Merge commit '675ac56b7ee0f204963fde55295197c5df80aa91'
[ffmpeg.git] / libavformat / dashenc.c
1 /*
2  * MPEG-DASH ISO BMFF segmenter
3  * Copyright (c) 2014 Martin Storsjo
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21
22 #include "config.h"
23 #if HAVE_UNISTD_H
24 #include <unistd.h>
25 #endif
26
27 #include "libavutil/avstring.h"
28 #include "libavutil/intreadwrite.h"
29 #include "libavutil/mathematics.h"
30 #include "libavutil/opt.h"
31 #include "libavutil/time_internal.h"
32
33 #include "avc.h"
34 #include "avformat.h"
35 #include "avio_internal.h"
36 #include "internal.h"
37 #include "isom.h"
38 #include "os_support.h"
39 #include "url.h"
40
41 typedef struct Segment {
42     char file[1024];
43     int64_t start_pos;
44     int range_length, index_length;
45     int64_t time;
46     int duration;
47     int n;
48 } Segment;
49
50 typedef struct OutputStream {
51     AVFormatContext *ctx;
52     int ctx_inited;
53     uint8_t iobuf[32768];
54     URLContext *out;
55     int packets_written;
56     char initfile[1024];
57     int64_t init_start_pos;
58     int init_range_length;
59     int nb_segments, segments_size, segment_index;
60     Segment **segments;
61     int64_t first_dts, start_dts, end_dts;
62     char bandwidth_str[64];
63
64     char codec_str[100];
65 } OutputStream;
66
67 typedef struct DASHContext {
68     const AVClass *class;  /* Class for private options. */
69     int window_size;
70     int extra_window_size;
71     int min_seg_duration;
72     int remove_at_exit;
73     int use_template;
74     int use_timeline;
75     int single_file;
76     OutputStream *streams;
77     int has_video, has_audio;
78     int last_duration;
79     int total_duration;
80     char availability_start_time[100];
81     char dirname[1024];
82 } DASHContext;
83
84 static int dash_write(void *opaque, uint8_t *buf, int buf_size)
85 {
86     OutputStream *os = opaque;
87     if (os->out)
88         ffurl_write(os->out, buf, buf_size);
89     return buf_size;
90 }
91
92 // RFC 6381
93 static void set_codec_str(AVFormatContext *s, AVCodecContext *codec,
94                           char *str, int size)
95 {
96     const AVCodecTag *tags[2] = { NULL, NULL };
97     uint32_t tag;
98     if (codec->codec_type == AVMEDIA_TYPE_VIDEO)
99         tags[0] = ff_codec_movvideo_tags;
100     else if (codec->codec_type == AVMEDIA_TYPE_AUDIO)
101         tags[0] = ff_codec_movaudio_tags;
102     else
103         return;
104
105     tag = av_codec_get_tag(tags, codec->codec_id);
106     if (!tag)
107         return;
108     if (size < 5)
109         return;
110
111     AV_WL32(str, tag);
112     str[4] = '\0';
113     if (!strcmp(str, "mp4a") || !strcmp(str, "mp4v")) {
114         uint32_t oti;
115         tags[0] = ff_mp4_obj_type;
116         oti = av_codec_get_tag(tags, codec->codec_id);
117         if (oti)
118             av_strlcatf(str, size, ".%02x", oti);
119         else
120             return;
121
122         if (tag == MKTAG('m', 'p', '4', 'a')) {
123             if (codec->extradata_size >= 2) {
124                 int aot = codec->extradata[0] >> 3;
125                 if (aot == 31)
126                     aot = ((AV_RB16(codec->extradata) >> 5) & 0x3f) + 32;
127                 av_strlcatf(str, size, ".%d", aot);
128             }
129         } else if (tag == MKTAG('m', 'p', '4', 'v')) {
130             // Unimplemented, should output ProfileLevelIndication as a decimal number
131             av_log(s, AV_LOG_WARNING, "Incomplete RFC 6381 codec string for mp4v\n");
132         }
133     } else if (!strcmp(str, "avc1")) {
134         uint8_t *tmpbuf = NULL;
135         uint8_t *extradata = codec->extradata;
136         int extradata_size = codec->extradata_size;
137         if (!extradata_size)
138             return;
139         if (extradata[0] != 1) {
140             AVIOContext *pb;
141             if (avio_open_dyn_buf(&pb) < 0)
142                 return;
