aboutsummaryrefslogtreecommitdiffstats
path: root/libavformat/dashenc.c
blob: b3b1ac1d912cd0601d86ab2ca58caa95a435aea2 (plain) (blame)
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
/*
 * MPEG-DASH ISO BMFF segmenter
 * Copyright (c) 2014 Martin Storsjo
 *
 * This file is part of Libav.
 *
 * Libav is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * Libav is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with Libav; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include "config.h"
#if HAVE_UNISTD_H
#include <unistd.h>
#endif

#include "libavutil/avstring.h"
#include "libavutil/intreadwrite.h"
#include "libavutil/mathematics.h"
#include "libavutil/opt.h"
#include "libavutil/time_internal.h"

#include "avc.h"
#include "avformat.h"
#include "avio_internal.h"
#include "internal.h"
#include "isom.h"
#include "os_support.h"
#include "url.h"

// See ISO/IEC 23009-1:2014 5.3.9.4.4
typedef enum {
    DASH_TMPL_ID_UNDEFINED = -1,
    DASH_TMPL_ID_ESCAPE,
    DASH_TMPL_ID_REP_ID,
    DASH_TMPL_ID_NUMBER,
    DASH_TMPL_ID_BANDWIDTH,
    DASH_TMPL_ID_TIME,
} DASHTmplId;

typedef struct Segment {
    char file[1024];
    int64_t start_pos;
    int range_length, index_length;
    int64_t time;
    int duration;
    int n;
} Segment;

typedef struct OutputStream {
    AVFormatContext *ctx;
    int ctx_inited;
    uint8_t iobuf[32768];
    URLContext *out;
    int packets_written;
    char initfile[1024];
    int64_t init_start_pos;
    int init_range_length;
    int nb_segments, segments_size, segment_index;
    Segment **segments;
    int64_t first_dts, start_dts, end_dts;
    int bit_rate;
    char bandwidth_str[64];

    char codec_str[100];
} OutputStream;

typedef struct DASHContext {
    const AVClass *class;  /* Class for private options. */
    int window_size;
    int extra_window_size;
    int min_seg_duration;
    int remove_at_exit;
    int use_template;
    int use_timeline;
    int single_file;
    OutputStream *streams;
    int has_video, has_audio;
    int last_duration;
    int total_duration;
    char availability_start_time[100];
    char dirname[1024];
    const char *single_file_name;
    const char *init_seg_name;
    const char *media_seg_name;
} DASHContext;

static int dash_write(void *opaque, uint8_t *buf, int buf_size)
{
    OutputStream *os = opaque;
    if (os->out)
        ffurl_write(os->out, buf, buf_size);
    return buf_size;
}

// RFC 6381
static void set_codec_str(AVFormatContext *s, AVCodecContext *codec,
                          char *str, int size)
{
    const AVCodecTag *tags[2] = { NULL, NULL };
    uint32_t tag;
    if (codec->codec_type == AVMEDIA_TYPE_VIDEO)
        tags[0] = ff_codec_movvideo_tags;
    else if (codec->codec_type == AVMEDIA_TYPE_AUDIO)
        tags[0] = ff_codec_movaudio_tags;
    else
        return;

    tag = av_codec_get_tag(tags, codec->codec_id);
    if (!tag)
        return;
    if (size < 5)
        return;

    AV_WL32(str, tag);
    str[4] = '\0';
    if (!strcmp(str, "mp4a") || !strcmp(str, "mp4v")) {
        uint32_t oti;
        tags[0] = ff_mp4_obj_type;
        oti = av_codec_get_tag(tags, codec->codec_id);
        if (oti)
            av_strlcatf(str, size, ".%02x", oti);
        else
            return;

        if (tag == MKTAG('m', 'p', '4', 'a')) {
            if (codec->extradata_size >= 2) {
                int aot = codec->extradata[0] >> 3;
                if (aot == 31)
                    aot = ((AV_RB16(codec->extradata) >> 5) & 0x3f) + 32;
                av_strlcatf(str, size, ".%d", aot);
            }
        } else if (tag == MKTAG('m', 'p', '4', 'v')) {
            // Unimplemented, should output ProfileLevelIndication as a decimal number
            av_log(s, AV_LOG_WARNING, "Incomplete RFC 6381 codec string for mp4v\n");
        }
    } else if (!strcmp(str, "avc1")) {
        uint8_t *tmpbuf = NULL;
        uint8_t *extradata = codec->extradata;
        int extradata_size = codec->extradata_size;
        if (!extradata_size)
            return;
        if (extradata[0] != 1) {
            AVIOContext *pb;
            if (avio_open_dyn_buf(&pb) < 0)
                return;
            if (ff_isom_write_avcc(pb, extradata, extradata_size) < 0) {
                avio_close_dyn_buf(pb, &tmpbuf);
                av_free(tmpbuf);
                return;
            }
            extradata_size = avio_close_dyn_buf(pb, &extradata);
            tmpbuf = extradata;
        }

