2 * Apple HTTP Live Streaming demuxer
3 * Copyright (c) 2010 Martin Storsjo
4 * Copyright (c) 2013 Anssi Hannula
6 * This file is part of FFmpeg.
8 * FFmpeg is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
11 * version 2.1 of the License, or (at your option) any later version.
13 * FFmpeg is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Lesser General Public License for more details.
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with FFmpeg; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
25 * Apple HTTP Live Streaming demuxer
26 * http://tools.ietf.org/html/draft-pantos-http-live-streaming
29 #include "libavformat/http.h"
30 #include "libavutil/avstring.h"
31 #include "libavutil/avassert.h"
32 #include "libavutil/intreadwrite.h"
33 #include "libavutil/mathematics.h"
34 #include "libavutil/opt.h"
35 #include "libavutil/dict.h"
36 #include "libavutil/time.h"
39 #include "avio_internal.h"
42 #define INITIAL_BUFFER_SIZE 32768
44 #define MAX_FIELD_LEN 64
45 #define MAX_CHARACTERISTICS_LEN 512
47 #define MPEG_TIME_BASE 90000
48 #define MPEG_TIME_BASE_Q (AVRational){1, MPEG_TIME_BASE}
51 * An apple http stream consists of a playlist with media segment files,
52 * played sequentially. There may be several playlists with the same
53 * video content, in different bandwidth variants, that are played in
54 * parallel (preferably only one bandwidth variant at a time). In this case,
55 * the user supplied the url to a main playlist that only lists the variant
58 * If the main playlist doesn't point at any variants, we still create
59 * one anonymous toplevel variant for this, to maintain the structure.
74 enum KeyType key_type;
76 /* associated Media Initialization Section, treated as a segment */
77 struct segment *init_section;
89 * Each playlist has its own demuxer. If it currently is active,
90 * it has an open AVIOContext too, and potentially an AVPacket
91 * containing the next packet from this stream.
94 char url[MAX_URL_SIZE];
99 AVIOContext *input_next;
100 int input_next_requested;
101 AVFormatContext *parent;
103 AVFormatContext *ctx;
105 int has_noheader_flag;
107 /* main demuxer streams associated with this playlist
108 * indexed by the subdemuxer stream indexes */
109 AVStream **main_streams;
113 enum PlaylistType type;
114 int64_t target_duration;
117 struct segment **segments;
120 int64_t cur_seg_offset;
121 int64_t last_load_time;
123 /* Currently active Media Initialization Section */
124 struct segment *cur_init_section;
125 uint8_t *init_sec_buf;
126 unsigned int init_sec_buf_size;
127 unsigned int init_sec_data_len;
128 unsigned int init_sec_buf_read_offset;
130 char key_url[MAX_URL_SIZE];
133 /* ID3 timestamp handling (elementary audio streams have ID3 timestamps
134 * (and possibly other ID3 tags) in the beginning of each segment) */
135 int is_id3_timestamped; /* -1: not yet known */
136 int64_t id3_mpegts_timestamp; /* in mpegts tb */
137 int64_t id3_offset; /* in stream original tb */
138 uint8_t* id3_buf; /* temp buffer for id3 parsing */
139 unsigned int id3_buf_size;
140 AVDictionary *id3_initial; /* data from first id3 tag */
141 int id3_found; /* ID3 tag found at some point */
142 int id3_changed; /* ID3 tag data has changed at some point */
143 ID3v2ExtraMeta *id3_deferred_extra; /* stored here until subdemuxer is opened */
145 int64_t seek_timestamp;
147 int seek_stream_index; /* into subdemuxer stream array */
149 /* Renditions associated with this playlist, if any.
150 * Alternative rendition playlists have a single rendition associated
151 * with them, and variant main Media Playlists may have
152 * multiple (playlist-less) renditions associated with them. */
154 struct rendition **renditions;
156 /* Media Initialization Sections (EXT-X-MAP) associated with this
157 * playlist, if any. */
159 struct segment **init_sections;
163 * Renditions are e.g. alternative subtitle or audio streams.
164 * The rendition may either be an external playlist or it may be
165 * contained in the main Media Playlist of the variant (in which case
169 enum AVMediaType type;
170 struct playlist *playlist;
171 char group_id[MAX_FIELD_LEN];
172 char language[MAX_FIELD_LEN];
173 char name[MAX_FIELD_LEN];
180 /* every variant contains at least the main Media Playlist in index 0 */
182 struct playlist **playlists;
184 char audio_group[MAX_FIELD_LEN];
185 char video_group[MAX_FIELD_LEN];
186 char subtitles_group[MAX_FIELD_LEN];
189 typedef struct HLSContext {
191 AVFormatContext *ctx;
193 struct variant **variants;
195 struct playlist **playlists;
197 struct rendition **renditions;
200 int live_start_index;
202 int64_t first_timestamp;
203 int64_t cur_timestamp;
204 AVIOInterruptCB *interrupt_callback;
205 AVDictionary *avio_opts;
206 int strict_std_compliance;
207 char *allowed_extensions;
211 AVIOContext *playlist_pb;
214 static void free_segment_dynarray(struct segment **segments, int n_segments)
217 for (i = 0; i < n_segments; i++) {
218 av_freep(&segments[i]->key);
219 av_freep(&segments[i]->url);
220 av_freep(&segments[i]);
224 static void free_segment_list(struct playlist *pls)
226 free_segment_dynarray(pls->segments, pls->n_segments);
227 av_freep(&pls->segments);
231 static void free_init_section_list(struct playlist *pls)
234 for (i = 0; i < pls->n_init_sections; i++) {
235 av_freep(&pls->init_sections[i]->url);
236 av_freep(&pls->init_sections[i]);
238 av_freep(&pls->init_sections);
239 pls->n_init_sections = 0;
242 static void free_playlist_list(HLSContext *c)
245 for (i = 0; i < c->n_playlists; i++) {
246 struct playlist *pls = c->playlists[i];
247 free_segment_list(pls);
248 free_init_section_list(pls);
249 av_freep(&pls->main_streams);
250 av_freep(&pls->renditions);
251 av_freep(&pls->id3_buf);
252 av_dict_free(&pls->id3_initial);
253 ff_id3v2_free_extra_meta(&pls->id3_deferred_extra);
254 av_freep(&pls->init_sec_buf);
255 av_packet_unref(&pls->pkt);
256 av_freep(&pls->pb.buffer);
258 ff_format_io_close(c->ctx, &pls->input);
259 pls->input_read_done = 0;
261 ff_format_io_close(c->ctx, &pls->input_next);
262 pls->input_next_requested = 0;
265 avformat_close_input(&pls->ctx);
269 av_freep(&c->playlists);
273 static void free_variant_list(HLSContext *c)
276 for (i = 0; i < c->n_variants; i++) {
277 struct variant *var = c->variants[i];
278 av_freep(&var->playlists);
281 av_freep(&c->variants);
285 static void free_rendition_list(HLSContext *c)
288 for (i = 0; i < c->n_renditions; i++)
289 av_freep(&c->renditions[i]);
290 av_freep(&c->renditions);
295 * Used to reset a statically allocated AVPacket to a clean slate,
296 * containing no data.