143             if (ff_isom_write_avcc(pb, extradata, extradata_size) < 0) {
144                 avio_close_dyn_buf(pb, &tmpbuf);
145                 av_free(tmpbuf);
146                 return;
147             }
148             extradata_size = avio_close_dyn_buf(pb, &extradata);
149             tmpbuf = extradata;
150         }
151
152         if (extradata_size >= 4)
153             av_strlcatf(str, size, ".%02x%02x%02x",
154                         extradata[1], extradata[2], extradata[3]);
155         av_free(tmpbuf);
156     }
157 }
158
159 static void dash_free(AVFormatContext *s)
160 {
161     DASHContext *c = s->priv_data;
162     int i, j;
163     if (!c->streams)
164         return;
165     for (i = 0; i < s->nb_streams; i++) {
166         OutputStream *os = &c->streams[i];
167         if (os->ctx && os->ctx_inited)
168             av_write_trailer(os->ctx);
169         if (os->ctx && os->ctx->pb)
170             av_free(os->ctx->pb);
171         ffurl_close(os->out);
172         os->out =  NULL;
173         if (os->ctx)
174             avformat_free_context(os->ctx);
175         for (j = 0; j < os->nb_segments; j++)
176             av_free(os->segments[j]);
177         av_free(os->segments);
178     }
179     av_freep(&c->streams);
180 }
181
182 static void output_segment_list(OutputStream *os, AVIOContext *out, DASHContext *c)
183 {
184     int i, start_index = 0, start_number = 1;
185     if (c->window_size) {
186         start_index  = FFMAX(os->nb_segments   - c->window_size, 0);
187         start_number = FFMAX(os->segment_index - c->window_size, 1);
188     }
189
190     if (c->use_template) {
191         int timescale = c->use_timeline ? os->ctx->streams[0]->time_base.den : AV_TIME_BASE;
192         avio_printf(out, "\t\t\t\t<SegmentTemplate timescale=\"%d\" ", timescale);
193         if (!c->use_timeline)
194             avio_printf(out, "duration=\"%d\" ", c->last_duration);
195         avio_printf(out, "initialization=\"init-stream$RepresentationID$.m4s\" media=\"chunk-stream$RepresentationID$-$Number%%05d$.m4s\" startNumber=\"%d\">\n", c->use_timeline ? start_number : 1);
196         if (c->use_timeline) {
197             avio_printf(out, "\t\t\t\t\t<SegmentTimeline>\n");
198             for (i = start_index; i < os->nb_segments; ) {
199                 Segment *seg = os->segments[i];
200                 int repeat = 0;
201                 avio_printf(out, "\t\t\t\t\t\t<S ");
202                 if (i == start_index)
203                     avio_printf(out, "t=\"%"PRId64"\" ", seg->time);
204                 avio_printf(out, "d=\"%d\" ", seg->duration);
205                 while (i + repeat + 1 < os->nb_segments && os->segments[i + repeat + 1]->duration == seg->duration)
206                     repeat++;
207                 if (repeat > 0)
208                     avio_printf(out, "r=\"%d\" ", repeat);
209                 avio_printf(out, "/>\n");
210                 i += 1 + repeat;
211             }
212             avio_printf(out, "\t\t\t\t\t</SegmentTimeline>\n");
213         }
214         avio_printf(out, "\t\t\t\t</SegmentTemplate>\n");
215     } else if (c->single_file) {
216         avio_printf(out, "\t\t\t\t<BaseURL>%s</BaseURL>\n", os->initfile);
217         avio_printf(out, "\t\t\t\t<SegmentList timescale=\"%d\" duration=\"%d\" startNumber=\"%d\">\n", AV_TIME_BASE, c->last_duration, start_number);
218         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);
219         for (i = start_index; i < os->nb_segments; i++) {
220             Segment *seg = os->segments[i];
221             avio_printf(out, "\t\t\t\t\t<SegmentURL mediaRange=\"%"PRId64"-%"PRId64"\" ", seg->start_pos, seg->start_pos + seg->range_length - 1);
222             if (seg->index_length)
223                 avio_printf(out, "indexRange=\"%"PRId64"-%"PRId64"\" ", seg->start_pos, seg->start_pos + seg->index_length - 1);
224             avio_printf(out, "/>\n");
225         }