        if (extradata_size >= 4)
            av_strlcatf(str, size, ".%02x%02x%02x",
                        extradata[1], extradata[2], extradata[3]);
        av_free(tmpbuf);
    }
}

static void dash_free(AVFormatContext *s)
{
    DASHContext *c = s->priv_data;
    int i, j;
    if (!c->streams)
        return;
    for (i = 0; i < s->nb_streams; i++) {
        OutputStream *os = &c->streams[i];
        if (os->ctx && os->ctx_inited)
            av_write_trailer(os->ctx);
        if (os->ctx && os->ctx->pb)
            av_free(os->ctx->pb);
        ffurl_close(os->out);
        os->out =  NULL;
        if (os->ctx)
            avformat_free_context(os->ctx);
        for (j = 0; j < os->nb_segments; j++)
            av_free(os->segments[j]);
        av_free(os->segments);
    }
    av_freep(&c->streams);
}

static void output_segment_list(OutputStream *os, AVIOContext *out, DASHContext *c)
{
    int i, start_index = 0, start_number = 1;
    if (c->window_size) {
        start_index  = FFMAX(os->nb_segments   - c->window_size, 0);
        start_number = FFMAX(os->segment_index - c->window_size, 1);
    }

    if (c->use_template) {
        int timescale = c->use_timeline ? os->ctx->streams[0]->time_base.den : AV_TIME_BASE;
        avio_printf(out, "\t\t\t\t<SegmentTemplate timescale=\"%d\" ", timescale);
        if (!c->use_timeline)
            avio_printf(out, "duration=\"%d\" ", c->last_duration);
        avio_printf(out, "initialization=\"%s\" media=\"%s\" startNumber=\"%d\">\n", c->init_seg_name, c->media_seg_name, c->use_timeline ? start_number : 1);
        if (c->use_timeline) {
            avio_printf(out, "\t\t\t\t\t<SegmentTimeline>\n");
            for (i = start_index; i < os->nb_segments; ) {
                Segment *seg = os->segments[i];
                int repeat = 0;
                avio_printf(out, "\t\t\t\t\t\t<S ");
                if (i == start_index)
                    avio_printf(out, "t=\"%"PRId64"\" ", seg->time);
                avio_printf(out, "d=\"%d\" ", seg->duration);
                while (i + repeat + 1 < os->nb_segments && os->segments[i + repeat + 1]->duration == seg->duration)
                    repeat++;
                if (repeat > 0)
                    avio_printf(out, "r=\"%d\" ", repeat);
                avio_printf(out, "/>\n");
                i += 1 + repeat;
            }
            avio_printf(out, "\t\t\t\t\t</SegmentTimeline>\n");
        }
        avio_printf(out, "\t\t\t\t</SegmentTemplate>\n");
    } else if (c->single_file) {
        avio_printf(out, "\t\t\t\t<BaseURL>%s</BaseURL>\n", os->initfile);
        avio_printf(out, "\t\t\t\t<SegmentList timescale=\"%d\" duration=\"%d\" startNumber=\"%d\">\n", AV_TIME_BASE, c->last_duration, start_number);
        avio_printf(out, "\t\t\t\t\t<Initialization range=\"%"PRId64"-%"PRId64"\" />\n", os->init_start_pos, os->init_start_pos + os->init_range_length - 1);
        for (i = start_index; i < os->nb_segments; i++) {
            Segment *seg = os->segments[i];
            avio_printf(out, "\t\t\t\t\t<SegmentURL mediaRange=\"%"PRId64"-%"PRId64"\" ", seg->start_pos, seg->start_pos + seg->range_length - 1);
            if (seg->index_length)
                avio_printf(out, "indexRange=\"%"PRId64"-%"PRId64"\" ", seg->start_pos, seg->start_pos + seg->index_length - 1);
            avio_printf(out, "/>\n");
        }
        avio_printf(out, "\t\t\t\t</SegmentList>\n");
    } else {
        avio_printf(out, "\t\t\t\t<SegmentList timescale=\"%d\" duration=\"%d\" startNumber=\"%d\">\n", AV_TIME_BASE, c->last_duration, start_number);
        avio_printf(out, "\t\t\t\t\t<Initialization sourceURL=\"%s\" />\n", os->initfile);
        for (i = start_index; i < os->nb_segments; i++) {
            Segment *seg = os->segments[i];
            avio_printf(out, "\t\t\t\t\t<SegmentURL media=\"%s\" />\n", seg->file);
        }
        avio_printf(out, "\t\t\t\t</SegmentList>\n");
    }
}

static DASHTmplId dash_read_tmpl_id(const char *identifier, char *format_tag,
                                    size_t format_tag_size, const char **ptr) {
    const char *next_ptr;
    DASHTmplId id_type = DASH_TMPL_ID_UNDEFINED;