298 static void reset_packet(AVPacket *pkt)
304 static struct playlist *new_playlist(HLSContext *c, const char *url,
307 struct playlist *pls = av_mallocz(sizeof(struct playlist));
310 reset_packet(&pls->pkt);
311 ff_make_absolute_url(pls->url, sizeof(pls->url), base, url);
312 pls->seek_timestamp = AV_NOPTS_VALUE;
314 pls->is_id3_timestamped = -1;
315 pls->id3_mpegts_timestamp = AV_NOPTS_VALUE;
317 dynarray_add(&c->playlists, &c->n_playlists, pls);
321 struct variant_info {
323 /* variant group ids: */
324 char audio[MAX_FIELD_LEN];
325 char video[MAX_FIELD_LEN];
326 char subtitles[MAX_FIELD_LEN];
329 static struct variant *new_variant(HLSContext *c, struct variant_info *info,
330 const char *url, const char *base)
333 struct playlist *pls;
335 pls = new_playlist(c, url, base);
339 var = av_mallocz(sizeof(struct variant));
344 var->bandwidth = atoi(info->bandwidth);
345 strcpy(var->audio_group, info->audio);
346 strcpy(var->video_group, info->video);
347 strcpy(var->subtitles_group, info->subtitles);
350 dynarray_add(&c->variants, &c->n_variants, var);
351 dynarray_add(&var->playlists, &var->n_playlists, pls);
355 static void handle_variant_args(struct variant_info *info, const char *key,
356 int key_len, char **dest, int *dest_len)
358 if (!strncmp(key, "BANDWIDTH=", key_len)) {
359 *dest = info->bandwidth;
360 *dest_len = sizeof(info->bandwidth);
361 } else if (!strncmp(key, "AUDIO=", key_len)) {
363 *dest_len = sizeof(info->audio);
364 } else if (!strncmp(key, "VIDEO=", key_len)) {
366 *dest_len = sizeof(info->video);
367 } else if (!strncmp(key, "SUBTITLES=", key_len)) {
368 *dest = info->subtitles;
369 *dest_len = sizeof(info->subtitles);
374 char uri[MAX_URL_SIZE];
379 static void handle_key_args(struct key_info *info, const char *key,
380 int key_len, char **dest, int *dest_len)
382 if (!strncmp(key, "METHOD=", key_len)) {
383 *dest = info->method;
384 *dest_len = sizeof(info->method);
385 } else if (!strncmp(key, "URI=", key_len)) {
387 *dest_len = sizeof(info->uri);
388 } else if (!strncmp(key, "IV=", key_len)) {
390 *dest_len = sizeof(info->iv);
394 struct init_section_info {
395 char uri[MAX_URL_SIZE];
399 static struct segment *new_init_section(struct playlist *pls,
400 struct init_section_info *info,
401 const char *url_base)
405 char tmp_str[MAX_URL_SIZE];
410 sec = av_mallocz(sizeof(*sec));
414 ff_make_absolute_url(tmp_str, sizeof(tmp_str), url_base, info->uri);
415 sec->url = av_strdup(tmp_str);
421 if (info->byterange[0]) {
422 sec->size = strtoll(info->byterange, NULL, 10);
423 ptr = strchr(info->byterange, '@');
425 sec->url_offset = strtoll(ptr+1, NULL, 10);
427 /* the entire file is the init section */
431 dynarray_add(&pls->init_sections, &pls->n_init_sections, sec);
436 static void handle_init_section_args(struct init_section_info *info, const char *key,
437 int key_len, char **dest, int *dest_len)
439 if (!strncmp(key, "URI=", key_len)) {
441 *dest_len = sizeof(info->uri);
442 } else if (!strncmp(key, "BYTERANGE=", key_len)) {
443 *dest = info->byterange;
444 *dest_len = sizeof(info->byterange);
448 struct rendition_info {
450 char uri[MAX_URL_SIZE];
451 char group_id[MAX_FIELD_LEN];
452 char language[MAX_FIELD_LEN];
453 char assoc_language[MAX_FIELD_LEN];
454 char name[MAX_FIELD_LEN];
457 char characteristics[MAX_CHARACTERISTICS_LEN];
460 static struct rendition *new_rendition(HLSContext *c, struct rendition_info *info,
461 const char *url_base)
463 struct rendition *rend;
464 enum AVMediaType type = AVMEDIA_TYPE_UNKNOWN;
465 char *characteristic;
469 if (!strcmp(info->type, "AUDIO"))
470 type = AVMEDIA_TYPE_AUDIO;
471 else if (!strcmp(info->type, "VIDEO"))
472 type = AVMEDIA_TYPE_VIDEO;
473 else if (!strcmp(info->type, "SUBTITLES"))
474 type = AVMEDIA_TYPE_SUBTITLE;
475 else if (!strcmp(info->type, "CLOSED-CAPTIONS"))
476 /* CLOSED-CAPTIONS is ignored since we do not support CEA-608 CC in
477 * AVC SEI RBSP anyway */
480 if (type == AVMEDIA_TYPE_UNKNOWN)
483 /* URI is mandatory for subtitles as per spec */
484 if (type == AVMEDIA_TYPE_SUBTITLE && !info->uri[0])
487 /* TODO: handle subtitles (each segment has to parsed separately) */
488 if (c->strict_std_compliance > FF_COMPLIANCE_EXPERIMENTAL)
489 if (type == AVMEDIA_TYPE_SUBTITLE)
492 rend = av_mallocz(sizeof(struct rendition));
496 dynarray_add(&c->renditions, &c->n_renditions, rend);
499 strcpy(rend->group_id, info->group_id);
500 strcpy(rend->language, info->language);
501 strcpy(rend->name, info->name);
503 /* add the playlist if this is an external rendition */
505 rend->playlist = new_playlist(c, info->uri, url_base);
507 dynarray_add(&rend->playlist->renditions,
508 &rend->playlist->n_renditions, rend);
511 if (info->assoc_language[0]) {
512 int langlen = strlen(rend->language);
513 if (langlen < sizeof(rend->language) - 3) {
514 rend->language[langlen] = ',';
515 strncpy(rend->language + langlen + 1, info->assoc_language,
516 sizeof(rend->language) - langlen - 2);
520 if (!strcmp(info->defaultr, "YES"))
521 rend->disposition |= AV_DISPOSITION_DEFAULT;
522 if (!strcmp(info->forced, "YES"))
523 rend->disposition |= AV_DISPOSITION_FORCED;
525 chr_ptr = info->characteristics;
526 while ((characteristic = av_strtok(chr_ptr, ",", &saveptr))) {
527 if (!strcmp(characteristic, "public.accessibility.describes-music-and-sound"))
528 rend->disposition |= AV_DISPOSITION_HEARING_IMPAIRED;
529 else if (!strcmp(characteristic, "public.accessibility.describes-video"))
530 rend->disposition |= AV_DISPOSITION_VISUAL_IMPAIRED;
538 static void handle_rendition_args(struct rendition_info *info, const char *key,
539 int key_len, char **dest, int *dest_len)
541 if (!strncmp(key, "TYPE=", key_len)) {
543 *dest_len = sizeof(info->type);
544 } else if (!strncmp(key, "URI=", key_len)) {
546 *dest_len = sizeof(info->uri);
547 } else if (!strncmp(key, "GROUP-ID=", key_len)) {
548 *dest = info->group_id;
549 *dest_len = sizeof(info->group_id);
550 } else if (!strncmp(key, "LANGUAGE=", key_len)) {
551 *dest = info->language;
552 *dest_len = sizeof(info->language);
553 } else if (!strncmp(key, "ASSOC-LANGUAGE=", key_len)) {
554 *dest = info->assoc_language;
555 *dest_len = sizeof(info->assoc_language);
556 } else if (!strncmp(key, "NAME=", key_len)) {
558 *dest_len = sizeof(info->name);
559 } else if (!strncmp(key, "DEFAULT=", key_len)) {
560 *dest = info->defaultr;
561 *dest_len = sizeof(info->defaultr);
562 } else if (!strncmp(key, "FORCED=", key_len)) {
563 *dest = info->forced;
564 *dest_len = sizeof(info->forced);
565 } else if (!strncmp(key, "CHARACTERISTICS=", key_len)) {
566 *dest = info->characteristics;
567 *dest_len = sizeof(info->characteristics);
571 * - AUTOSELECT: client may autoselect based on e.g. system language
572 * - INSTREAM-ID: EIA-608 closed caption number ("CC1".."CC4")
576 /* used by parse_playlist to allocate a new variant+playlist when the
577 * playlist is detected to be a Media Playlist (not Master Playlist)
578 * and we have no parent Master Playlist (parsing of which would have
579 * allocated the variant and playlist already)
580 * *pls == NULL => Master Playlist or parentless Media Playlist
581 * *pls != NULL => parented Media Playlist, playlist+variant allocated */
582 static int ensure_playlist(HLSContext *c, struct playlist **pls, const char *url)
586 if (!new_variant(c, NULL, url, NULL))
587 return AVERROR(ENOMEM);
588 *pls = c->playlists[c->n_playlists - 1];
592 static int open_url_keepalive(AVFormatContext *s, AVIOContext **pb,
595 #if !CONFIG_HTTP_PROTOCOL
596 return AVERROR_PROTOCOL_NOT_FOUND;
599 URLContext *uc = ffio_geturlcontext(*pb);
601 (*pb)->eof_reached = 0;
602 ret = ff_http_do_new_request(uc, url);
604 ff_format_io_close(s, pb);
610 static int open_url(AVFormatContext *s, AVIOContext **pb, const char *url,
611 AVDictionary *opts, AVDictionary *opts2, int *is_http_out)
613 HLSContext *c = s->priv_data;
614 AVDictionary *tmp = NULL;
615 const char *proto_name = NULL;
619 av_dict_copy(&tmp, opts, 0);
620 av_dict_copy(&tmp, opts2, 0);
622 if (av_strstart(url, "crypto", NULL)) {
623 if (url[6] == '+' || url[6] == ':')
624 proto_name = avio_find_protocol_name(url + 7);
628 proto_name = avio_find_protocol_name(url);
631 return AVERROR_INVALIDDATA;
633 // only http(s) & file are allowed
634 if (av_strstart(proto_name, "file", NULL)) {
635 if (strcmp(c->allowed_extensions, "ALL") && !av_match_ext(url, c->allowed_extensions)) {
636 av_log(s, AV_LOG_ERROR,
637 "Filename extension of \'%s\' is not a common multimedia extension, blocked for security reasons.\n"
638 "If you wish to override this adjust allowed_extensions, you can set it to \'ALL\' to allow all\n",
640 return AVERROR_INVALIDDATA;
642 } else if (av_strstart(proto_name, "http", NULL)) {
645 return AVERROR_INVALIDDATA;
647 if (!strncmp(proto_name, url, strlen(proto_name)) && url[strlen(proto_name)] == ':')
649 else if (av_strstart(url, "crypto", NULL) && !strncmp(proto_name, url + 7, strlen(proto_name)) && url[7 + strlen(proto_name)] == ':')
651 else if (strcmp(proto_name, "file") || !strncmp(url, "file,", 5))
652 return AVERROR_INVALIDDATA;
654 if (is_http && c->http_persistent && *pb) {
655 ret = open_url_keepalive(c->ctx, pb, url);
656 if (ret == AVERROR_EXIT) {
658 } else if (ret < 0) {
659 if (ret != AVERROR_EOF)
660 av_log(s, AV_LOG_WARNING,
661 "keepalive request failed for '%s', retrying with new connection: %s\n",
662 url, av_err2str(ret));
663 ret = s->io_open(s, pb, url, AVIO_FLAG_READ, &tmp);
666 ret = s->io_open(s, pb, url, AVIO_FLAG_READ, &tmp);
669 // update cookies on http response with setcookies.
