2 * Apple HTTP Live Streaming demuxer
3 * Copyright (c) 2010 Martin Storsjo
5 * This file is part of Libav.
7 * Libav 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.
12 * Libav 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.
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with Libav; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
24 * Apple HTTP Live Streaming demuxer
25 * http://tools.ietf.org/html/draft-pantos-http-live-streaming
28 #define _XOPEN_SOURCE 600
29 #include "libavutil/avstring.h"
35 * An apple http stream consists of a playlist with media segment files,
36 * played sequentially. There may be several playlists with the same
37 * video content, in different bandwidth variants, that are played in
38 * parallel (preferrably only one bandwidth variant at a time). In this case,
39 * the user supplied the url to a main playlist that only lists the variant
42 * If the main playlist doesn't point at any variants, we still create
43 * one anonymous toplevel variant for this, to maintain the structure.
48 char url[MAX_URL_SIZE];
52 * Each variant has its own demuxer. If it currently is active,
53 * it has an open AVIOContext too, and potentially an AVPacket
54 * containing the next packet from this stream.
58 char url[MAX_URL_SIZE];
66 struct segment **segments;
70 typedef struct AppleHTTPContext {
74 struct variant **variants;
76 int64_t last_load_time;
77 int64_t last_packet_dts;
78 int max_start_seq, min_end_seq;
81 static int read_chomp_line(AVIOContext *s, char *buf, int maxlen)
83 int len = ff_get_line(s, buf, maxlen);
84 while (len > 0 && isspace(buf[len - 1]))
89 static void free_segment_list(struct variant *var)
92 for (i = 0; i < var->n_segments; i++)
93 av_free(var->segments[i]);
94 av_freep(&var->segments);
98 static void free_variant_list(AppleHTTPContext *c)
101 for (i = 0; i < c->n_variants; i++) {
102 struct variant *var = c->variants[i];
103 free_segment_list(var);
104 av_free_packet(&var->pkt);
109 av_close_input_file(var->ctx);
113 av_freep(&c->variants);
118 * Used to reset a statically allocated AVPacket to a clean slate,
119 * containing no data.
121 static void reset_packet(AVPacket *pkt)
127 static struct variant *new_variant(AppleHTTPContext *c, int bandwidth,
128 const char *url, const char *base)
130 struct variant *var = av_mallocz(sizeof(struct variant));
133 reset_packet(&var->pkt);
134 var->bandwidth = bandwidth;
135 ff_make_absolute_url(var->url, sizeof(var->url), base, url);
136 dynarray_add(&c->variants, &c->n_variants, var);
140 struct variant_info {
144 static void handle_variant_args(struct variant_info *info, const char *key,
145 int key_len, char **dest, int *dest_len)
147 if (!strncmp(key, "BANDWIDTH=", key_len)) {
148 *dest = info->bandwidth;
149 *dest_len = sizeof(info->bandwidth);
153 static int parse_playlist(AppleHTTPContext *c, const char *url,
154 struct variant *var, AVIOContext *in)
156 int ret = 0, duration = 0, is_segment = 0, is_variant = 0, bandwidth = 0;
163 if ((ret = avio_open(&in, url, URL_RDONLY)) < 0)
167 read_chomp_line(in, line, sizeof(line));
168 if (strcmp(line, "#EXTM3U")) {
169 ret = AVERROR_INVALIDDATA;
174 free_segment_list(var);
176 while (!in->eof_reached) {
177 read_chomp_line(in, line, sizeof(line));
178 if (av_strstart(line, "#EXT-X-STREAM-INF:", &ptr)) {
179 struct variant_info info = {{0}};
181 ff_parse_key_value(ptr, (ff_parse_key_val_cb) handle_variant_args,
183 bandwidth = atoi(info.bandwidth);
184 } else if (av_strstart(line, "#EXT-X-TARGETDURATION:", &ptr)) {
185 c->target_duration = atoi(ptr);
186 } else if (av_strstart(line, "#EXT-X-MEDIA-SEQUENCE:", &ptr)) {
188 var = new_variant(c, 0, url, NULL);
190 ret = AVERROR(ENOMEM);
194 var->start_seq_no = atoi(ptr);
195 } else if (av_strstart(line, "#EXT-X-ENDLIST", &ptr)) {
197 } else if (av_strstart(line, "#EXTINF:", &ptr)) {
199 duration = atoi(ptr);
200 } else if (av_strstart(line, "#", NULL)) {
202 } else if (line[0]) {
204 if (!new_variant(c, bandwidth, line, url)) {
205 ret = AVERROR(ENOMEM);
214 var = new_variant(c, 0, url, NULL);
216 ret = AVERROR(ENOMEM);