226         avio_printf(out, "\t\t\t\t</SegmentList>\n");
227     } else {
228         avio_printf(out, "\t\t\t\t<SegmentList timescale=\"%d\" duration=\"%d\" startNumber=\"%d\">\n", AV_TIME_BASE, c->last_duration, start_number);
229         avio_printf(out, "\t\t\t\t\t<Initialization sourceURL=\"%s\" />\n", os->initfile);
230         for (i = start_index; i < os->nb_segments; i++) {
231             Segment *seg = os->segments[i];
232             avio_printf(out, "\t\t\t\t\t<SegmentURL media=\"%s\" />\n", seg->file);
233         }
234         avio_printf(out, "\t\t\t\t</SegmentList>\n");
235     }
236 }
237
238 static char *xmlescape(const char *str) {
239     int outlen = strlen(str)*3/2 + 6;
240     char *out = av_realloc(NULL, outlen + 1);
241     int pos = 0;
242     if (!out)
243         return NULL;
244     for (; *str; str++) {
245         if (pos + 6 > outlen) {
246             char *tmp;
247             outlen = 2 * outlen + 6;
248             tmp = av_realloc(out, outlen + 1);
249             if (!tmp) {
250                 av_free(out);
251                 return NULL;
252             }
253             out = tmp;
254         }
255         if (*str == '&') {
256             memcpy(&out[pos], "&amp;", 5);
257             pos += 5;
258         } else if (*str == '<') {
259             memcpy(&out[pos], "&lt;", 4);
260             pos += 4;
261         } else if (*str == '>') {
262             memcpy(&out[pos], "&gt;", 4);
263             pos += 4;
264         } else if (*str == '\'') {
265             memcpy(&out[pos], "&apos;", 6);
266             pos += 6;
267         } else if (*str == '\"') {
268             memcpy(&out[pos], "&quot;", 6);
269             pos += 6;
270         } else {
271             out[pos++] = *str;
272         }
273     }
274     out[pos] = '\0';
275     return out;
276 }
277
278 static void write_time(AVIOContext *out, int64_t time)
279 {
280     int seconds = time / AV_TIME_BASE;
281     int fractions = time % AV_TIME_BASE;
282     int minutes = seconds / 60;
283     int hours = minutes / 60;
284     seconds %= 60;
285     minutes %= 60;
286     avio_printf(out, "PT");
287     if (hours)
288         avio_printf(out, "%dH", hours);
289     if (hours || minutes)
290         avio_printf(out, "%dM", minutes);
291     avio_printf(out, "%d.%dS", seconds, fractions / (AV_TIME_BASE / 10));
292 }
293
294 static int write_manifest(AVFormatContext *s, int final)
295 {
296     DASHContext *c = s->priv_data;
297     AVIOContext *out;
298     char temp_filename[1024];
299     int ret, i;
300     AVDictionaryEntry *title = av_dict_get(s->metadata, "title", NULL, 0);
301
302     snprintf(temp_filename, sizeof(temp_filename), "%s.tmp", s->filename);
303     ret = avio_open2(&out, temp_filename, AVIO_FLAG_WRITE, &s->interrupt_callback, NULL);
304     if (ret < 0) {
305         av_log(s, AV_LOG_ERROR, "Unable to open %s for writing\n", temp_filename);
306         return ret;
307     }
308     avio_printf(out, "<?xml version=\"1.0\" encoding=\"utf-8\"?>\n");
309     avio_printf(out, "<MPD xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\"\n"
310                 "\txmlns=\"urn:mpeg:dash:schema:mpd:2011\"\n"
311                 "\txmlns:xlink=\"http://www.w3.org/1999/xlink\"\n"
312                 "\txsi:schemaLocation=\"urn:mpeg:DASH:schema:MPD:2011 http://standards.iso.org/ittf/PubliclyAvailableStandards/MPEG-DASH_schema_files/DASH-MPD.xsd\"\n"
313                 "\tprofiles=\"urn:mpeg:dash:profile:isoff-live:2011\"\n"
314                 "\ttype=\"%s\"\n", final ? "static" : "dynamic");
315     if (final) {
316         avio_printf(out, "\tmediaPresentationDuration=\"");
317         write_time(out, c->total_duration);
318         avio_printf(out, "\"\n");
319     } else {
320         int update_period = c->last_duration / AV_TIME_BASE;
321         if (c->use_template && !c->use_timeline)
322             update_period = 500;
323         avio_printf(out, "\tminimumUpdatePeriod=\"PT%dS\"\n", update_period);