670 char *new_cookies = NULL;
672 if (!(s->flags & AVFMT_FLAG_CUSTOM_IO))
673 av_opt_get(*pb, "cookies", AV_OPT_SEARCH_CHILDREN, (uint8_t**)&new_cookies);
676 av_dict_set(&opts, "cookies", new_cookies, AV_DICT_DONT_STRDUP_VAL);
682 *is_http_out = is_http;
687 static int parse_playlist(HLSContext *c, const char *url,
688 struct playlist *pls, AVIOContext *in)
690 int ret = 0, is_segment = 0, is_variant = 0;
691 int64_t duration = 0;
692 enum KeyType key_type = KEY_NONE;
695 char key[MAX_URL_SIZE] = "";
696 char line[MAX_URL_SIZE];
699 int64_t seg_offset = 0;
700 int64_t seg_size = -1;
701 uint8_t *new_url = NULL;
702 struct variant_info variant_info;
703 char tmp_str[MAX_URL_SIZE];
704 struct segment *cur_init_section = NULL;
705 int is_http = av_strstart(url, "http", NULL);
706 struct segment **prev_segments = NULL;
707 int prev_n_segments = 0;
708 int prev_start_seq_no = -1;
710 if (is_http && !in && c->http_persistent && c->playlist_pb) {
712 ret = open_url_keepalive(c->ctx, &c->playlist_pb, url);
713 if (ret == AVERROR_EXIT) {
715 } else if (ret < 0) {
716 if (ret != AVERROR_EOF)
717 av_log(c->ctx, AV_LOG_WARNING,
718 "keepalive request failed for '%s', retrying with new connection: %s\n",
719 url, av_err2str(ret));
725 AVDictionary *opts = NULL;
726 av_dict_copy(&opts, c->avio_opts, 0);
728 if (c->http_persistent)
729 av_dict_set(&opts, "multiple_requests", "1", 0);
731 ret = c->ctx->io_open(c->ctx, &in, url, AVIO_FLAG_READ, &opts);
736 if (is_http && c->http_persistent)
742 if (av_opt_get(in, "location", AV_OPT_SEARCH_CHILDREN, &new_url) >= 0)
745 ff_get_chomp_line(in, line, sizeof(line));
746 if (strcmp(line, "#EXTM3U")) {
747 ret = AVERROR_INVALIDDATA;
752 prev_start_seq_no = pls->start_seq_no;
753 prev_segments = pls->segments;
754 prev_n_segments = pls->n_segments;
755 pls->segments = NULL;
759 pls->type = PLS_TYPE_UNSPECIFIED;
761 while (!avio_feof(in)) {
762 ff_get_chomp_line(in, line, sizeof(line));
763 if (av_strstart(line, "#EXT-X-STREAM-INF:", &ptr)) {
765 memset(&variant_info, 0, sizeof(variant_info));
766 ff_parse_key_value(ptr, (ff_parse_key_val_cb) handle_variant_args,
768 } else if (av_strstart(line, "#EXT-X-KEY:", &ptr)) {
769 struct key_info info = {{0}};
770 ff_parse_key_value(ptr, (ff_parse_key_val_cb) handle_key_args,
774 if (!strcmp(info.method, "AES-128"))
775 key_type = KEY_AES_128;
776 if (!strcmp(info.method, "SAMPLE-AES"))
777 key_type = KEY_SAMPLE_AES;
778 if (!strncmp(info.iv, "0x", 2) || !strncmp(info.iv, "0X", 2)) {
779 ff_hex_to_data(iv, info.iv + 2);
782 av_strlcpy(key, info.uri, sizeof(key));
783 } else if (av_strstart(line, "#EXT-X-MEDIA:", &ptr)) {
784 struct rendition_info info = {{0}};
785 ff_parse_key_value(ptr, (ff_parse_key_val_cb) handle_rendition_args,
787 new_rendition(c, &info, url);
788 } else if (av_strstart(line, "#EXT-X-TARGETDURATION:", &ptr)) {
789 ret = ensure_playlist(c, &pls, url);
792 pls->target_duration = strtoll(ptr, NULL, 10) * AV_TIME_BASE;
793 } else if (av_strstart(line, "#EXT-X-MEDIA-SEQUENCE:", &ptr)) {
794 ret = ensure_playlist(c, &pls, url);
797 pls->start_seq_no = atoi(ptr);
798 } else if (av_strstart(line, "#EXT-X-PLAYLIST-TYPE:", &ptr)) {
799 ret = ensure_playlist(c, &pls, url);
802 if (!strcmp(ptr, "EVENT"))
803 pls->type = PLS_TYPE_EVENT;
804 else if (!strcmp(ptr, "VOD"))
805 pls->type = PLS_TYPE_VOD;
806 } else if (av_strstart(line, "#EXT-X-MAP:", &ptr)) {
807 struct init_section_info info = {{0}};
808 ret = ensure_playlist(c, &pls, url);
811 ff_parse_key_value(ptr, (ff_parse_key_val_cb) handle_init_section_args,
813 cur_init_section = new_init_section(pls, &info, url);
814 } else if (av_strstart(line, "#EXT-X-ENDLIST", &ptr)) {
817 } else if (av_strstart(line, "#EXTINF:", &ptr)) {
819 duration = atof(ptr) * AV_TIME_BASE;
820 } else if (av_strstart(line, "#EXT-X-BYTERANGE:", &ptr)) {
821 seg_size = strtoll(ptr, NULL, 10);
822 ptr = strchr(ptr, '@');
824 seg_offset = strtoll(ptr+1, NULL, 10);
825 } else if (av_strstart(line, "#", NULL)) {
827 } else if (line[0]) {
829 if (!new_variant(c, &variant_info, line, url)) {
830 ret = AVERROR(ENOMEM);
838 if (!new_variant(c, 0, url, NULL)) {
839 ret = AVERROR(ENOMEM);
842 pls = c->playlists[c->n_playlists - 1];
844 seg = av_malloc(sizeof(struct segment));
846 ret = AVERROR(ENOMEM);
849 seg->duration = duration;
850 seg->key_type = key_type;
852 memcpy(seg->iv, iv, sizeof(iv));
854 int seq = pls->start_seq_no + pls->n_segments;
855 memset(seg->iv, 0, sizeof(seg->iv));
856 AV_WB32(seg->iv + 12, seq);
859 if (key_type != KEY_NONE) {
860 ff_make_absolute_url(tmp_str, sizeof(tmp_str), url, key);
861 seg->key = av_strdup(tmp_str);
864 ret = AVERROR(ENOMEM);
871 ff_make_absolute_url(tmp_str, sizeof(tmp_str), url, line);
872 seg->url = av_strdup(tmp_str);
876 ret = AVERROR(ENOMEM);
880 dynarray_add(&pls->segments, &pls->n_segments, seg);
883 seg->size = seg_size;
885 seg->url_offset = seg_offset;
886 seg_offset += seg_size;
893 seg->init_section = cur_init_section;
898 if (pls->start_seq_no > prev_start_seq_no && c->first_timestamp != AV_NOPTS_VALUE) {
899 int64_t prev_timestamp = c->first_timestamp;
900 int i, diff = pls->start_seq_no - prev_start_seq_no;
901 for (i = 0; i < prev_n_segments && i < diff; i++) {
902 c->first_timestamp += prev_segments[i]->duration;
904 av_log(c->ctx, AV_LOG_DEBUG, "Media sequence change (%d -> %d)"
905 " reflected in first_timestamp: %"PRId64" -> %"PRId64"\n",
906 prev_start_seq_no, pls->start_seq_no,
907 prev_timestamp, c->first_timestamp);
908 } else if (pls->start_seq_no < prev_start_seq_no) {
909 av_log(c->ctx, AV_LOG_WARNING, "Media sequence changed unexpectedly: %d -> %d\n",
910 prev_start_seq_no, pls->start_seq_no);
912 free_segment_dynarray(prev_segments, prev_n_segments);
915 pls->last_load_time = av_gettime_relative();
920 ff_format_io_close(c->ctx, &in);
921 c->ctx->ctx_flags = c->ctx->ctx_flags & ~(unsigned)AVFMTCTX_UNSEEKABLE;
922 if (!c->n_variants || !c->variants[0]->n_playlists ||
923 !(c->variants[0]->playlists[0]->finished ||
924 c->variants[0]->playlists[0]->type == PLS_TYPE_EVENT))
925 c->ctx->ctx_flags |= AVFMTCTX_UNSEEKABLE;
929 static struct segment *current_segment(struct playlist *pls)
931 return pls->segments[pls->cur_seq_no - pls->start_seq_no];
934 static struct segment *next_segment(struct playlist *pls)
936 int n = pls->cur_seq_no - pls->start_seq_no + 1;
937 if (n >= pls->n_segments)
939 return pls->segments[n];
942 static int read_from_url(struct playlist *pls, struct segment *seg,
943 uint8_t *buf, int buf_size)
947 /* limit read if the segment was only a part of a file */
949 buf_size = FFMIN(buf_size, seg->size - pls->cur_seg_offset);
951 ret = avio_read(pls->input, buf, buf_size);
953 pls->cur_seg_offset += ret;
958 /* Parse the raw ID3 data and pass contents to caller */
959 static void parse_id3(AVFormatContext *s, AVIOContext *pb,
960 AVDictionary **metadata, int64_t *dts,
961 ID3v2ExtraMetaAPIC **apic, ID3v2ExtraMeta **extra_meta)
963 static const char id3_priv_owner_ts[] = "com.apple.streaming.transportStreamTimestamp";
964 ID3v2ExtraMeta *meta;
966 ff_id3v2_read_dict(pb, metadata, ID3v2_DEFAULT_MAGIC, extra_meta);
967 for (meta = *extra_meta; meta; meta = meta->next) {
968 if (!strcmp(meta->tag, "PRIV")) {
969 ID3v2ExtraMetaPRIV *priv = meta->data;