220 seg = av_malloc(sizeof(struct segment));
222 ret = AVERROR(ENOMEM);
225 seg->duration = duration;
226 ff_make_absolute_url(seg->url, sizeof(seg->url), url, line);
227 dynarray_add(&var->segments, &var->n_segments, seg);
232 c->last_load_time = av_gettime();
240 static int applehttp_read_header(AVFormatContext *s, AVFormatParameters *ap)
242 AppleHTTPContext *c = s->priv_data;
243 int ret = 0, i, j, stream_offset = 0;
245 if ((ret = parse_playlist(c, s->filename, NULL, s->pb)) < 0)
248 if (c->n_variants == 0) {
249 av_log(NULL, AV_LOG_WARNING, "Empty playlist\n");
253 /* If the playlist only contained variants, parse each individual
254 * variant playlist. */
255 if (c->n_variants > 1 || c->variants[0]->n_segments == 0) {
256 for (i = 0; i < c->n_variants; i++) {
257 struct variant *v = c->variants[i];
258 if ((ret = parse_playlist(c, v->url, v, NULL)) < 0)
263 if (c->variants[0]->n_segments == 0) {
264 av_log(NULL, AV_LOG_WARNING, "Empty playlist\n");
269 /* If this isn't a live stream, calculate the total duration of the
272 int64_t duration = 0;
273 for (i = 0; i < c->variants[0]->n_segments; i++)
274 duration += c->variants[0]->segments[i]->duration;
275 s->duration = duration * AV_TIME_BASE;
278 c->min_end_seq = INT_MAX;
279 /* Open the demuxer for each variant */
280 for (i = 0; i < c->n_variants; i++) {
281 struct variant *v = c->variants[i];
282 if (v->n_segments == 0)
284 c->max_start_seq = FFMAX(c->max_start_seq, v->start_seq_no);
285 c->min_end_seq = FFMIN(c->min_end_seq, v->start_seq_no +
287 ret = av_open_input_file(&v->ctx, v->segments[0]->url, NULL, 0, NULL);
290 avio_close(v->ctx->pb);
292 v->stream_offset = stream_offset;
293 /* Create new AVStreams for each stream in this variant */
294 for (j = 0; j < v->ctx->nb_streams; j++) {
295 AVStream *st = av_new_stream(s, i);
297 ret = AVERROR(ENOMEM);
300 avcodec_copy_context(st->codec, v->ctx->streams[j]->codec);
302 stream_offset += v->ctx->nb_streams;
304 c->last_packet_dts = AV_NOPTS_VALUE;
306 c->cur_seq_no = c->max_start_seq;
307 /* If this is a live stream with more than 3 segments, start at the
308 * third last segment. */
309 if (!c->finished && c->min_end_seq - c->max_start_seq > 3)
310 c->cur_seq_no = c->min_end_seq - 2;
314 free_variant_list(c);
318 static int open_variant(AppleHTTPContext *c, struct variant *var, int skip)
322 if (c->cur_seq_no < var->start_seq_no) {
323 av_log(NULL, AV_LOG_WARNING,
324 "seq %d not available in variant %s, skipping\n",
325 var->start_seq_no, var->url);
328 if (c->cur_seq_no - var->start_seq_no >= var->n_segments)
329 return c->finished ? AVERROR_EOF : 0;
330 ret = avio_open(&var->pb,
331 var->segments[c->cur_seq_no - var->start_seq_no]->url,
335 var->ctx->pb = var->pb;
336 /* If this is a new segment in parallel with another one already opened,
337 * skip ahead so they're all at the same dts. */
338 if (skip && c->last_packet_dts != AV_NOPTS_VALUE) {
340 ret = av_read_frame(var->ctx, &var->pkt);
342 if (ret == AVERROR_EOF) {
343 reset_packet(&var->pkt);
348 if (var->pkt.dts >= c->last_packet_dts)
350 av_free_packet(&var->pkt);
356 static int applehttp_read_packet(AVFormatContext *s, AVPacket *pkt)
358 AppleHTTPContext *c = s->priv_data;
359 int ret, i, minvariant = -1, first = 1, needed = 0, changed = 0,
362 /* Recheck the discard flags - which streams are desired at the moment */
363 for (i = 0; i < c->n_variants; i++)
364 c->variants[i]->needed = 0;
365 for (i = 0; i < s->nb_streams; i++) {
366 AVStream *st = s->streams[i];
367 struct variant *var = c->variants[s->streams[i]->id];
368 if (st->discard < AVDISCARD_ALL) {
372 /* Copy the discard flag to the chained demuxer, to indicate which
373 * streams are desired. */
374 var->ctx->streams[i - var->stream_offset]->discard = st->discard;
379 for (i = 0; i < c->n_variants; i++) {
380 struct variant *var = c->variants[i];
381 /* Close unneeded streams, open newly requested streams */
382 if (var->pb && !var->needed) {
383 av_log(s, AV_LOG_DEBUG,
384 "Closing variant stream %d, no longer needed\n", i);
385 av_free_packet(&var->pkt);
386 reset_packet(&var->pkt);