324         avio_printf(out, "\tsuggestedPresentationDelay=\"PT%dS\"\n", c->last_duration / AV_TIME_BASE);
325         if (!c->availability_start_time[0] && s->nb_streams > 0 && c->streams[0].nb_segments > 0) {
326             time_t t = time(NULL);
327             struct tm *ptm, tmbuf;
328             ptm = gmtime_r(&t, &tmbuf);
329             if (ptm) {
330                 if (!strftime(c->availability_start_time, sizeof(c->availability_start_time),
331                               "%Y-%m-%dT%H:%M:%S", ptm))
332                     c->availability_start_time[0] = '\0';
333             }
334         }
335         if (c->availability_start_time[0])
336             avio_printf(out, "\tavailabilityStartTime=\"%s\"\n", c->availability_start_time);
337         if (c->window_size && c->use_template) {
338             avio_printf(out, "\ttimeShiftBufferDepth=\"");
339             write_time(out, c->last_duration * c->window_size);
340             avio_printf(out, "\"\n");
341         }
342     }
343     avio_printf(out, "\tminBufferTime=\"");
344     write_time(out, c->last_duration);
345     avio_printf(out, "\">\n");
346     avio_printf(out, "\t<ProgramInformation>\n");
347     if (title) {
348         char *escaped = xmlescape(title->value);
349         avio_printf(out, "\t\t<Title>%s</Title>\n", escaped);
350         av_free(escaped);
351     }
352     avio_printf(out, "\t</ProgramInformation>\n");
353     if (c->window_size && s->nb_streams > 0 && c->streams[0].nb_segments > 0 && !c->use_template) {
354         OutputStream *os = &c->streams[0];
355         int start_index = FFMAX(os->nb_segments - c->window_size, 0);
356         int64_t start_time = av_rescale_q(os->segments[start_index]->time, s->streams[0]->time_base, AV_TIME_BASE_Q);
357         avio_printf(out, "\t<Period start=\"");
358         write_time(out, start_time);
359         avio_printf(out, "\">\n");
360     } else {
361         avio_printf(out, "\t<Period start=\"PT0.0S\">\n");
362     }
363
364     if (c->has_video) {
365         avio_printf(out, "\t\t<AdaptationSet id=\"video\" segmentAlignment=\"true\" bitstreamSwitching=\"true\">\n");
366         for (i = 0; i < s->nb_streams; i++) {
367             AVStream *st = s->streams[i];
368             OutputStream *os = &c->streams[i];
369             if (s->streams[i]->codec->codec_type != AVMEDIA_TYPE_VIDEO)
370                 continue;
371             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);
372             output_segment_list(&c->streams[i], out, c);
373             avio_printf(out, "\t\t\t</Representation>\n");
374         }
375         avio_printf(out, "\t\t</AdaptationSet>\n");
376     }
377     if (c->has_audio) {
378         avio_printf(out, "\t\t<AdaptationSet id=\"audio\" segmentAlignment=\"true\" bitstreamSwitching=\"true\">\n");
379         for (i = 0; i < s->nb_streams; i++) {
380             AVStream *st = s->streams[i];
381             OutputStream *os = &c->streams[i];
382             if (s->streams[i]->codec->codec_type != AVMEDIA_TYPE_AUDIO)
383                 continue;
384             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);
385             avio_printf(out, "\t\t\t\t<AudioChannelConfiguration schemeIdUri=\"urn:mpeg:dash:23003:3:audio_channel_configuration:2011\" value=\"%d\" />\n", st->codec->channels);
386             output_segment_list(&c->streams[i], out, c);
387             avio_printf(out, "\t\t\t</Representation>\n");
388         }
389         avio_printf(out, "\t\t</AdaptationSet>\n");
390     }
391     avio_printf(out, "\t</Period>\n");
392     avio_printf(out, "</MPD>\n");
393     avio_flush(out);
394     avio_close(out);
395     return ff_rename(temp_filename, s->filename, s);
396 }
397
398 static int dash_write_header(AVFormatContext *s)
399 {
400     DASHContext *c = s->priv_data;
401     int ret = 0, i;
402     AVOutputFormat *oformat;
403     char *ptr;
404     char basename[1024];
405