970 if (priv->datasize == 8 && !strcmp(priv->owner, id3_priv_owner_ts)) {
971 /* 33-bit MPEG timestamp */
972 int64_t ts = AV_RB64(priv->data);
973 av_log(s, AV_LOG_DEBUG, "HLS ID3 audio timestamp %"PRId64"\n", ts);
974 if ((ts & ~((1ULL << 33) - 1)) == 0)
977 av_log(s, AV_LOG_ERROR, "Invalid HLS ID3 audio timestamp %"PRId64"\n", ts);
979 } else if (!strcmp(meta->tag, "APIC") && apic)
984 /* Check if the ID3 metadata contents have changed */
985 static int id3_has_changed_values(struct playlist *pls, AVDictionary *metadata,
986 ID3v2ExtraMetaAPIC *apic)
988 AVDictionaryEntry *entry = NULL;
989 AVDictionaryEntry *oldentry;
990 /* check that no keys have changed values */
991 while ((entry = av_dict_get(metadata, "", entry, AV_DICT_IGNORE_SUFFIX))) {
992 oldentry = av_dict_get(pls->id3_initial, entry->key, NULL, AV_DICT_MATCH_CASE);
993 if (!oldentry || strcmp(oldentry->value, entry->value) != 0)
997 /* check if apic appeared */
998 if (apic && (pls->ctx->nb_streams != 2 || !pls->ctx->streams[1]->attached_pic.data))
1002 int size = pls->ctx->streams[1]->attached_pic.size;
1003 if (size != apic->buf->size - AV_INPUT_BUFFER_PADDING_SIZE)
1006 if (memcmp(apic->buf->data, pls->ctx->streams[1]->attached_pic.data, size) != 0)
1013 /* Parse ID3 data and handle the found data */
1014 static void handle_id3(AVIOContext *pb, struct playlist *pls)
1016 AVDictionary *metadata = NULL;
1017 ID3v2ExtraMetaAPIC *apic = NULL;
1018 ID3v2ExtraMeta *extra_meta = NULL;
1019 int64_t timestamp = AV_NOPTS_VALUE;
1021 parse_id3(pls->ctx, pb, &metadata, ×tamp, &apic, &extra_meta);
1023 if (timestamp != AV_NOPTS_VALUE) {
1024 pls->id3_mpegts_timestamp = timestamp;
1025 pls->id3_offset = 0;
1028 if (!pls->id3_found) {
1029 /* initial ID3 tags */
1030 av_assert0(!pls->id3_deferred_extra);
1033 /* get picture attachment and set text metadata */
1034 if (pls->ctx->nb_streams)
1035 ff_id3v2_parse_apic(pls->ctx, &extra_meta);
1037 /* demuxer not yet opened, defer picture attachment */
1038 pls->id3_deferred_extra = extra_meta;
1040 ff_id3v2_parse_priv_dict(&metadata, &extra_meta);
1041 av_dict_copy(&pls->ctx->metadata, metadata, 0);
1042 pls->id3_initial = metadata;
1045 if (!pls->id3_changed && id3_has_changed_values(pls, metadata, apic)) {
1046 avpriv_report_missing_feature(pls->ctx, "Changing ID3 metadata in HLS audio elementary stream");
1047 pls->id3_changed = 1;
1049 av_dict_free(&metadata);
1052 if (!pls->id3_deferred_extra)
1053 ff_id3v2_free_extra_meta(&extra_meta);
1056 static void intercept_id3(struct playlist *pls, uint8_t *buf,
1057 int buf_size, int *len)
1059 /* intercept id3 tags, we do not want to pass them to the raw
1060 * demuxer on all segment switches */
1062 int id3_buf_pos = 0;
1064 struct segment *seg = current_segment(pls);
1066 /* gather all the id3 tags */
1068 /* see if we can retrieve enough data for ID3 header */
1069 if (*len < ID3v2_HEADER_SIZE && buf_size >= ID3v2_HEADER_SIZE) {
1070 bytes = read_from_url(pls, seg, buf + *len, ID3v2_HEADER_SIZE - *len);
1073 if (bytes == ID3v2_HEADER_SIZE - *len)
1074 /* no EOF yet, so fill the caller buffer again after
1075 * we have stripped the ID3 tags */
1080 } else if (*len <= 0) {
1087 if (*len < ID3v2_HEADER_SIZE)
1090 if (ff_id3v2_match(buf, ID3v2_DEFAULT_MAGIC)) {
1091 int64_t maxsize = seg->size >= 0 ? seg->size : 1024*1024;
1092 int taglen = ff_id3v2_tag_len(buf);
1093 int tag_got_bytes = FFMIN(taglen, *len);
1094 int remaining = taglen - tag_got_bytes;
1096 if (taglen > maxsize) {
1097 av_log(pls->ctx, AV_LOG_ERROR, "Too large HLS ID3 tag (%d > %"PRId64" bytes)\n",
1103 * Copy the id3 tag to our temporary id3 buffer.
1104 * We could read a small id3 tag directly without memcpy, but
1105 * we would still need to copy the large tags, and handling
1106 * both of those cases together with the possibility for multiple
1107 * tags would make the handling a bit complex.
1109 pls->id3_buf = av_fast_realloc(pls->id3_buf, &pls->id3_buf_size, id3_buf_pos + taglen);
1112 memcpy(pls->id3_buf + id3_buf_pos, buf, tag_got_bytes);
1113 id3_buf_pos += tag_got_bytes;
1115 /* strip the intercepted bytes */
1116 *len -= tag_got_bytes;
1117 memmove(buf, buf + tag_got_bytes, *len);
1118 av_log(pls->ctx, AV_LOG_DEBUG, "Stripped %d HLS ID3 bytes\n", tag_got_bytes);
1120 if (remaining > 0) {
1121 /* read the rest of the tag in */
1122 if (read_from_url(pls, seg, pls->id3_buf + id3_buf_pos, remaining) != remaining)
1124 id3_buf_pos += remaining;
1125 av_log(pls->ctx, AV_LOG_DEBUG, "Stripped additional %d HLS ID3 bytes\n", remaining);
1129 /* no more ID3 tags */
1134 /* re-fill buffer for the caller unless EOF */
1135 if (*len >= 0 && (fill_buf || *len == 0)) {
1136 bytes = read_from_url(pls, seg, buf + *len, buf_size - *len);
1138 /* ignore error if we already had some data */
1146 /* Now parse all the ID3 tags */
1147 AVIOContext id3ioctx;
1148 ffio_init_context(&id3ioctx, pls->id3_buf, id3_buf_pos, 0, NULL, NULL, NULL, NULL);
1149 handle_id3(&id3ioctx, pls);
1152 if (pls->is_id3_timestamped == -1)
1153 pls->is_id3_timestamped = (pls->id3_mpegts_timestamp != AV_NOPTS_VALUE);
1156 static int open_input(HLSContext *c, struct playlist *pls, struct segment *seg, AVIOContext **in)
1158 AVDictionary *opts = NULL;
1162 if (c->http_persistent)
1163 av_dict_set(&opts, "multiple_requests", "1", 0);
1165 if (seg->size >= 0) {
1166 /* try to restrict the HTTP request to the part we want
1167 * (if this is in fact a HTTP request) */
1168 av_dict_set_int(&opts, "offset", seg->url_offset, 0);
1169 av_dict_set_int(&opts, "end_offset", seg->url_offset + seg->size, 0);
1172 av_log(pls->parent, AV_LOG_VERBOSE, "HLS request for url '%s', offset %"PRId64", playlist %d\n",
1173 seg->url, seg->url_offset, pls->index);
1175 if (seg->key_type == KEY_NONE) {
1176 ret = open_url(pls->parent, in, seg->url, c->avio_opts, opts, &is_http);
1177 } else if (seg->key_type == KEY_AES_128) {
1178 char iv[33], key[33], url[MAX_URL_SIZE];
1179 if (strcmp(seg->key, pls->key_url)) {
1180 AVIOContext *pb = NULL;
1181 if (open_url(pls->parent, &pb, seg->key, c->avio_opts, opts, NULL) == 0) {
1182 ret = avio_read(pb, pls->key, sizeof(pls->key));
1183 if (ret != sizeof(pls->key)) {
1184 av_log(NULL, AV_LOG_ERROR, "Unable to read key file %s\n",
1187 ff_format_io_close(pls->parent, &pb);
1189 av_log(NULL, AV_LOG_ERROR, "Unable to open key file %s\n",
1192 av_strlcpy(pls->key_url, seg->key, sizeof(pls->key_url));
1194 ff_data_to_hex(iv, seg->iv, sizeof(seg->iv), 0);
1195 ff_data_to_hex(key, pls->key, sizeof(pls->key), 0);
1196 iv[32] = key[32] = '\0';
1197 if (strstr(seg->url, "://"))
1198 snprintf(url, sizeof(url), "crypto+%s", seg->url);
1200 snprintf(url, sizeof(url), "crypto:%s", seg->url);
1202 av_dict_set(&opts, "key", key, 0);
1203 av_dict_set(&opts, "iv", iv, 0);
1205 ret = open_url(pls->parent, in, url, c->avio_opts, opts, &is_http);
1210 } else if (seg->key_type == KEY_SAMPLE_AES) {
1211 av_log(pls->parent, AV_LOG_ERROR,
1212 "SAMPLE-AES encryption is not supported yet\n");
1213 ret = AVERROR_PATCHWELCOME;
1216 ret = AVERROR(ENOSYS);
1218 /* Seek to the requested position. If this was a HTTP request, the offset
1219 * should already be where want it to, but this allows e.g. local testing
1220 * without a HTTP server.