    if (av_strstart(identifier, "$$", &next_ptr)) {
        id_type = DASH_TMPL_ID_ESCAPE;
        *ptr = next_ptr;
    } else if (av_strstart(identifier, "$RepresentationID$", &next_ptr)) {
        id_type = DASH_TMPL_ID_REP_ID;
        // default to basic format, as $RepresentationID$ identifiers
        // are not allowed to have custom format-tags.
        av_strlcpy(format_tag, "%d", format_tag_size);
        *ptr = next_ptr;
    } else { // the following identifiers may have an explicit format_tag
        if (av_strstart(identifier, "$Number", &next_ptr))
            id_type = DASH_TMPL_ID_NUMBER;
        else if (av_strstart(identifier, "$Bandwidth", &next_ptr))
            id_type = DASH_TMPL_ID_BANDWIDTH;
        else if (av_strstart(identifier, "$Time", &next_ptr))
            id_type = DASH_TMPL_ID_TIME;
        else
            id_type = DASH_TMPL_ID_UNDEFINED;

        // next parse the dash format-tag and generate a c-string format tag
        // (next_ptr now points at the first '%' at the beginning of the format-tag)
        if (id_type != DASH_TMPL_ID_UNDEFINED) {
            const char *number_format = DASH_TMPL_ID_TIME ? "lld" : "d";
            if (next_ptr[0] == '$') { // no dash format-tag
                snprintf(format_tag, format_tag_size, "%%%s", number_format);
                *ptr = &next_ptr[1];
            } else {
                const char *width_ptr;
                // only tolerate single-digit width-field (i.e. up to 9-digit width)
                if (av_strstart(next_ptr, "%0", &width_ptr) &&
                    av_isdigit(width_ptr[0]) &&
                    av_strstart(&width_ptr[1], "d$", &next_ptr)) {
                    // yes, we're using a format tag to build format_tag.
                    snprintf(format_tag, format_tag_size, "%s%c%s", "%0", width_ptr[0], number_format);
                    *ptr = next_ptr;
                } else {
                    av_log(NULL, AV_LOG_WARNING, "Failed to parse format-tag beginning with %s. Expected either a "
                                                 "closing '$' character or a format-string like '%%0[width]d', "
                                                 "where width must be a single digit\n", next_ptr);
                    id_type = DASH_TMPL_ID_UNDEFINED;
                }
            }
        }
    }
    return id_type;
}

static void dash_fill_tmpl_params(char *dst, size_t buffer_size,
                                  const char *template, int rep_id,
                                  int number, int bit_rate,
                                  int64_t time) {
    int dst_pos = 0;
    const char *t_cur = template;
    while (dst_pos < buffer_size - 1 && *t_cur) {
        char format_tag[7]; // May be "%d", "%0Xd", or "%0Xlld" (for $Time$), where X is in [0-9]
        int n = 0;
        DASHTmplId id_type;
        const char *t_next = strchr(t_cur, '$'); // copy over everything up to the first '$' character
        if (t_next) {
            int num_copy_bytes = FFMIN(t_next - t_cur, buffer_size - dst_pos - 1);
            av_strlcpy(&dst[dst_pos], t_cur, num_copy_bytes + 1);
            // advance
            dst_pos += num_copy_bytes;
            t_cur = t_next;
        } else { // no more DASH identifiers to substitute - just copy the rest over and break
            av_strlcpy(&dst[dst_pos], t_cur, buffer_size - dst_pos);
            break;
        }

        if (dst_pos >= buffer_size - 1 || !*t_cur)
            break;

        // t_cur is now pointing to a '$' character
        id_type = dash_read_tmpl_id(t_cur, format_tag, sizeof(format_tag), &t_next);
        switch (id_type) {
        case DASH_TMPL_ID_ESCAPE:
            av_strlcpy(&dst[dst_pos], "$", 2);
            n = 1;
            break;
        case DASH_TMPL_ID_REP_ID:
            n = snprintf(&dst[dst_pos], buffer_size - dst_pos, format_tag, rep_id);
            break;
        case DASH_TMPL_ID_NUMBER:
            n = snprintf(&dst[dst_pos], buffer_size - dst_pos, format_tag, number);
            break;
        case DASH_TMPL_ID_BANDWIDTH:
            n = snprintf(&dst[dst_pos], buffer_size - dst_pos, format_tag, bit_rate);
            break;
        case DASH_TMPL_ID_TIME:
            n = snprintf(&dst[dst_pos], buffer_size - dst_pos, format_tag, time);
            break;
        case DASH_TMPL_ID_UNDEFINED:
            // copy over one byte and advance
            av_strlcpy(&dst[dst_pos], t_cur, 2);
            n = 1;
            t_next = &t_cur[1];
            break;
        }
        // t_next points just past the processed identifier
        // n is the number of bytes that were attempted to be written to dst
        // (may have failed to write all because buffer_size).