406     if (c->single_file)
407         c->use_template = 0;
408
409     av_strlcpy(c->dirname, s->filename, sizeof(c->dirname));
410     ptr = strrchr(c->dirname, '/');
411     if (ptr) {
412         av_strlcpy(basename, &ptr[1], sizeof(basename));
413         ptr[1] = '\0';
414     } else {
415         c->dirname[0] = '\0';
416         av_strlcpy(basename, s->filename, sizeof(basename));
417     }
418
419     ptr = strrchr(basename, '.');
420     if (ptr)
421         *ptr = '\0';
422
423     oformat = av_guess_format("mp4", NULL, NULL);
424     if (!oformat) {
425         ret = AVERROR_MUXER_NOT_FOUND;
426         goto fail;
427     }
428
429     c->streams = av_mallocz(sizeof(*c->streams) * s->nb_streams);
430     if (!c->streams) {
431         ret = AVERROR(ENOMEM);
432         goto fail;
433     }
434
435     for (i = 0; i < s->nb_streams; i++) {
436         OutputStream *os = &c->streams[i];
437         AVFormatContext *ctx;
438         AVStream *st;
439         AVDictionary *opts = NULL;
440         char filename[1024];
441
442         int bit_rate = s->streams[i]->codec->bit_rate ?
443                        s->streams[i]->codec->bit_rate :
444                        s->streams[i]->codec->rc_max_rate;
445         if (bit_rate) {
446             snprintf(os->bandwidth_str, sizeof(os->bandwidth_str),
447                      " bandwidth=\"%d\"", bit_rate);
448         } else {
449             int level = s->strict_std_compliance >= FF_COMPLIANCE_STRICT ?
450                         AV_LOG_ERROR : AV_LOG_WARNING;
451             av_log(s, level, "No bit rate set for stream %d\n", i);
452             if (s->strict_std_compliance >= FF_COMPLIANCE_STRICT) {
453                 ret = AVERROR(EINVAL);
454                 goto fail;
455             }
456         }
457
458         ctx = avformat_alloc_context();
459         if (!ctx) {
460             ret = AVERROR(ENOMEM);
461             goto fail;
462         }
463         os->ctx = ctx;
464         ctx->oformat = oformat;
465         ctx->interrupt_callback = s->interrupt_callback;
466
467         if (!(st = avformat_new_stream(ctx, NULL))) {
468             ret = AVERROR(ENOMEM);
469             goto fail;
470         }
471         avcodec_copy_context(st->codec, s->streams[i]->codec);
472         st->sample_aspect_ratio = s->streams[i]->sample_aspect_ratio;
473         st->time_base = s->streams[i]->time_base;
474         ctx->avoid_negative_ts = s->avoid_negative_ts;
475
476         ctx->pb = avio_alloc_context(os->iobuf, sizeof(os->iobuf), AVIO_FLAG_WRITE, os, NULL, dash_write, NULL);
477         if (!ctx->pb) {
478             ret = AVERROR(ENOMEM);
479             goto fail;
480         }
481
482         if (c->single_file)
483             snprintf(os->initfile, sizeof(os->initfile), "%s-stream%d.m4s", basename, i);
484         else
485             snprintf(os->initfile, sizeof(os->initfile), "init-stream%d.m4s", i);
486         snprintf(filename, sizeof(filename), "%s%s", c->dirname, os->initfile);
487         ret = ffurl_open(&os->out, filename, AVIO_FLAG_WRITE, &s->interrupt_callback, NULL);
488         if (ret < 0)
489             goto fail;
490         os->init_start_pos = 0;
491
492         av_dict_set(&opts, "movflags", "frag_custom+dash", 0);
493         if ((ret = avformat_write_header(ctx, &opts)) < 0) {
494              goto fail;
495         }
496         os->ctx_inited = 1;
497         avio_flush(ctx->pb);
498         av_dict_free(&opts);
499
500         if (c->single_file) {
501             os->init_range_length = avio_tell(ctx->pb);
502         } else {
503             ffurl_close(os->out);
504             os->out = NULL;
505         }
506
507         s->streams[i]->time_base = st->time_base;
508         // If the muxer wants to shift timestamps, request to have them shifted
509         // already before being handed to this muxer, so we don't have mismatches
510         // between the MPD and the actual segments.