1222 * This is not done for HTTP at all as avio_seek() does internal bookkeeping
1223 * of file offset which is out-of-sync with the actual offset when "offset"
1224 * AVOption is used with http protocol, causing the seek to not be a no-op
1225 * as would be expected. Wrong offset received from the server will not be
1226 * noticed without the call, though.
1228 if (ret == 0 && !is_http && seg->key_type == KEY_NONE && seg->url_offset) {
1229 int64_t seekret = avio_seek(*in, seg->url_offset, SEEK_SET);
1231 av_log(pls->parent, AV_LOG_ERROR, "Unable to seek to offset %"PRId64" of HLS segment '%s'\n", seg->url_offset, seg->url);
1233 ff_format_io_close(pls->parent, in);
1238 av_dict_free(&opts);
1239 pls->cur_seg_offset = 0;
1243 static int update_init_section(struct playlist *pls, struct segment *seg)
1245 static const int max_init_section_size = 1024*1024;
1246 HLSContext *c = pls->parent->priv_data;
1251 if (seg->init_section == pls->cur_init_section)
1254 pls->cur_init_section = NULL;
1256 if (!seg->init_section)
1259 ret = open_input(c, pls, seg->init_section, &pls->input);
1261 av_log(pls->parent, AV_LOG_WARNING,
1262 "Failed to open an initialization section in playlist %d\n",
1267 if (seg->init_section->size >= 0)
1268 sec_size = seg->init_section->size;
1269 else if ((urlsize = avio_size(pls->input)) >= 0)
1272 sec_size = max_init_section_size;
1274 av_log(pls->parent, AV_LOG_DEBUG,
1275 "Downloading an initialization section of size %"PRId64"\n",
1278 sec_size = FFMIN(sec_size, max_init_section_size);
1280 av_fast_malloc(&pls->init_sec_buf, &pls->init_sec_buf_size, sec_size);
1282 ret = read_from_url(pls, seg->init_section, pls->init_sec_buf,
1283 pls->init_sec_buf_size);
1284 ff_format_io_close(pls->parent, &pls->input);
1289 pls->cur_init_section = seg->init_section;
1290 pls->init_sec_data_len = ret;
1291 pls->init_sec_buf_read_offset = 0;
1293 /* spec says audio elementary streams do not have media initialization
1294 * sections, so there should be no ID3 timestamps */
1295 pls->is_id3_timestamped = 0;
1300 static int64_t default_reload_interval(struct playlist *pls)
1302 return pls->n_segments > 0 ?
1303 pls->segments[pls->n_segments - 1]->duration :
1304 pls->target_duration;
1307 static int playlist_needed(struct playlist *pls)
1309 AVFormatContext *s = pls->parent;
1311 int stream_needed = 0;
1314 /* If there is no context or streams yet, the playlist is needed */
1315 if (!pls->ctx || !pls->n_main_streams)
1318 /* check if any of the streams in the playlist are needed */
1319 for (i = 0; i < pls->n_main_streams; i++) {
1320 if (pls->main_streams[i]->discard < AVDISCARD_ALL) {
1326 /* If all streams in the playlist were discarded, the playlist is not
1327 * needed (regardless of whether whole programs are discarded or not). */
1331 /* Otherwise, check if all the programs (variants) this playlist is in are
1332 * discarded. Since all streams in the playlist are part of the same programs
1333 * we can just check the programs of the first stream. */
1335 first_st = pls->main_streams[0]->index;
1337 for (i = 0; i < s->nb_programs; i++) {
1338 AVProgram *program = s->programs[i];
1339 if (program->discard < AVDISCARD_ALL) {
1340 for (j = 0; j < program->nb_stream_indexes; j++) {
1341 if (program->stream_index[j] == first_st) {
1342 /* playlist is in an undiscarded program */
1349 /* some streams were not discarded but all the programs were */
1353 static int read_data(void *opaque, uint8_t *buf, int buf_size)
1355 struct playlist *v = opaque;
1356 HLSContext *c = v->parent->priv_data;
1358 int just_opened = 0;
1359 int reload_count = 0;
1360 struct segment *seg;
1366 if (!v->input || (c->http_persistent && v->input_read_done)) {
1367 int64_t reload_interval;
1369 /* Check that the playlist is still needed before opening a new
1371 v->needed = playlist_needed(v);
1374 av_log(v->parent, AV_LOG_INFO, "No longer receiving playlist %d\n",
1379 /* If this is a live stream and the reload interval has elapsed since
1380 * the last playlist reload, reload the playlists now. */
1381 reload_interval = default_reload_interval(v);
1385 if (reload_count > c->max_reload)
1388 av_gettime_relative() - v->last_load_time >= reload_interval) {
1389 if ((ret = parse_playlist(c, v->url, v, NULL)) < 0) {
1390 if (ret != AVERROR_EXIT)
1391 av_log(v->parent, AV_LOG_WARNING, "Failed to reload playlist %d\n",
1395 /* If we need to reload the playlist again below (if
1396 * there's still no more segments), switch to a reload
1397 * interval of half the target duration. */
1398 reload_interval = v->target_duration / 2;
1400 if (v->cur_seq_no < v->start_seq_no) {
1401 av_log(NULL, AV_LOG_WARNING,
1402 "skipping %d segments ahead, expired from playlists\n",
1403 v->start_seq_no - v->cur_seq_no);
1404 v->cur_seq_no = v->start_seq_no;
1406 if (v->cur_seq_no >= v->start_seq_no + v->n_segments) {
1409 while (av_gettime_relative() - v->last_load_time < reload_interval) {
1410 if (ff_check_interrupt(c->interrupt_callback))
1411 return AVERROR_EXIT;
1412 av_usleep(100*1000);
1414 /* Enough time has elapsed since the last reload */
1418 v->input_read_done = 0;
1419 seg = current_segment(v);
1421 /* load/update Media Initialization Section, if any */
1422 ret = update_init_section(v, seg);
1426 if (c->http_multiple == 1 && v->input_next_requested) {
1427 FFSWAP(AVIOContext *, v->input, v->input_next);
1428 v->input_next_requested = 0;
1431 ret = open_input(c, v, seg, &v->input);
1434 if (ff_check_interrupt(c->interrupt_callback))
1435 return AVERROR_EXIT;
1436 av_log(v->parent, AV_LOG_WARNING, "Failed to open segment %d of playlist %d\n",
1445 if (c->http_multiple == -1) {
1446 uint8_t *http_version_opt = NULL;
1447 int r = av_opt_get(v->input, "http_version", AV_OPT_SEARCH_CHILDREN, &http_version_opt);
1449 c->http_multiple = strncmp((const char *)http_version_opt, "1.1", 3) == 0;
1450 av_freep(&http_version_opt);
1454 seg = next_segment(v);
1455 if (c->http_multiple == 1 && !v->input_next_requested &&
1456 seg && seg->key_type == KEY_NONE && av_strstart(seg->url, "http", NULL)) {
1457 ret = open_input(c, v, seg, &v->input_next);
1459 if (ff_check_interrupt(c->interrupt_callback))
1460 return AVERROR_EXIT;
1461 av_log(v->parent, AV_LOG_WARNING, "Failed to open segment %d of playlist %d\n",
1465 v->input_next_requested = 1;
1469 if (v->init_sec_buf_read_offset < v->init_sec_data_len) {
1470 /* Push init section out first before first actual segment */
1471 int copy_size = FFMIN(v->init_sec_data_len - v->init_sec_buf_read_offset, buf_size);
1472 memcpy(buf, v->init_sec_buf, copy_size);
1473 v->init_sec_buf_read_offset += copy_size;
1477 seg = current_segment(v);
1478 ret = read_from_url(v, seg, buf, buf_size);
1480 if (just_opened && v->is_id3_timestamped != 0) {
1481 /* Intercept ID3 tags here, elementary audio streams are required
1482 * to convey timestamps using them in the beginning of each segment. */
1483 intercept_id3(v, buf, buf_size, &ret);
1488 if (c->http_persistent &&
1489 seg->key_type == KEY_NONE && av_strstart(seg->url, "http", NULL)) {
1490 v->input_read_done = 1;
1492 ff_format_io_close(v->parent, &v->input);
1496 c->cur_seq_no = v->cur_seq_no;
1501 static void add_renditions_to_variant(HLSContext *c, struct variant *var,
1502 enum AVMediaType type, const char *group_id)
1506 for (i = 0; i < c->n_renditions; i++) {
1507 struct rendition *rend = c->renditions[i];
1509 if (rend->type == type && !strcmp(rend->group_id, group_id)) {
1512 /* rendition is an external playlist
1513 * => add the playlist to the variant */
1514 dynarray_add(&var->playlists, &var->n_playlists, rend->playlist);
1516 /* rendition is part of the variant main Media Playlist
1517 * => add the rendition to the main Media Playlist */
1518 dynarray_add(&var->playlists[0]->renditions,
1519 &var->playlists[0]->n_renditions,
1525 static void add_metadata_from_renditions(AVFormatContext *s, struct playlist *pls,
1526 enum AVMediaType type)
1531 for (i = 0; i < pls->n_main_streams; i++) {
1532 AVStream *st = pls->main_streams[i];
1534 if (st->codecpar->codec_type != type)
1537 for (; rend_idx < pls->n_renditions; rend_idx++) {
1538 struct rendition *rend = pls->renditions[rend_idx];
1540 if (rend->type != type)
1543 if (rend->language[0])
1544 av_dict_set(&st->metadata, "language", rend->language, 0);
1546 av_dict_set(&st->metadata, "comment", rend->name, 0);
1548 st->disposition |= rend->disposition;
1550 if (rend_idx >=pls->n_renditions)
1555 /* if timestamp was in valid range: returns 1 and sets seq_no
1556 * if not: returns 0 and sets seq_no to closest segment */
1557 static int find_timestamp_in_playlist(HLSContext *c, struct playlist *pls,
1558 int64_t timestamp, int *seq_no)
1561 int64_t pos = c->first_timestamp == AV_NOPTS_VALUE ?
