1/*
2 * Apple HTTP Live Streaming Protocol Handler
3 * Copyright (c) 2010 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/**
23 * @file
24 * Apple HTTP Live Streaming Protocol Handler
25 * http://tools.ietf.org/html/draft-pantos-http-live-streaming
26 */
27
28#include "libavutil/avstring.h"
29#include "libavutil/time.h"
30#include "avformat.h"
31#include "internal.h"
32#include "url.h"
33#include "version.h"
34
35/*
36 * An apple http stream consists of a playlist with media segment files,
37 * played sequentially. There may be several playlists with the same
38 * video content, in different bandwidth variants, that are played in
39 * parallel (preferably only one bandwidth variant at a time). In this case,
40 * the user supplied the url to a main playlist that only lists the variant
41 * playlists.
42 *
43 * If the main playlist doesn't point at any variants, we still create
44 * one anonymous toplevel variant for this, to maintain the structure.
45 */
46
47struct segment {
48    int64_t duration;
49    char url[MAX_URL_SIZE];
50};
51
52struct variant {
53    int bandwidth;
54    char url[MAX_URL_SIZE];
55};
56
57typedef struct HLSContext {
58    char playlisturl[MAX_URL_SIZE];
59    int64_t target_duration;
60    int start_seq_no;
61    int finished;
62    int n_segments;
63    struct segment **segments;
64    int n_variants;
65    struct variant **variants;
66    int cur_seq_no;
67    URLContext *seg_hd;
68    int64_t last_load_time;
69} HLSContext;
70
71static int read_chomp_line(AVIOContext *s, char *buf, int maxlen)
72{
73    int len = ff_get_line(s, buf, maxlen);
74    while (len > 0 && av_isspace(buf[len - 1]))
75        buf[--len] = '\0';
76    return len;
77}
78
79static void free_segment_list(HLSContext *s)
80{
81    int i;
82    for (i = 0; i < s->n_segments; i++)
83        av_free(s->segments[i]);
84    av_freep(&s->segments);
85    s->n_segments = 0;
86}
87
88static void free_variant_list(HLSContext *s)
89{
90    int i;
91    for (i = 0; i < s->n_variants; i++)
92        av_free(s->variants[i]);
93    av_freep(&s->variants);
94    s->n_variants = 0;
95}
96
97struct variant_info {
98    char bandwidth[20];
99};
100
101static void handle_variant_args(struct variant_info *info, const char *key,
102                                int key_len, char **dest, int *dest_len)
103{
104    if (!strncmp(key, "BANDWIDTH=", key_len)) {
105        *dest     =        info->bandwidth;
106        *dest_len = sizeof(info->bandwidth);
107    }
108}
109
110static int parse_playlist(URLContext *h, const char *url)
111{
112    HLSContext *s = h->priv_data;
113    AVIOContext *in;
114    int ret = 0, is_segment = 0, is_variant = 0, bandwidth = 0;
115    int64_t duration = 0;
116    char line[1024];
117    const char *ptr;
118
119    if ((ret = avio_open2(&in, url, AVIO_FLAG_READ,
120                          &h->interrupt_callback, NULL)) < 0)
121        return ret;
122
123    read_chomp_line(in, line, sizeof(line));
124    if (strcmp(line, "#EXTM3U"))
125        return AVERROR_INVALIDDATA;
126
127    free_segment_list(s);
128    s->finished = 0;
129    while (!url_feof(in)) {
130        read_chomp_line(in, line, sizeof(line));
131        if (av_strstart(line, "#EXT-X-STREAM-INF:", &ptr)) {
132            struct variant_info info = {{0}};
133            is_variant = 1;
134            ff_parse_key_value(ptr, (ff_parse_key_val_cb) handle_variant_args,
135                               &info);
136            bandwidth = atoi(info.bandwidth);
137        } else if (av_strstart(line, "#EXT-X-TARGETDURATION:", &ptr)) {
138            s->target_duration = atoi(ptr) * AV_TIME_BASE;
139        } else if (av_strstart(line, "#EXT-X-MEDIA-SEQUENCE:", &ptr)) {
140            s->start_seq_no = atoi(ptr);
141        } else if (av_strstart(line, "#EXT-X-ENDLIST", &ptr)) {
142            s->finished = 1;
143        } else if (av_strstart(line, "#EXTINF:", &ptr)) {
144            is_segment = 1;
145            duration = atof(ptr) * AV_TIME_BASE;
146        } else if (av_strstart(line, "#", NULL)) {
147            continue;
148        } else if (line[0]) {
149            if (is_segment) {
150                struct segment *seg = av_malloc(sizeof(struct segment));
151                if (!seg) {
152                    ret = AVERROR(ENOMEM);
153                    goto fail;
154                }
155                seg->duration = duration;
156                ff_make_absolute_url(seg->url, sizeof(seg->url), url, line);
157                dynarray_add(&s->segments, &s->n_segments, seg);
158                is_segment = 0;
159            } else if (is_variant) {
160                struct variant *var = av_malloc(sizeof(struct variant));
161                if (!var) {
162                    ret = AVERROR(ENOMEM);
163                    goto fail;
164                }
165                var->bandwidth = bandwidth;
166                ff_make_absolute_url(var->url, sizeof(var->url), url, line);
167                dynarray_add(&s->variants, &s->n_variants, var);
168                is_variant = 0;
169            }