511         s->avoid_negative_ts = ctx->avoid_negative_ts;
512         if (st->codec->codec_type == AVMEDIA_TYPE_VIDEO)
513             c->has_video = 1;
514         else if (st->codec->codec_type == AVMEDIA_TYPE_AUDIO)
515             c->has_audio = 1;
516
517         set_codec_str(s, os->ctx->streams[0]->codec, os->codec_str, sizeof(os->codec_str));
518         os->first_dts = AV_NOPTS_VALUE;
519         os->segment_index = 1;
520     }
521
522     if (!c->has_video && c->min_seg_duration <= 0) {
523         av_log(s, AV_LOG_WARNING, "no video stream and no min seg duration set\n");
524         ret = AVERROR(EINVAL);
525     }
526     ret = write_manifest(s, 0);
527
528 fail:
529     if (ret)
530         dash_free(s);
531     return ret;
532 }
533
534 static int add_segment(OutputStream *os, const char *file,
535                        int64_t time, int duration,
536                        int64_t start_pos, int64_t range_length,
537                        int64_t index_length)
538 {
539     int err;
540     Segment *seg;
541     if (os->nb_segments >= os->segments_size) {
542         os->segments_size = (os->segments_size + 1) * 2;
543         if ((err = av_reallocp(&os->segments, sizeof(*os->segments) *
544                                os->segments_size)) < 0) {
545             os->segments_size = 0;
546             os->nb_segments = 0;
547             return err;
548         }
549     }
550     seg = av_mallocz(sizeof(*seg));
551     if (!seg)
552         return AVERROR(ENOMEM);
553     av_strlcpy(seg->file, file, sizeof(seg->file));
554     seg->time = time;
555     seg->duration = duration;
556     seg->start_pos = start_pos;
557     seg->range_length = range_length;
558     seg->index_length = index_length;
559     os->segments[os->nb_segments++] = seg;
560     os->segment_index++;
561     return 0;
562 }
563
564 static void write_styp(AVIOContext *pb)
565 {
566     avio_wb32(pb, 24);
567     ffio_wfourcc(pb, "styp");
568     ffio_wfourcc(pb, "msdh");
569     avio_wb32(pb, 0); /* minor */
570     ffio_wfourcc(pb, "msdh");
571     ffio_wfourcc(pb, "msix");
572 }
573
574 static void find_index_range(AVFormatContext *s, const char *dirname,
575                              const char *filename, int64_t pos,
576                              int *index_length)
577 {
578     char full_path[1024];
579     uint8_t buf[8];
580     URLContext *fd;
581     int ret;
582
583     snprintf(full_path, sizeof(full_path), "%s%s", dirname, filename);
584     ret = ffurl_open(&fd, full_path, AVIO_FLAG_READ, &s->interrupt_callback, NULL);
585     if (ret < 0)
586         return;
587     if (ffurl_seek(fd, pos, SEEK_SET) != pos) {
588         ffurl_close(fd);
589         return;
590     }
591     ret = ffurl_read(fd, buf, 8);
592     ffurl_close(fd);
593     if (ret < 8)
594         return;
595     if (AV_RL32(&buf[4]) != MKTAG('s', 'i', 'd', 'x'))
596         return;
597     *index_length = AV_RB32(&buf[0]);
598 }
599
600 static int dash_flush(AVFormatContext *s, int final, int stream)
601 {
602     DASHContext *c = s->priv_data;
603     int i, ret = 0;
604     int cur_flush_segment_index = 0;
605     if (stream >= 0)
606         cur_flush_segment_index = c->streams[stream].segment_index;
607
608     for (i = 0; i < s->nb_streams; i++) {
609         OutputStream *os = &c->streams[i];
610         char filename[1024] = "", full_path[1024], temp_path[1024];
611         int64_t start_pos = avio_tell(os->ctx->pb);
612         int range_length, index_length = 0;
613
614         if (!os->packets_written)
615             continue;
616
617         // Flush the single stream that got a keyframe right now.