1562 0 : c->first_timestamp;
1564 if (timestamp < pos) {
1565 *seq_no = pls->start_seq_no;
1569 for (i = 0; i < pls->n_segments; i++) {
1570 int64_t diff = pos + pls->segments[i]->duration - timestamp;
1572 *seq_no = pls->start_seq_no + i;
1575 pos += pls->segments[i]->duration;
1578 *seq_no = pls->start_seq_no + pls->n_segments - 1;
1583 static int select_cur_seq_no(HLSContext *c, struct playlist *pls)
1587 if (!pls->finished && !c->first_packet &&
1588 av_gettime_relative() - pls->last_load_time >= default_reload_interval(pls))
1589 /* reload the playlist since it was suspended */
1590 parse_playlist(c, pls->url, pls, NULL);
1592 /* If playback is already in progress (we are just selecting a new
1593 * playlist) and this is a complete file, find the matching segment
1594 * by counting durations. */
1595 if (pls->finished && c->cur_timestamp != AV_NOPTS_VALUE) {
1596 find_timestamp_in_playlist(c, pls, c->cur_timestamp, &seq_no);
1600 if (!pls->finished) {
1601 if (!c->first_packet && /* we are doing a segment selection during playback */
1602 c->cur_seq_no >= pls->start_seq_no &&
1603 c->cur_seq_no < pls->start_seq_no + pls->n_segments)
1604 /* While spec 3.4.3 says that we cannot assume anything about the
1605 * content at the same sequence number on different playlists,
1606 * in practice this seems to work and doing it otherwise would
1607 * require us to download a segment to inspect its timestamps. */
1608 return c->cur_seq_no;
1610 /* If this is a live stream, start live_start_index segments from the
1612 if (c->live_start_index < 0)
1613 return pls->start_seq_no + FFMAX(pls->n_segments + c->live_start_index, 0);
1615 return pls->start_seq_no + FFMIN(c->live_start_index, pls->n_segments - 1);
1618 /* Otherwise just start on the first segment. */
1619 return pls->start_seq_no;
1622 static int save_avio_options(AVFormatContext *s)
1624 HLSContext *c = s->priv_data;
1625 static const char * const opts[] = {
1626 "headers", "http_proxy", "user_agent", "cookies", "referer", "rw_timeout", NULL };
1627 const char * const * opt = opts;
1632 if (av_opt_get(s->pb, *opt, AV_OPT_SEARCH_CHILDREN | AV_OPT_ALLOW_NULL, &buf) >= 0) {
1633 ret = av_dict_set(&c->avio_opts, *opt, buf,
1634 AV_DICT_DONT_STRDUP_VAL);
1644 static int nested_io_open(AVFormatContext *s, AVIOContext **pb, const char *url,
1645 int flags, AVDictionary **opts)
1647 av_log(s, AV_LOG_ERROR,
1648 "A HLS playlist item '%s' referred to an external file '%s'. "
1649 "Opening this file was forbidden for security reasons\n",
1651 return AVERROR(EPERM);
1654 static void add_stream_to_programs(AVFormatContext *s, struct playlist *pls, AVStream *stream)
1656 HLSContext *c = s->priv_data;
1660 for (i = 0; i < c->n_variants; i++) {
1661 struct variant *v = c->variants[i];
1663 for (j = 0; j < v->n_playlists; j++) {
1664 if (v->playlists[j] != pls)
1667 av_program_add_stream_index(s, i, stream->index);
1670 bandwidth = v->bandwidth;
1671 else if (bandwidth != v->bandwidth)
1672 bandwidth = -1; /* stream in multiple variants with different bandwidths */
1677 av_dict_set_int(&stream->metadata, "variant_bitrate", bandwidth, 0);
1680 static int set_stream_info_from_input_stream(AVStream *st, struct playlist *pls, AVStream *ist)
1684 err = avcodec_parameters_copy(st->codecpar, ist->codecpar);
1688 if (pls->is_id3_timestamped) /* custom timestamps via id3 */
1689 avpriv_set_pts_info(st, 33, 1, MPEG_TIME_BASE);
1691 avpriv_set_pts_info(st, ist->pts_wrap_bits, ist->time_base.num, ist->time_base.den);
1693 st->internal->need_context_update = 1;
1698 /* add new subdemuxer streams to our context, if any */
1699 static int update_streams_from_subdemuxer(AVFormatContext *s, struct playlist *pls)
1703 while (pls->n_main_streams < pls->ctx->nb_streams) {
1704 int ist_idx = pls->n_main_streams;
1705 AVStream *st = avformat_new_stream(s, NULL);
1706 AVStream *ist = pls->ctx->streams[ist_idx];
1709 return AVERROR(ENOMEM);
1711 st->id = pls->index;
1712 dynarray_add(&pls->main_streams, &pls->n_main_streams, st);
1714 add_stream_to_programs(s, pls, st);
1716 err = set_stream_info_from_input_stream(st, pls, ist);
1724 static void update_noheader_flag(AVFormatContext *s)
1726 HLSContext *c = s->priv_data;
1727 int flag_needed = 0;
1730 for (i = 0; i < c->n_playlists; i++) {
1731 struct playlist *pls = c->playlists[i];
1733 if (pls->has_noheader_flag) {
1740 s->ctx_flags |= AVFMTCTX_NOHEADER;
1742 s->ctx_flags &= ~AVFMTCTX_NOHEADER;
1745 static int hls_close(AVFormatContext *s)
1747 HLSContext *c = s->priv_data;
1749 free_playlist_list(c);
1750 free_variant_list(c);
1751 free_rendition_list(c);
1753 av_dict_free(&c->avio_opts);
1754 ff_format_io_close(c->ctx, &c->playlist_pb);
1759 static int hls_read_header(AVFormatContext *s)
1761 HLSContext *c = s->priv_data;
1763 int highest_cur_seq_no = 0;
1766 c->interrupt_callback = &s->interrupt_callback;
1767 c->strict_std_compliance = s->strict_std_compliance;
1769 c->first_packet = 1;
1770 c->first_timestamp = AV_NOPTS_VALUE;
1771 c->cur_timestamp = AV_NOPTS_VALUE;
1773 if ((ret = save_avio_options(s)) < 0)
1776 /* Some HLS servers don't like being sent the range header */
1777 av_dict_set(&c->avio_opts, "seekable", "0", 0);
1779 if ((ret = parse_playlist(c, s->url, NULL, s->pb)) < 0)
1782 if (c->n_variants == 0) {
1783 av_log(NULL, AV_LOG_WARNING, "Empty playlist\n");
1787 /* If the playlist only contained playlists (Master Playlist),
1788 * parse each individual playlist. */
1789 if (c->n_playlists > 1 || c->playlists[0]->n_segments == 0) {
1790 for (i = 0; i < c->n_playlists; i++) {
1791 struct playlist *pls = c->playlists[i];
1792 if ((ret = parse_playlist(c, pls->url, pls, NULL)) < 0)
1797 if (c->variants[0]->playlists[0]->n_segments == 0) {
1798 av_log(NULL, AV_LOG_WARNING, "Empty playlist\n");
1803 /* If this isn't a live stream, calculate the total duration of the
1805 if (c->variants[0]->playlists[0]->finished) {
1806 int64_t duration = 0;
1807 for (i = 0; i < c->variants[0]->playlists[0]->n_segments; i++)
1808 duration += c->variants[0]->playlists[0]->segments[i]->duration;
1809 s->duration = duration;
1812 /* Associate renditions with variants */
1813 for (i = 0; i < c->n_variants; i++) {
1814 struct variant *var = c->variants[i];
1816 if (var->audio_group[0])
1817 add_renditions_to_variant(c, var, AVMEDIA_TYPE_AUDIO, var->audio_group);
1818 if (var->video_group[0])
1819 add_renditions_to_variant(c, var, AVMEDIA_TYPE_VIDEO, var->video_group);
1820 if (var->subtitles_group[0])
1821 add_renditions_to_variant(c, var, AVMEDIA_TYPE_SUBTITLE, var->subtitles_group);
1824 /* Create a program for each variant */
1825 for (i = 0; i < c->n_variants; i++) {
1826 struct variant *v = c->variants[i];
1829 program = av_new_program(s, i);
1832 av_dict_set_int(&program->metadata, "variant_bitrate", v->bandwidth, 0);
1835 /* Select the starting segments */
1836 for (i = 0; i < c->n_playlists; i++) {
1837 struct playlist *pls = c->playlists[i];
1839 if (pls->n_segments == 0)
1842 pls->cur_seq_no = select_cur_seq_no(c, pls);
1843 highest_cur_seq_no = FFMAX(highest_cur_seq_no, pls->cur_seq_no);
1846 /* Open the demuxer for each playlist */
1847 for (i = 0; i < c->n_playlists; i++) {
1848 struct playlist *pls = c->playlists[i];
1849 AVInputFormat *in_fmt = NULL;
1851 if (!(pls->ctx = avformat_alloc_context())) {
1852 ret = AVERROR(ENOMEM);
1856 if (pls->n_segments == 0)
1864 * If this is a live stream and this playlist looks like it is one segment
1865 * behind, try to sync it up so that every substream starts at the same
1866 * time position (so e.g. avformat_find_stream_info() will see packets from
1867 * all active streams within the first few seconds). This is not very generic,
1868 * though, as the sequence numbers are technically independent.
