypeSize);
}
avifRWStreamFinishBox(&s, infe);
}
avifRWStreamFinishBox(&s, iinf);
// -----------------------------------------------------------------------
// Write iref boxes
avifBoxMarker iref = 0;
for (uint32_t itemIndex = 0; itemIndex < encoder->data->items.count; ++itemIndex) {
avifEncoderItem * item = &encoder->data->items.item[itemIndex];
// Count how many other items refer to this item with dimgFromID
uint16_t dimgCount = 0;
for (uint32_t dimgIndex = 0; dimgIndex < encoder->data->items.count; ++dimgIndex) {
avifEncoderItem * dimgItem = &encoder->data->items.item[dimgIndex];
if (dimgItem->dimgFromID == item->id) {
++dimgCount;
}
}
if (dimgCount > 0) {
if (!iref) {
iref = avifRWStreamWriteFullBox(&s, "iref", AVIF_BOX_SIZE_TBD, 0, 0);
}
avifBoxMarker refType = avifRWStreamWriteBox(&s, "dimg", AVIF_BOX_SIZE_TBD);
avifRWStreamWriteU16(&s, item->id); // unsigned int(16) from_item_ID;
avifRWStreamWriteU16(&s, dimgCount); // unsigned int(16) reference_count;
for (uint32_t dimgIndex = 0; dimgIndex < encoder->data->items.count; ++dimgIndex) {
avifEncoderItem * dimgItem = &encoder->data->items.item[dimgIndex];
if (dimgItem->dimgFromID == item->id) {
avifRWStreamWriteU16(&s, dimgItem->id); // unsigned int(16) to_item_ID;
}
}
avifRWStreamFinishBox(&s, refType);
}
if (item->irefToID != 0) {
if (!iref) {
iref = avifRWStreamWriteFullBox(&s, "iref", AVIF_BOX_SIZE_TBD, 0, 0);
}
avifBoxMarker refType = avifRWStreamWriteBox(&s, item->irefType, AVIF_BOX_SIZE_TBD);