        // advance
        dst_pos += FFMIN(n, buffer_size - dst_pos - 1);
        t_cur = t_next;
    }
}

static char *xmlescape(const char *str) {
    int outlen = strlen(str)*3/2 + 6;
    char *out = av_realloc(NULL, outlen + 1);
    int pos = 0;
    if (!out)
        return NULL;
    for (; *str; str++) {
        if (pos + 6 > outlen) {
            char *tmp;
            outlen = 2 * outlen + 6;
            tmp = av_realloc(out, outlen + 1);
            if (!tmp) {
                av_free(out);
                return NULL;
            }
            out = tmp;
        }
        if (*str == '&') {
            memcpy(&out[pos], "&amp;", 5);
            pos += 5;
        } else if (*str == '<') {
            memcpy(&out[pos], "&lt;", 4);
            pos += 4;
        } else if (*str == '>') {
            memcpy(&out[pos], "&gt;", 4);
            pos += 4;
        } else if (*str == '\'') {
            memcpy(&out[pos], "&apos;", 6);
            pos += 6;
        } else if (*str == '\"') {
            memcpy(&out[pos], "&quot;", 6);
            pos += 6;
        } else {
            out[pos++] = *str;
        }
    }
    out[pos] = '\0';
    return out;
}

static void write_time(AVIOContext *out, int64_t time)
{
    int seconds = time / AV_TIME_BASE;
    int fractions = time % AV_TIME_BASE;
    int minutes = seconds / 60;
    int hours = minutes / 60;
    seconds %= 60;
    minutes %= 60;
    avio_printf(out, "PT");
    if (hours)
        avio_printf(out, "%dH", hours);
    if (hours || minutes)
        avio_printf(out, "%dM", minutes);
    avio_printf(out, "%d.%dS", seconds, fractions / (AV_TIME_BASE / 10));
}

static int write_manifest(AVFormatContext *s, int final)
{
    DASHContext *c = s->priv_data;
    AVIOContext *out;
    char temp_filename[1024];
    int ret, i;
    AVDictionaryEntry *title = av_dict_get(s->metadata, "title", NULL, 0);

    snprintf(temp_filename, sizeof(temp_filename), "%s.tmp", s->filename);
    ret = avio_open2(&out, temp_filename, AVIO_FLAG_WRITE, &s->interrupt_callback, NULL);
    if (ret < 0) {
        av_log(s, AV_LOG_ERROR, "Unable to open %s for writing\n", temp_filename);
        return ret;
    }
    avio_printf(out, "<?xml version=\"1.0\" encoding=\"utf-8\"?>\n");
    avio_printf(out, "<MPD xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\"\n"
                "\txmlns=\"urn:mpeg:dash:schema:mpd:2011\"\n"
                "\txmlns:xlink=\"http://www.w3.org/1999/xlink\"\n"
                "\txsi:schemaLocation=\"urn:mpeg:DASH:schema:MPD:2011 http://standards.iso.org/ittf/PubliclyAvailableStandards/MPEG-DASH_schema_files/DASH-MPD.xsd\"\n"
                "\tprofiles=\"urn:mpeg:dash:profile:isoff-live:2011\"\n"
                "\ttype=\"%s\"\n", final ? "static" : "dynamic");
    if (final) {
        avio_printf(out, "\tmediaPresentationDuration=\"");
        write_time(out, c->total_duration);
        avio_printf(out, "\"\n");
    } else {
        int update_period = c->last_duration / AV_TIME_BASE;
        if (c->use_template && !c->use_timeline)
            update_period = 500;
        avio_printf(out, "\tminimumUpdatePeriod=\"PT%dS\"\n", update_period);
        avio_printf(out, "\tsuggestedPresentationDelay=\"PT%dS\"\n", c->last_duration / AV_TIME_BASE);
        if (!c->availability_start_time[0] && s->nb_streams > 0 && c->streams[0].nb_segments > 0) {
            time_t t = time(NULL);
            struct tm *ptm, tmbuf;
            ptm = gmtime_r(&t, &tmbuf);
            if (ptm) {
                if (!strftime(c->availability_start_time, sizeof(c->availability_start_time),
                              "%Y-%m-%dT%H:%M:%S", ptm))
                    c->availability_start_time[0] = '\0';
            }
        }
        if (c->availability_start_time[0])
            avio_printf(out, "\tavailabilityStartTime=\"%s\"\n", c->availability_start_time);
        if (c->window_size && c->use_template) {
            avio_printf(out, "\ttimeShiftBufferDepth=\"");
            write_time(out, c->last_duration * c->window_size);
            avio_printf(out, "\"\n");
        }
    }
    avio_printf(out, "\tminBufferTime=\"");
    write_time(out, c->last_duration);
    avio_printf(out, "\">\n");
    avio_printf(out, "\t<ProgramInformation>\n");
    if (title) {
        char *escaped = xmlescape(title->value);
        avio_printf(out, "\t\t<Title>%s</Title>\n", escaped);
        av_free(escaped);
    }
    avio_printf(out, "\t</ProgramInformation>\n");
    if (c->window_size && s->nb_streams > 0 && c->streams[0].nb_segments > 0 && !c->use_template) {
        OutputStream *os = &c->streams[0];
        int start_index = FFMAX(os->nb_segments - c->window_size, 0);
        int64_t start_time = av_rescale_q(os->segments[start_index]->time, s->streams[0]->time_base, AV_TIME_BASE_Q);
        avio_printf(out, "\t<Period start=\"");
        write_time(out, start_time);
        avio_printf(out, "\">\n");
    } else {
        avio_printf(out, "\t<Period start=\"PT0.0S\">\n");
    }