1870 if (!pls->finished && pls->cur_seq_no == highest_cur_seq_no - 1 &&
1871 highest_cur_seq_no < pls->start_seq_no + pls->n_segments) {
1872 pls->cur_seq_no = highest_cur_seq_no;
1875 pls->read_buffer = av_malloc(INITIAL_BUFFER_SIZE);
1876 if (!pls->read_buffer){
1877 ret = AVERROR(ENOMEM);
1878 avformat_free_context(pls->ctx);
1882 ffio_init_context(&pls->pb, pls->read_buffer, INITIAL_BUFFER_SIZE, 0, pls,
1883 read_data, NULL, NULL);
1884 pls->pb.seekable = 0;
1885 ret = av_probe_input_buffer(&pls->pb, &in_fmt, pls->segments[0]->url,
1888 /* Free the ctx - it isn't initialized properly at this point,
1889 * so avformat_close_input shouldn't be called. If
1890 * avformat_open_input fails below, it frees and zeros the
1891 * context, so it doesn't need any special treatment like this. */
1892 av_log(s, AV_LOG_ERROR, "Error when loading first segment '%s'\n", pls->segments[0]->url);
1893 avformat_free_context(pls->ctx);
1897 pls->ctx->pb = &pls->pb;
1898 pls->ctx->io_open = nested_io_open;
1899 pls->ctx->flags |= s->flags & ~AVFMT_FLAG_CUSTOM_IO;
1901 if ((ret = ff_copy_whiteblacklists(pls->ctx, s)) < 0)
1904 ret = avformat_open_input(&pls->ctx, pls->segments[0]->url, in_fmt, NULL);
1908 if (pls->id3_deferred_extra && pls->ctx->nb_streams == 1) {
1909 ff_id3v2_parse_apic(pls->ctx, &pls->id3_deferred_extra);
1910 avformat_queue_attached_pictures(pls->ctx);
1911 ff_id3v2_parse_priv(pls->ctx, &pls->id3_deferred_extra);
1912 ff_id3v2_free_extra_meta(&pls->id3_deferred_extra);
1913 pls->id3_deferred_extra = NULL;
1916 if (pls->is_id3_timestamped == -1)
1917 av_log(s, AV_LOG_WARNING, "No expected HTTP requests have been made\n");
1920 * For ID3 timestamped raw audio streams we need to detect the packet
1921 * durations to calculate timestamps in fill_timing_for_id3_timestamped_stream(),
1922 * but for other streams we can rely on our user calling avformat_find_stream_info()
1923 * on us if they want to.
1925 if (pls->is_id3_timestamped) {
1926 ret = avformat_find_stream_info(pls->ctx, NULL);
1931 pls->has_noheader_flag = !!(pls->ctx->ctx_flags & AVFMTCTX_NOHEADER);
1933 /* Create new AVStreams for each stream in this playlist */
1934 ret = update_streams_from_subdemuxer(s, pls);
1939 * Copy any metadata from playlist to main streams, but do not set
1942 if (pls->n_main_streams)
1943 av_dict_copy(&pls->main_streams[0]->metadata, pls->ctx->metadata, 0);
1945 add_metadata_from_renditions(s, pls, AVMEDIA_TYPE_AUDIO);
1946 add_metadata_from_renditions(s, pls, AVMEDIA_TYPE_VIDEO);
1947 add_metadata_from_renditions(s, pls, AVMEDIA_TYPE_SUBTITLE);
1950 update_noheader_flag(s);
1958 static int recheck_discard_flags(AVFormatContext *s, int first)
1960 HLSContext *c = s->priv_data;
1964 /* Check if any new streams are needed */
1965 for (i = 0; i < c->n_playlists; i++) {
1966 struct playlist *pls = c->playlists[i];
1968 cur_needed = playlist_needed(c->playlists[i]);
1970 if (cur_needed && !pls->needed) {
1973 pls->cur_seq_no = select_cur_seq_no(c, pls);
1974 pls->pb.eof_reached = 0;
1975 if (c->cur_timestamp != AV_NOPTS_VALUE) {
1977 pls->seek_timestamp = c->cur_timestamp;
1978 pls->seek_flags = AVSEEK_FLAG_ANY;
1979 pls->seek_stream_index = -1;
1981 av_log(s, AV_LOG_INFO, "Now receiving playlist %d, segment %d\n", i, pls->cur_seq_no);
1982 } else if (first && !cur_needed && pls->needed) {
1984 ff_format_io_close(pls->parent, &pls->input);
1985 pls->input_read_done = 0;
1986 if (pls->input_next)
1987 ff_format_io_close(pls->parent, &pls->input_next);
1988 pls->input_next_requested = 0;
1991 av_log(s, AV_LOG_INFO, "No longer receiving playlist %d\n", i);
1997 static void fill_timing_for_id3_timestamped_stream(struct playlist *pls)
1999 if (pls->id3_offset >= 0) {
2000 pls->pkt.dts = pls->id3_mpegts_timestamp +
2001 av_rescale_q(pls->id3_offset,
2002 pls->ctx->streams[pls->pkt.stream_index]->time_base,
2004 if (pls->pkt.duration)
2005 pls->id3_offset += pls->pkt.duration;
2007 pls->id3_offset = -1;
2009 /* there have been packets with unknown duration
2010 * since the last id3 tag, should not normally happen */
2011 pls->pkt.dts = AV_NOPTS_VALUE;
2014 if (pls->pkt.duration)
2015 pls->pkt.duration = av_rescale_q(pls->pkt.duration,
2016 pls->ctx->streams[pls->pkt.stream_index]->time_base,
2019 pls->pkt.pts = AV_NOPTS_VALUE;
2022 static AVRational get_timebase(struct playlist *pls)
2024 if (pls->is_id3_timestamped)
2025 return MPEG_TIME_BASE_Q;
2027 return pls->ctx->streams[pls->pkt.stream_index]->time_base;
2030 static int compare_ts_with_wrapdetect(int64_t ts_a, struct playlist *pls_a,
2031 int64_t ts_b, struct playlist *pls_b)
2033 int64_t scaled_ts_a = av_rescale_q(ts_a, get_timebase(pls_a), MPEG_TIME_BASE_Q);
2034 int64_t scaled_ts_b = av_rescale_q(ts_b, get_timebase(pls_b), MPEG_TIME_BASE_Q);
2036 return av_compare_mod(scaled_ts_a, scaled_ts_b, 1LL << 33);
2039 static int hls_read_packet(AVFormatContext *s, AVPacket *pkt)
2041 HLSContext *c = s->priv_data;
2042 int ret, i, minplaylist = -1;
2044 recheck_discard_flags(s, c->first_packet);
2045 c->first_packet = 0;
2047 for (i = 0; i < c->n_playlists; i++) {
2048 struct playlist *pls = c->playlists[i];
2049 /* Make sure we've got one buffered packet from each open playlist
2051 if (pls->needed && !pls->pkt.data) {
2055 ret = av_read_frame(pls->ctx, &pls->pkt);
2057 if (!avio_feof(&pls->pb) && ret != AVERROR_EOF)
2059 reset_packet(&pls->pkt);
2062 /* stream_index check prevents matching picture attachments etc. */
2063 if (pls->is_id3_timestamped && pls->pkt.stream_index == 0) {
2064 /* audio elementary streams are id3 timestamped */
2065 fill_timing_for_id3_timestamped_stream(pls);
2068 if (c->first_timestamp == AV_NOPTS_VALUE &&
2069 pls->pkt.dts != AV_NOPTS_VALUE)
2070 c->first_timestamp = av_rescale_q(pls->pkt.dts,
2071 get_timebase(pls), AV_TIME_BASE_Q);
2074 if (pls->seek_timestamp == AV_NOPTS_VALUE)
2077 if (pls->seek_stream_index < 0 ||
2078 pls->seek_stream_index == pls->pkt.stream_index) {
2080 if (pls->pkt.dts == AV_NOPTS_VALUE) {
2081 pls->seek_timestamp = AV_NOPTS_VALUE;
2085 tb = get_timebase(pls);
2086 ts_diff = av_rescale_rnd(pls->pkt.dts, AV_TIME_BASE,
2087 tb.den, AV_ROUND_DOWN) -
2088 pls->seek_timestamp;
2089 if (ts_diff >= 0 && (pls->seek_flags & AVSEEK_FLAG_ANY ||
2090 pls->pkt.flags & AV_PKT_FLAG_KEY)) {
2091 pls->seek_timestamp = AV_NOPTS_VALUE;
2095 av_packet_unref(&pls->pkt);
2096 reset_packet(&pls->pkt);
2099 /* Check if this stream has the packet with the lowest dts */
2100 if (pls->pkt.data) {
2101 struct playlist *minpls = minplaylist < 0 ?