618         // Flush all audio streams as well, in sync with video keyframes,
619         // but not the other video streams.
620         if (stream >= 0 && i != stream) {
621             if (s->streams[i]->codec->codec_type != AVMEDIA_TYPE_AUDIO)
622                 continue;
623             // Make sure we don't flush audio streams multiple times, when
624             // all video streams are flushed one at a time.
625             if (c->has_video && os->segment_index > cur_flush_segment_index)
626                 continue;
627         }
628
629         if (!c->single_file) {
630             snprintf(filename, sizeof(filename), "chunk-stream%d-%05d.m4s", i, os->segment_index);
631             snprintf(full_path, sizeof(full_path), "%s%s", c->dirname, filename);
632             snprintf(temp_path, sizeof(temp_path), "%s.tmp", full_path);
633             ret = ffurl_open(&os->out, temp_path, AVIO_FLAG_WRITE, &s->interrupt_callback, NULL);
634             if (ret < 0)
635                 break;
636             write_styp(os->ctx->pb);
637         }
638         av_write_frame(os->ctx, NULL);
639         avio_flush(os->ctx->pb);
640         os->packets_written = 0;
641
642         range_length = avio_tell(os->ctx->pb) - start_pos;
643         if (c->single_file) {
644             find_index_range(s, c->dirname, os->initfile, start_pos, &index_length);
645         } else {
646             ffurl_close(os->out);
647             os->out = NULL;
648             ret = ff_rename(temp_path, full_path, s);
649             if (ret < 0)
650                 break;
651         }
652         add_segment(os, filename, os->start_dts, os->end_dts - os->start_dts, start_pos, range_length, index_length);
653     }
654
655     if (c->window_size || (final && c->remove_at_exit)) {
656         for (i = 0; i < s->nb_streams; i++) {
657             OutputStream *os = &c->streams[i];
658             int j;
659             int remove = os->nb_segments - c->window_size - c->extra_window_size;
660             if (final && c->remove_at_exit)
661                 remove = os->nb_segments;
662             if (remove > 0) {
663                 for (j = 0; j < remove; j++) {
664                     char filename[1024];
665                     snprintf(filename, sizeof(filename), "%s%s", c->dirname, os->segments[j]->file);
666                     unlink(filename);
667                     av_free(os->segments[j]);
668                 }
669                 os->nb_segments -= remove;
670                 memmove(os->segments, os->segments + remove, os->nb_segments * sizeof(*os->segments));
671             }
672         }
673     }
674
675     if (ret >= 0)
676         ret = write_manifest(s, final);
677     return ret;
678 }
679
680 static int dash_write_packet(AVFormatContext *s, AVPacket *pkt)
681 {
682     DASHContext *c = s->priv_data;
683     AVStream *st = s->streams[pkt->stream_index];
684     OutputStream *os = &c->streams[pkt->stream_index];
685     int64_t seg_end_duration = (os->segment_index) * (int64_t) c->min_seg_duration;
686     int ret;
687
688     // If forcing the stream to start at 0, the mp4 muxer will set the start
689     // timestamps to 0. Do the same here, to avoid mismatches in duration/timestamps.