    if (c->has_video) {
        avio_printf(out, "\t\t<AdaptationSet id=\"video\" segmentAlignment=\"true\" bitstreamSwitching=\"true\">\n");
        for (i = 0; i < s->nb_streams; i++) {
            AVStream *st = s->streams[i];
            OutputStream *os = &c->streams[i];
            if (s->streams[i]->codec->codec_type != AVMEDIA_TYPE_VIDEO)
                continue;
            avio_printf(out, "\t\t\t<Representation id=\"%d\" mimeType=\"video/mp4\" codecs=\"%s\"%s width=\"%d\" height=\"%d\">\n", i, os->codec_str, os->bandwidth_str, st->codec->width, st->codec->height);
            output_segment_list(&c->streams[i], out, c);
            avio_printf(out, "\t\t\t</Representation>\n");
        }
        avio_printf(out, "\t\t</AdaptationSet>\n");
    }
    if (c->has_audio) {
        avio_printf(out, "\t\t<AdaptationSet id=\"audio\" segmentAlignment=\"true\" bitstreamSwitching=\"true\">\n");
        for (i = 0; i < s->nb_streams; i++) {
            AVStream *st = s->streams[i];
            OutputStream *os = &c->streams[i];
            if (s->streams[i]->codec->codec_type != AVMEDIA_TYPE_AUDIO)
                continue;
            avio_printf(out, "\t\t\t<Representation id=\"%d\" mimeType=\"audio/mp4\" codecs=\"%s\"%s audioSamplingRate=\"%d\">\n", i, os->codec_str, os->bandwidth_str, st->codec->sample_rate);
            avio_printf(out, "\t\t\t\t<AudioChannelConfiguration schemeIdUri=\"urn:mpeg:dash:23003:3:audio_channel_configuration:2011\" value=\"%d\" />\n", st->codec->channels);
            output_segment_list(&c->streams[i], out, c);
            avio_printf(out, "\t\t\t</Representation>\n");
        }
        avio_printf(out, "\t\t</AdaptationSet>\n");
    }
    avio_printf(out, "\t</Period>\n");
    avio_printf(out, "</MPD>\n");
    avio_flush(out);
    avio_close(out);
    return ff_rename(temp_filename, s->filename);
}

static int dash_write_header(AVFormatContext *s)
{
    DASHContext *c = s->priv_data;
    int ret = 0, i;
    AVOutputFormat *oformat;
    char *ptr;
    char basename[1024];

    if (c->single_file_name)
        c->single_file = 1;
    if (c->single_file)
        c->use_template = 0;

    av_strlcpy(c->dirname, s->filename, sizeof(c->dirname));
    ptr = strrchr(c->dirname, '/');
    if (ptr) {
        av_strlcpy(basename, &ptr[1], sizeof(basename));
        ptr[1] = '\0';
    } else {
        c->dirname[0] = '\0';
        av_strlcpy(basename, s->filename, sizeof(basename));
    }

    ptr = strrchr(basename, '.');
    if (ptr)
        *ptr = '\0';

    oformat = av_guess_format("mp4", NULL, NULL);
    if (!oformat) {
        ret = AVERROR_MUXER_NOT_FOUND;
        goto fail;
    }

    c->streams = av_mallocz(sizeof(*c->streams) * s->nb_streams);
    if (!c->streams) {
        ret = AVERROR(ENOMEM);
        goto fail;
    }

    for (i = 0; i < s->nb_streams; i++) {
        OutputStream *os = &c->streams[i];
        AVFormatContext *ctx;
        AVStream *st;
        AVDictionary *opts = NULL;
        char filename[1024];

        os->bit_rate = s->streams[i]->codec->bit_rate;
        if (os->bit_rate) {
            snprintf(os->bandwidth_str, sizeof(os->bandwidth_str),
                     " bandwidth=\"%d\"", os->bit_rate);
        } else {
            int level = s->strict_std_compliance >= FF_COMPLIANCE_STRICT ?
                        AV_LOG_ERROR : AV_LOG_WARNING;
            av_log(s, level, "No bit rate set for stream %d\n", i);
            if (s->strict_std_compliance >= FF_COMPLIANCE_STRICT) {
                ret = AVERROR(EINVAL);
                goto fail;
            }
        }