2102 NULL : c->playlists[minplaylist];
2103 if (minplaylist < 0) {
2106 int64_t dts = pls->pkt.dts;
2107 int64_t mindts = minpls->pkt.dts;
2109 if (dts == AV_NOPTS_VALUE ||
2110 (mindts != AV_NOPTS_VALUE && compare_ts_with_wrapdetect(dts, pls, mindts, minpls) < 0))
2116 /* If we got a packet, return it */
2117 if (minplaylist >= 0) {
2118 struct playlist *pls = c->playlists[minplaylist];
2122 ret = update_streams_from_subdemuxer(s, pls);
2124 av_packet_unref(&pls->pkt);
2125 reset_packet(&pls->pkt);
2129 // If sub-demuxer reports updated metadata, copy it to the first stream
2130 // and set its AVSTREAM_EVENT_FLAG_METADATA_UPDATED flag.
2131 if (pls->ctx->event_flags & AVFMT_EVENT_FLAG_METADATA_UPDATED) {
2132 if (pls->n_main_streams) {
2133 st = pls->main_streams[0];
2134 av_dict_copy(&st->metadata, pls->ctx->metadata, 0);
2135 st->event_flags |= AVSTREAM_EVENT_FLAG_METADATA_UPDATED;
2137 pls->ctx->event_flags &= ~AVFMT_EVENT_FLAG_METADATA_UPDATED;
2140 /* check if noheader flag has been cleared by the subdemuxer */
2141 if (pls->has_noheader_flag && !(pls->ctx->ctx_flags & AVFMTCTX_NOHEADER)) {
2142 pls->has_noheader_flag = 0;
2143 update_noheader_flag(s);
2146 if (pls->pkt.stream_index >= pls->n_main_streams) {
2147 av_log(s, AV_LOG_ERROR, "stream index inconsistency: index %d, %d main streams, %d subdemuxer streams\n",
2148 pls->pkt.stream_index, pls->n_main_streams, pls->ctx->nb_streams);
2149 av_packet_unref(&pls->pkt);
2150 reset_packet(&pls->pkt);
2154 ist = pls->ctx->streams[pls->pkt.stream_index];
2155 st = pls->main_streams[pls->pkt.stream_index];
2158 pkt->stream_index = st->index;
2159 reset_packet(&c->playlists[minplaylist]->pkt);
2161 if (pkt->dts != AV_NOPTS_VALUE)
2162 c->cur_timestamp = av_rescale_q(pkt->dts,
2166 /* There may be more situations where this would be useful, but this at least
2167 * handles newly probed codecs properly (i.e. request_probe by mpegts). */
2168 if (ist->codecpar->codec_id != st->codecpar->codec_id) {
2169 ret = set_stream_info_from_input_stream(st, pls, ist);
2171 av_packet_unref(pkt);
2181 static int hls_read_seek(AVFormatContext *s, int stream_index,
2182 int64_t timestamp, int flags)
2184 HLSContext *c = s->priv_data;
2185 struct playlist *seek_pls = NULL;
2188 int stream_subdemuxer_index;
2189 int64_t first_timestamp, seek_timestamp, duration;
2191 if ((flags & AVSEEK_FLAG_BYTE) || (c->ctx->ctx_flags & AVFMTCTX_UNSEEKABLE))
2192 return AVERROR(ENOSYS);
2194 first_timestamp = c->first_timestamp == AV_NOPTS_VALUE ?
2195 0 : c->first_timestamp;
2197 seek_timestamp = av_rescale_rnd(timestamp, AV_TIME_BASE,
2198 s->streams[stream_index]->time_base.den,
2199 flags & AVSEEK_FLAG_BACKWARD ?
2200 AV_ROUND_DOWN : AV_ROUND_UP);
2202 duration = s->duration == AV_NOPTS_VALUE ?
2205 if (0 < duration && duration < seek_timestamp - first_timestamp)
2206 return AVERROR(EIO);
2208 /* find the playlist with the specified stream */
2209 for (i = 0; i < c->n_playlists; i++) {
2210 struct playlist *pls = c->playlists[i];
2211 for (j = 0; j < pls->n_main_streams; j++) {
2212 if (pls->main_streams[j] == s->streams[stream_index]) {
2214 stream_subdemuxer_index = j;
2219 /* check if the timestamp is valid for the playlist with the
2220 * specified stream index */
2221 if (!seek_pls || !find_timestamp_in_playlist(c, seek_pls, seek_timestamp, &seq_no))
2222 return AVERROR(EIO);
2224 /* set segment now so we do not need to search again below */
2225 seek_pls->cur_seq_no = seq_no;
2226 seek_pls->seek_stream_index = stream_subdemuxer_index;
2228 for (i = 0; i < c->n_playlists; i++) {
2230 struct playlist *pls = c->playlists[i];
2232 ff_format_io_close(pls->parent, &pls->input);
2233 pls->input_read_done = 0;
2234 if (pls->input_next)
2235 ff_format_io_close(pls->parent, &pls->input_next);
2236 pls->input_next_requested = 0;
2237 av_packet_unref(&pls->pkt);
2238 reset_packet(&pls->pkt);
2239 pls->pb.eof_reached = 0;
2240 /* Clear any buffered data */
2241 pls->pb.buf_end = pls->pb.buf_ptr = pls->pb.buffer;
2242 /* Reset the pos, to let the mpegts demuxer know we've seeked. */
2244 /* Flush the packet queue of the subdemuxer. */
2245 ff_read_frame_flush(pls->ctx);
2247 pls->seek_timestamp = seek_timestamp;
2248 pls->seek_flags = flags;
2250 if (pls != seek_pls) {
2251 /* set closest segment seq_no for playlists not handled above */
2252 find_timestamp_in_playlist(c, pls, seek_timestamp, &pls->cur_seq_no);
2253 /* seek the playlist to the given position without taking
2254 * keyframes into account since this playlist does not have the
2255 * specified stream where we should look for the keyframes */
2256 pls->seek_stream_index = -1;
2257 pls->seek_flags |= AVSEEK_FLAG_ANY;
2261 c->cur_timestamp = seek_timestamp;
2266 static int hls_probe(AVProbeData *p)
2268 /* Require #EXTM3U at the start, and either one of the ones below
2269 * somewhere for a proper match. */
2270 if (strncmp(p->buf, "#EXTM3U", 7))
2273 if (strstr(p->buf, "#EXT-X-STREAM-INF:") ||
2274 strstr(p->buf, "#EXT-X-TARGETDURATION:") ||
2275 strstr(p->buf, "#EXT-X-MEDIA-SEQUENCE:"))
2276 return AVPROBE_SCORE_MAX;
2280 #define OFFSET(x) offsetof(HLSContext, x)
2281 #define FLAGS AV_OPT_FLAG_DECODING_PARAM
2282 static const AVOption hls_options[] = {
2283 {"live_start_index", "segment index to start live streams at (negative values are from the end)",
2284 OFFSET(live_start_index), AV_OPT_TYPE_INT, {.i64 = -3}, INT_MIN, INT_MAX, FLAGS},
2285 {"allowed_extensions", "List of file extensions that hls is allowed to access",
2286 OFFSET(allowed_extensions), AV_OPT_TYPE_STRING,
2287 {.str = "3gp,aac,avi,flac,mkv,m3u8,m4a,m4s,m4v,mpg,mov,mp2,mp3,mp4,mpeg,mpegts,ogg,ogv,oga,ts,vob,wav"},
2288 INT_MIN, INT_MAX, FLAGS},
2289 {"max_reload", "Maximum number of times a insufficient list is attempted to be reloaded",
2290 OFFSET(max_reload), AV_OPT_TYPE_INT, {.i64 = 1000}, 0, INT_MAX, FLAGS},
2291 {"http_persistent", "Use persistent HTTP connections",
2292 OFFSET(http_persistent), AV_OPT_TYPE_BOOL, {.i64 = 1}, 0, 1, FLAGS },
2293 {"http_multiple", "Use multiple HTTP connections for fetching segments",
2294 OFFSET(http_multiple), AV_OPT_TYPE_BOOL, {.i64 = -1}, -1, 1, FLAGS},
2298 static const AVClass hls_class = {
2299 .class_name = "hls,applehttp",
2300 .item_name = av_default_item_name,
2301 .option = hls_options,
2302 .version = LIBAVUTIL_VERSION_INT,
2305 AVInputFormat ff_hls_demuxer = {
2306 .name = "hls,applehttp",
2307 .long_name = NULL_IF_CONFIG_SMALL("Apple HTTP Live Streaming"),
2308 .priv_class = &hls_class,
2309 .priv_data_size = sizeof(HLSContext),
2310 .flags = AVFMT_NOGENSEARCH,
2311 .read_probe = hls_probe,
2312 .read_header = hls_read_header,
2313 .read_packet = hls_read_packet,
2314 .read_close = hls_close,
2315 .read_seek = hls_read_seek,