690     if (os->first_dts == AV_NOPTS_VALUE &&
691         s->avoid_negative_ts == AVFMT_AVOID_NEG_TS_MAKE_ZERO) {
692         pkt->pts -= pkt->dts;
693         pkt->dts  = 0;
694     }
695
696     if (os->first_dts == AV_NOPTS_VALUE)
697         os->first_dts = pkt->dts;
698
699     if ((!c->has_video || st->codec->codec_type == AVMEDIA_TYPE_VIDEO) &&
700         pkt->flags & AV_PKT_FLAG_KEY && os->packets_written &&
701         av_compare_ts(pkt->dts - os->first_dts, st->time_base,
702                       seg_end_duration, AV_TIME_BASE_Q) >= 0) {
703         int64_t prev_duration = c->last_duration;
704
705         c->last_duration = av_rescale_q(pkt->dts - os->start_dts,
706                                         st->time_base,
707                                         AV_TIME_BASE_Q);
708         c->total_duration = av_rescale_q(pkt->dts - os->first_dts,
709                                          st->time_base,
710                                          AV_TIME_BASE_Q);
711
712         if ((!c->use_timeline || !c->use_template) && prev_duration) {
713             if (c->last_duration < prev_duration*9/10 ||
714                 c->last_duration > prev_duration*11/10) {
715                 av_log(s, AV_LOG_WARNING,
716                        "Segment durations differ too much, enable use_timeline "
717                        "and use_template, or keep a stricter keyframe interval\n");
718             }
719         }
720
721         if ((ret = dash_flush(s, 0, pkt->stream_index)) < 0)
722             return ret;
723     }
724
725     if (!os->packets_written)
726         os->start_dts = pkt->dts;
727     os->end_dts = pkt->dts + pkt->duration;
728     os->packets_written++;
729     return ff_write_chained(os->ctx, 0, pkt, s, 0);
730 }
731
732 static int dash_write_trailer(AVFormatContext *s)
733 {
734     DASHContext *c = s->priv_data;
735
736     if (s->nb_streams > 0) {
737         OutputStream *os = &c->streams[0];
738         // If no segments have been written so far, try to do a crude
739         // guess of the segment duration
740         if (!c->last_duration)
741             c->last_duration = av_rescale_q(os->end_dts - os->start_dts,
742                                             s->streams[0]->time_base,
743                                             AV_TIME_BASE_Q);
744         c->total_duration = av_rescale_q(os->end_dts - os->first_dts,
745                                          s->streams[0]->time_base,
746                                          AV_TIME_BASE_Q);
747     }
748     dash_flush(s, 1, -1);
749
750     if (c->remove_at_exit) {
751         char filename[1024];
752         int i;
753         for (i = 0; i < s->nb_streams; i++) {
754             OutputStream *os = &c->streams[i];
755             snprintf(filename, sizeof(filename), "%s%s", c->dirname, os->initfile);
756             unlink(filename);
757         }
758         unlink(s->filename);
759     }
760
761     dash_free(s);
762     return 0;
763 }
764
765 #define OFFSET(x) offsetof(DASHContext, x)
766 #define E AV_OPT_FLAG_ENCODING_PARAM
767 static const AVOption options[] = {
768     { "window_size", "number of segments kept in the manifest", OFFSET(window_size), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, E },
769     { "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 },
770     { "min_seg_duration", "minimum segment duration (in microseconds)", OFFSET(min_seg_duration), AV_OPT_TYPE_INT64, { .i64 = 5000000 }, 0, INT_MAX, E },
771     { "remove_at_exit", "remove all segments when finished", OFFSET(remove_at_exit), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 1, E },
772     { "use_template", "Use SegmentTemplate instead of SegmentList", OFFSET(use_template), AV_OPT_TYPE_INT, { .i64 = 1 }, 0, 1, E },
773     { "use_timeline", "Use SegmentTimeline in SegmentTemplate", OFFSET(use_timeline), AV_OPT_TYPE_INT, { .i64 = 1 }, 0, 1, E },
774     { "single_file", "Store all segments in one file, accessed using byte ranges", OFFSET(single_file), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 1, E },
775     { NULL },
776 };
777
778 static const AVClass dash_class = {
779     .class_name = "dash muxer",
780     .item_name  = av_default_item_name,
781     .option     = options,
782     .version    = LIBAVUTIL_VERSION_INT,
783 };
784
785 AVOutputFormat ff_dash_muxer = {
786     .name           = "dash",
787     .long_name      = NULL_IF_CONFIG_SMALL("DASH Muxer"),
788     .priv_data_size = sizeof(DASHContext),
789     .audio_codec    = AV_CODEC_ID_AAC,
790     .video_codec    = AV_CODEC_ID_H264,
791     .flags          = AVFMT_GLOBALHEADER | AVFMT_NOFILE | AVFMT_TS_NEGATIVE,
792     .write_header   = dash_write_header,
793     .write_packet   = dash_write_packet,
794     .write_trailer  = dash_write_trailer,
795     .codec_tag      = (const AVCodecTag* const []){ ff_mp4_obj_type, 0 },
796     .priv_class     = &dash_class,
797 };