        ctx = avformat_alloc_context();
        if (!ctx) {
            ret = AVERROR(ENOMEM);
            goto fail;
        }
        os->ctx = ctx;
        ctx->oformat = oformat;
        ctx->interrupt_callback = s->interrupt_callback;

        if (!(st = avformat_new_stream(ctx, NULL))) {
            ret = AVERROR(ENOMEM);
            goto fail;
        }
        avcodec_copy_context(st->codec, s->streams[i]->codec);
        st->sample_aspect_ratio = s->streams[i]->sample_aspect_ratio;
        st->time_base = s->streams[i]->time_base;
        ctx->avoid_negative_ts = s->avoid_negative_ts;

        ctx->pb = avio_alloc_context(os->iobuf, sizeof(os->iobuf), AVIO_FLAG_WRITE, os, NULL, dash_write, NULL);
        if (!ctx->pb) {
            ret = AVERROR(ENOMEM);
            goto fail;
        }

        if (c->single_file) {
            if (c->single_file_name)
                dash_fill_tmpl_params(os->initfile, sizeof(os->initfile), c->single_file_name, i, 0, os->bit_rate, 0);
            else
                snprintf(os->initfile, sizeof(os->initfile), "%s-stream%d.m4s", basename, i);
        } else {
            dash_fill_tmpl_params(os->initfile, sizeof(os->initfile), c->init_seg_name, i, 0, os->bit_rate, 0);
        }
        snprintf(filename, sizeof(filename), "%s%s", c->dirname, os->initfile);
        ret = ffurl_open(&os->out, filename, AVIO_FLAG_WRITE, &s->interrupt_callback, NULL);
        if (ret < 0)
            goto fail;
        os->init_start_pos = 0;

        av_dict_set(&opts, "movflags", "frag_custom+dash", 0);
        if ((ret = avformat_write_header(ctx, &opts)) < 0) {
             goto fail;
        }
        os->ctx_inited = 1;
        avio_flush(ctx->pb);
        av_dict_free(&opts);

        if (c->single_file) {
            os->init_range_length = avio_tell(ctx->pb);
        } else {
            ffurl_close(os->out);
            os->out = NULL;
        }

        s->streams[i]->time_base = st->time_base;
        // If the muxer wants to shift timestamps, request to have them shifted
        // already before being handed to this muxer, so we don't have mismatches
        // between the MPD and the actual segments.
        s->avoid_negative_ts = ctx->avoid_negative_ts;
        if (st->codec->codec_type == AVMEDIA_TYPE_VIDEO)
            c->has_video = 1;
        else if (st->codec->codec_type == AVMEDIA_TYPE_AUDIO)
            c->has_audio = 1;

        set_codec_str(s, os->ctx->streams[0]->codec, os->codec_str, sizeof(os->codec_str));
        os->first_dts = AV_NOPTS_VALUE;
        os->segment_index = 1;
    }

    if (!c->has_video && c->min_seg_duration <= 0) {
        av_log(s, AV_LOG_WARNING, "no video stream and no min seg duration set\n");
        ret = AVERROR(EINVAL);
    }
    ret = write_manifest(s, 0);

fail:
    if (ret)
        dash_free(s);
    return ret;
}

static int add_segment(OutputStream *os, const char *file,
                       int64_t time, int duration,
                       int64_t start_pos, int64_t range_length,
                       int64_t index_length)
{
    int err;
    Segment *seg;
    if (os->nb_segments >= os->segments_size) {
        os->segments_size = (os->segments_size + 1) * 2;
        if ((err = av_reallocp(&os->segments, sizeof(*os->segments) *
                               os->segments_size)) < 0) {
            os->segments_size = 0;
            os->nb_segments = 0;
            return err;
        }
    }
    seg = av_mallocz(sizeof(*seg));
    if (!seg)
        return AVERROR(ENOMEM);
    av_strlcpy(seg->file, file, sizeof(seg->file));
    seg->time = time;
    seg->duration = duration;
    seg->start_pos = start_pos;
    seg->range_length = range_length;
    seg->index_length = index_length;
    os->segments[os->nb_segments++] = seg;
    os->segment_index++;
    return 0;
}

static void write_styp(AVIOContext *pb)
{
    avio_wb32(pb, 24);
    ffio_wfourcc(pb, "styp");
    ffio_wfourcc(pb, "msdh");
    avio_wb32(pb, 0); /* minor */
    ffio_wfourcc(pb, "msdh");
    ffio_wfourcc(pb, "msix");
}

static void find_index_range(AVFormatContext *s, const char *dirname,
                             const char *filename, int64_t pos,
                             int *index_length)
{
    char full_path[1024];
    uint8_t buf[8];
    URLContext *fd;
    int ret;