170        }
171    }
172    s->last_load_time = av_gettime();
173
174fail:
175    avio_close(in);
176    return ret;
177}
178
179static int hls_close(URLContext *h)
180{
181    HLSContext *s = h->priv_data;
182
183    free_segment_list(s);
184    free_variant_list(s);
185    ffurl_close(s->seg_hd);
186    return 0;
187}
188
189static int hls_open(URLContext *h, const char *uri, int flags)
190{
191    HLSContext *s = h->priv_data;
192    int ret, i;
193    const char *nested_url;
194
195    if (flags & AVIO_FLAG_WRITE)
196        return AVERROR(ENOSYS);
197
198    h->is_streamed = 1;
199
200    if (av_strstart(uri, "hls+", &nested_url)) {
201        av_strlcpy(s->playlisturl, nested_url, sizeof(s->playlisturl));
202    } else if (av_strstart(uri, "hls://", &nested_url)) {
203        av_log(h, AV_LOG_ERROR,
204               "No nested protocol specified. Specify e.g. hls+http://%s\n",
205               nested_url);
206        ret = AVERROR(EINVAL);
207        goto fail;
208    } else {
209        av_log(h, AV_LOG_ERROR, "Unsupported url %s\n", uri);
210        ret = AVERROR(EINVAL);
211        goto fail;
212    }
213    av_log(h, AV_LOG_WARNING,
214           "Using the hls protocol is discouraged, please try using the "
215           "hls demuxer instead. The hls demuxer should be more complete "
216           "and work as well as the protocol implementation. (If not, "
217           "please report it.) To use the demuxer, simply use %s as url.\n",
218           s->playlisturl);
219
220    if ((ret = parse_playlist(h, s->playlisturl)) < 0)
221        goto fail;
222
223    if (s->n_segments == 0 && s->n_variants > 0) {
224        int max_bandwidth = 0, maxvar = -1;
225        for (i = 0; i < s->n_variants; i++) {
226            if (s->variants[i]->bandwidth > max_bandwidth || i == 0) {
227                max_bandwidth = s->variants[i]->bandwidth;
228                maxvar = i;
229            }
230        }
231        av_strlcpy(s->playlisturl, s->variants[maxvar]->url,
232                   sizeof(s->playlisturl));
233        if ((ret = parse_playlist(h, s->playlisturl)) < 0)
234            goto fail;
235    }
236
237    if (s->n_segments == 0) {
238        av_log(h, AV_LOG_WARNING, "Empty playlist\n");
239        ret = AVERROR(EIO);
240        goto fail;
241    }
242    s->cur_seq_no = s->start_seq_no;
243    if (!s->finished && s->n_segments >= 3)
244        s->cur_seq_no = s->start_seq_no + s->n_segments - 3;
245
246    return 0;
247
248fail:
249    hls_close(h);
250    return ret;
251}
252
253static int hls_read(URLContext *h, uint8_t *buf, int size)
254{
255    HLSContext *s = h->priv_data;
256    const char *url;
257    int ret;
258    int64_t reload_interval;
259
260start:
261    if (s->seg_hd) {
262        ret = ffurl_read(s->seg_hd, buf, size);
263        if (ret > 0)
264            return ret;
265    }
266    if (s->seg_hd) {
267        ffurl_close(s->seg_hd);
268        s->seg_hd = NULL;
269        s->cur_seq_no++;
270    }
271    reload_interval = s->n_segments > 0 ?
272                      s->segments[s->n_segments - 1]->duration :
273                      s->target_duration;
274retry:
275    if (!s->finished) {
276        int64_t now = av_gettime();
277        if (now - s->last_load_time >= reload_interval) {
278            if ((ret = parse_playlist(h, s->playlisturl)) < 0)
279                return ret;
280            /* If we need to reload the playlist again below (if
281             * there's still no more segments), switch to a reload
282             * interval of half the target duration. */
283            reload_interval = s->target_duration / 2;
284        }
285    }
286    if (s->cur_seq_no < s->start_seq_no) {
287        av_log(h, AV_LOG_WARNING,
288               "skipping %d segments ahead, expired from playlist\n",
289               s->start_seq_no - s->cur_seq_no);
290        s->cur_seq_no = s->start_seq_no;
291    }
292    if (s->cur_seq_no - s->start_seq_no >= s->n_segments) {
293        if (s->finished)
294            return AVERROR_EOF;
295        while (av_gettime() - s->last_load_time < reload_interval) {
296            if (ff_check_interrupt(&h->interrupt_callback))
297                return AVERROR_EXIT;
298            av_usleep(100*1000);
299        }
300        goto retry;
301    }
302    url = s->segments[s->cur_seq_no - s->start_seq_no]->url,
303    av_log(h, AV_LOG_DEBUG, "opening %s\n", url);
304    ret = ffurl_open(&s->seg_hd, url, AVIO_FLAG_READ,
305                     &h->interrupt_callback, NULL);
306    if (ret < 0) {
307        if (ff_check_interrupt(&h->interrupt_callback))
308            return AVERROR_EXIT;
309        av_log(h, AV_LOG_WARNING, "Unable to open %s\n", url);
310        s->cur_seq_no++;
311        goto retry;
312    }
313    goto start;
314}
315
316URLProtocol ff_hls_protocol = {
317    .name           = "hls",
318    .url_open       = hls_open,
319    .url_read       = hls_read,
320    .url_close      = hls_close,
321    .flags          = URL_PROTOCOL_FLAG_NESTED_SCHEME,
322    .priv_data_size = sizeof(HLSContext),
323};
324