390 } else if (!var->pb && var->needed) {
392 av_log(s, AV_LOG_DEBUG, "Opening variant stream %d\n", i);
393 if (first && !c->finished)
394 if ((ret = parse_playlist(c, var->url, var, NULL)) < 0)
396 ret = open_variant(c, var, first);
401 /* Count the number of open variants */
404 /* Make sure we've got one buffered packet from each open variant
406 if (var->pb && !var->pkt.data) {
407 ret = av_read_frame(var->ctx, &var->pkt);
409 if (!var->pb->eof_reached)
411 reset_packet(&var->pkt);
414 /* Check if this stream has the packet with the lowest dts */
416 if (minvariant < 0 ||
417 var->pkt.dts < c->variants[minvariant]->pkt.dts)
421 if (first && changed)
422 av_log(s, AV_LOG_INFO, "Receiving %d variant streams\n", variants);
423 /* If we got a packet, return it */
424 if (minvariant >= 0) {
425 *pkt = c->variants[minvariant]->pkt;
426 pkt->stream_index += c->variants[minvariant]->stream_offset;
427 reset_packet(&c->variants[minvariant]->pkt);
428 c->last_packet_dts = pkt->dts;
431 /* No more packets - eof reached in all variant streams, close the
432 * current segments. */
433 for (i = 0; i < c->n_variants; i++) {
434 struct variant *var = c->variants[i];
440 /* Indicate that we're opening the next segment, not opening a new
441 * variant stream in parallel, so we shouldn't try to skip ahead. */
446 /* If this is a live stream and target_duration has elapsed since
447 * the last playlist reload, reload the variant playlists now. */
448 int64_t now = av_gettime();
449 if (now - c->last_load_time >= c->target_duration*1000000) {
450 c->max_start_seq = 0;
451 c->min_end_seq = INT_MAX;
452 for (i = 0; i < c->n_variants; i++) {
453 struct variant *var = c->variants[i];
455 if ((ret = parse_playlist(c, var->url, var, NULL)) < 0)
457 c->max_start_seq = FFMAX(c->max_start_seq,
459 c->min_end_seq = FFMIN(c->min_end_seq,
460 var->start_seq_no + var->n_segments);
465 if (c->cur_seq_no < c->max_start_seq) {
466 av_log(NULL, AV_LOG_WARNING,
467 "skipping %d segments ahead, expired from playlists\n",
468 c->max_start_seq - c->cur_seq_no);
469 c->cur_seq_no = c->max_start_seq;
471 /* If more segments exist, open the next one */
472 if (c->cur_seq_no < c->min_end_seq)
474 /* We've reached the end of the playlists - return eof if this is a
475 * non-live stream, wait until the next playlist reload if it is live. */
478 while (av_gettime() - c->last_load_time < c->target_duration*1000000) {
479 if (url_interrupt_cb())
483 /* Enough time has elapsed since the last reload */
487 static int applehttp_close(AVFormatContext *s)
489 AppleHTTPContext *c = s->priv_data;
491 free_variant_list(c);
495 static int applehttp_read_seek(AVFormatContext *s, int stream_index,
496 int64_t timestamp, int flags)
498 AppleHTTPContext *c = s->priv_data;
501 struct variant *var = c->variants[0];
503 if ((flags & AVSEEK_FLAG_BYTE) || !c->finished)
504 return AVERROR(ENOSYS);
506 /* Reset the variants */
507 c->last_packet_dts = AV_NOPTS_VALUE;
508 for (i = 0; i < c->n_variants; i++) {
509 struct variant *var = c->variants[i];
514 av_free_packet(&var->pkt);
515 reset_packet(&var->pkt);
518 timestamp = av_rescale_rnd(timestamp, 1, stream_index >= 0 ?
519 s->streams[stream_index]->time_base.den :
520 AV_TIME_BASE, flags & AVSEEK_FLAG_BACKWARD ?
521 AV_ROUND_DOWN : AV_ROUND_UP);
522 /* Locate the segment that contains the target timestamp */
523 for (i = 0; i < var->n_segments; i++) {
524 if (timestamp >= pos && timestamp < pos + var->segments[i]->duration) {
525 c->cur_seq_no = var->start_seq_no + i;
528 pos += var->segments[i]->duration;
533 static int applehttp_probe(AVProbeData *p)
535 /* Require #EXTM3U at the start, and either one of the ones below
536 * somewhere for a proper match. */
537 if (strncmp(p->buf, "#EXTM3U", 7))
539 if (strstr(p->buf, "#EXT-X-STREAM-INF:") ||
540 strstr(p->buf, "#EXT-X-TARGETDURATION:") ||
541 strstr(p->buf, "#EXT-X-MEDIA-SEQUENCE:"))
542 return AVPROBE_SCORE_MAX;
546 AVInputFormat ff_applehttp_demuxer = {
548 NULL_IF_CONFIG_SMALL("Apple HTTP Live Streaming format"),
549 sizeof(AppleHTTPContext),
551 applehttp_read_header,
552 applehttp_read_packet,