    snprintf(full_path, sizeof(full_path), "%s%s", dirname, filename);
    ret = ffurl_open(&fd, full_path, AVIO_FLAG_READ, &s->interrupt_callback, NULL);
    if (ret < 0)
        return;
    if (ffurl_seek(fd, pos, SEEK_SET) != pos) {
        ffurl_close(fd);
        return;
    }
    ret = ffurl_read(fd, buf, 8);
    ffurl_close(fd);
    if (ret < 8)
        return;
    if (AV_RL32(&buf[4]) != MKTAG('s', 'i', 'd', 'x'))
        return;
    *index_length = AV_RB32(&buf[0]);
}

static int dash_flush(AVFormatContext *s, int final, int stream)
{
    DASHContext *c = s->priv_data;
    int i, ret = 0;
    int cur_flush_segment_index = 0;
    if (stream >= 0)
        cur_flush_segment_index = c->streams[stream].segment_index;

    for (i = 0; i < s->nb_streams; i++) {
        OutputStream *os = &c->streams[i];
        char filename[1024] = "", full_path[1024], temp_path[1024];
        int64_t start_pos = avio_tell(os->ctx->pb);
        int range_length, index_length = 0;

        if (!os->packets_written)
            continue;

        // Flush the single stream that got a keyframe right now.
        // Flush all audio streams as well, in sync with video keyframes,
        // but not the other video streams.
        if (stream >= 0 && i != stream) {
            if (s->streams[i]->codec->codec_type != AVMEDIA_TYPE_AUDIO)
                continue;
            // Make sure we don't flush audio streams multiple times, when
            // all video streams are flushed one at a time.
            if (c->has_video && os->segment_index > cur_flush_segment_index)
                continue;
        }

        if (!c->single_file) {
            dash_fill_tmpl_params(filename, sizeof(filename), c->media_seg_name, i, os->segment_index, os->bit_rate, os->start_dts);
            snprintf(full_path, sizeof(full_path), "%s%s", c->dirname, filename);
            snprintf(temp_path, sizeof(temp_path), "%s.tmp", full_path);
            ret = ffurl_open(&os->out, temp_path, AVIO_FLAG_WRITE, &s->interrupt_callback, NULL);
            if (ret < 0)
                break;
            write_styp(os->ctx->pb);
        }
        av_write_frame(os->ctx, NULL);
        avio_flush(os->ctx->pb);
        os->packets_written = 0;

        range_length = avio_tell(os->ctx->pb) - start_pos;
        if (c->single_file) {
            find_index_range(s, c->dirname, os->initfile, start_pos, &index_length);
        } else {
            ffurl_close(os->out);
            os->out = NULL;
            ret = ff_rename(temp_path, full_path);
            if (ret < 0)
                break;
        }
        add_segment(os, filename, os->start_dts, os->end_dts - os->start_dts, start_pos, range_length, index_length);
    }

    if (c->window_size || (final && c->remove_at_exit)) {
        for (i = 0; i < s->nb_streams; i++) {
            OutputStream *os = &c->streams[i];
            int j;
            int remove = os->nb_segments - c->window_size - c->extra_window_size;
            if (final && c->remove_at_exit)
                remove = os->nb_segments;
            if (remove > 0) {
                for (j = 0; j < remove; j++) {
                    char filename[1024];
                    snprintf(filename, sizeof(filename), "%s%s", c->dirname, os->segments[j]->file);
                    unlink(filename);
                    av_free(os->segments[j]);
                }
                os->nb_segments -= remove;
                memmove(os->segments, os->segments + remove, os->nb_segments * sizeof(*os->segments));
            }
        }
    }

    if (ret >= 0)
        ret = write_manifest(s, final);
    return ret;
}

static int dash_write_packet(AVFormatContext *s, AVPacket *pkt)
{
    DASHContext *c = s->priv_data;
    AVStream *st = s->streams[pkt->stream_index];
    OutputStream *os = &c->streams[pkt->stream_index];
    int64_t seg_end_duration = (os->segment_index) * (int64_t) c->min_seg_duration;
    int ret;

    // If forcing the stream to start at 0, the mp4 muxer will set the start
    // timestamps to 0. Do the same here, to avoid mismatches in duration/timestamps.
    if (os->first_dts == AV_NOPTS_VALUE &&
        s->avoid_negative_ts == AVFMT_AVOID_NEG_TS_MAKE_ZERO) {
        pkt->pts -= pkt->dts;
        pkt->dts  = 0;
    }

    if (os->first_dts == AV_NOPTS_VALUE)
        os->first_dts = pkt->dts;

    if ((!c->has_video || st->codec->codec_type == AVMEDIA_TYPE_VIDEO) &&
        pkt->flags & AV_PKT_FLAG_KEY && os->packets_written &&
        av_compare_ts(pkt->dts - os->first_dts, st->time_base,
                      seg_end_duration, AV_TIME_BASE_Q) >= 0) {
        int64_t prev_duration = c->last_duration;

        c->last_duration = av_rescale_q(pkt->dts - os->start_dts,
                                        st->time_base,
                                        AV_TIME_BASE_Q);
        c->total_duration = av_rescale_q(pkt->dts - os->first_dts,
                                         st->time_base,
                                         AV_TIME_BASE_Q);

        if ((!c->use_timeline || !c->use_template) && prev_duration) {
            if (c->last_duration < prev_duration*9/10 ||
                c->last_duration > prev_duration*11/10) {
                av_log(s, AV_LOG_WARNING,
                       "Segment durations differ too much, enable use_timeline "
                       "and use_template, or keep a stricter keyframe interval\n");
            }
        }

        if ((ret = dash_flush(s, 0, pkt->stream_index)) < 0)
            return ret;
    }

    if (!os->packets_written)
        os->start_dts = pkt->dts;
    os->end_dts = pkt->dts + pkt->duration;
    os->packets_written++;
    return ff_write_chained(os->ctx, 0, pkt, s);
}

static int dash_write_trailer(AVFormatContext *s)
{
    DASHContext *c = s->priv_data;

    if (s->nb_streams > 0) {
        OutputStream *os = &c->streams[0];
        // If no segments have been written so far, try to do a crude
        // guess of the segment duration
        if (!c->last_duration)
            c->last_duration = av_rescale_q(os->end_dts - os->start_dts,
                                            s->streams[0]->time_base,
                                            AV_TIME_BASE_Q);
        c->total_duration = av_rescale_q(os->end_dts - os->first_dts,
                                         s->streams[0]->time_base,
                                         AV_TIME_BASE_Q);
    }
    dash_flush(s, 1, -1);

    if (c->remove_at_exit) {
        char filename[1024];
        int i;
        for (i = 0; i < s->nb_streams; i++) {
            OutputStream *os = &c->streams[i];
            snprintf(filename, sizeof(filename), "%s%s", c->dirname, os->initfile);
            unlink(filename);
        }
        unlink(s->filename);
    }

    dash_free(s);
    return 0;
}

#define OFFSET(x) offsetof(DASHContext, x)
#define E AV_OPT_FLAG_ENCODING_PARAM
static const AVOption options[] = {
    { "window_size", "number of segments kept in the manifest", OFFSET(window_size), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, E },
    { "extra_window_size", "number of segments kept outside of the manifest before removing from disk", OFFSET(extra_window_size), AV_OPT_TYPE_INT, { .i64 = 5 }, 0, INT_MAX, E },
    { "min_seg_duration", "minimum segment duration (in microseconds)", OFFSET(min_seg_duration), AV_OPT_TYPE_INT64, { .i64 = 5000000 }, 0, INT_MAX, E },
    { "remove_at_exit", "remove all segments when finished", OFFSET(remove_at_exit), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 1, E },
    { "use_template", "Use SegmentTemplate instead of SegmentList", OFFSET(use_template), AV_OPT_TYPE_INT, { .i64 = 1 }, 0, 1, E },
    { "use_timeline", "Use SegmentTimeline in SegmentTemplate", OFFSET(use_timeline), AV_OPT_TYPE_INT, { .i64 = 1 }, 0, 1, E },
    { "single_file", "Store all segments in one file, accessed using byte ranges", OFFSET(single_file), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 1, E },
    { "single_file_name", "DASH-templated name to be used for baseURL. Implies storing all segments in one file, accessed using byte ranges", OFFSET(single_file_name), AV_OPT_TYPE_STRING, { .str = NULL }, 0, 0, E },
    { "init_seg_name", "DASH-templated name to used for the initialization segment", OFFSET(init_seg_name), AV_OPT_TYPE_STRING, {.str = "init-stream$RepresentationID$.m4s"},  0, 0, E },
    { "media_seg_name", "DASH-templated name to used for the media segments", OFFSET(media_seg_name), AV_OPT_TYPE_STRING, {.str = "chunk-stream$RepresentationID$-$Number%05d$.m4s"},  0, 0, E },
    { NULL },
};

static const AVClass dash_class = {
    .class_name = "dash muxer",
    .item_name  = av_default_item_name,
    .option     = options,
    .version    = LIBAVUTIL_VERSION_INT,
};

AVOutputFormat ff_dash_muxer = {
    .name           = "dash",
    .long_name      = NULL_IF_CONFIG_SMALL("DASH Muxer"),
    .priv_data_size = sizeof(DASHContext),
    .audio_codec    = AV_CODEC_ID_AAC,
    .video_codec    = AV_CODEC_ID_H264,
    .flags          = AVFMT_GLOBALHEADER | AVFMT_NOFILE | AVFMT_TS_NEGATIVE,
    .write_header   = dash_write_header,
    .write_packet   = dash_write_packet,
    .write_trailer  = dash_write_trailer,
    .codec_tag      = (const AVCodecTag* const []){ ff_mp4_obj_type, 0 },
    .priv_class     = &dash_class,
};