1/*
2 * Apple HTTP Live Streaming Protocol Handler
3 * Copyright (c) 2010 Martin Storsjo
4 *
5 * This file is part of Libav.
6 *
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.
11 *
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.
16 *
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
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 "avformat.h"
30#include "internal.h"
31#include "url.h"
32#include <unistd.h>
33
34/*
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
40 * playlists.
41 *
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.
44 */
45
46struct segment {
47    int duration;
48    char url[MAX_URL_SIZE];
49};
50
51struct variant {
52    int bandwidth;
53    char url[MAX_URL_SIZE];
54};
55
56typedef struct AppleHTTPContext {
57    char playlisturl[MAX_URL_SIZE];
58    int target_duration;
59    int start_seq_no;
60    int finished;
61    int n_segments;
62    struct segment **segments;
63    int n_variants;
64    struct variant **variants;
65    int cur_seq_no;
66    URLContext *seg_hd;
67    int64_t last_load_time;
68} AppleHTTPContext;
69
70static int read_chomp_line(AVIOContext *s, char *buf, int maxlen)
71{
72    int len = ff_get_line(s, buf, maxlen);
73    while (len > 0 && isspace(buf[len - 1]))
74        buf[--len] = '\0';
75    return len;
76}
77
78static void free_segment_list(AppleHTTPContext *s)
79{
80    int i;
81    for (i = 0; i < s->n_segments; i++)
82        av_free(s->segments[i]);
83    av_freep(&s->segments);
84    s->n_segments = 0;
85}
86
87static void free_variant_list(AppleHTTPContext *s)
88{
89    int i;
90    for (i = 0; i < s->n_variants; i++)
91        av_free(s->variants[i]);
92    av_freep(&s->variants);
93    s->n_variants = 0;
94}
95
96struct variant_info {
97    char bandwidth[20];
98};
99
100static void handle_variant_args(struct variant_info *info, const char *key,
101                                int key_len, char **dest, int *dest_len)
102{
103    if (!strncmp(key, "BANDWIDTH=", key_len)) {
104        *dest     =        info->bandwidth;
105        *dest_len = sizeof(info->bandwidth);
106    }
107}
108
109static int parse_playlist(URLContext *h, const char *url)
110{
111    AppleHTTPContext *s = h->priv_data;
112    AVIOContext *in;
113    int ret = 0, duration = 0, is_segment = 0, is_variant = 0, bandwidth = 0;
114    char line[1024];
115    const char *ptr;
116
117    if ((ret = avio_open2(&in, url, AVIO_FLAG_READ,
118                          &h->interrupt_callback, NULL)) < 0)
119        return ret;
120
121    read_chomp_line(in, line, sizeof(line));
122    if (strcmp(line, "#EXTM3U"))
123        return AVERROR_INVALIDDATA;
124
125    free_segment_list(s);
126    s->finished = 0;
127    while (!in->eof_reached) {
128        read_chomp_line(in, line, sizeof(line));
129        if (av_strstart(line, "#EXT-X-STREAM-INF:", &ptr)) {
130            struct variant_info info = {{0}};
131            is_variant = 1;
132            ff_parse_key_value(ptr, (ff_parse_key_val_cb) handle_variant_args,
133                               &info);
134            bandwidth = atoi(info.bandwidth);
135        } else if (av_strstart(line, "#EXT-X-TARGETDURATION:", &ptr)) {
136            s->target_duration = atoi(ptr);
137        } else if (av_strstart(line, "#EXT-X-MEDIA-SEQUENCE:", &ptr)) {
138            s->start_seq_no = atoi(ptr);
139        } else if (av_strstart(line, "#EXT-X-ENDLIST", &ptr)) {
140            s->finished = 1;
141        } else if (av_strstart(line, "#EXTINF:", &ptr)) {
142            is_segment = 1;
143            duration = atoi(ptr);
144        } else if (av_strstart(line, "#", NULL)) {
145            continue;
146        } else if (line[0]) {
147            if (is_segment) {
148                struct segment *seg = av_malloc(sizeof(struct segment));
149                if (!seg) {
150                    ret = AVERROR(ENOMEM);
151                    goto fail;
152                }
153                seg->duration = duration;
154                ff_make_absolute_url(seg->url, sizeof(seg->url), url, line);
155                dynarray_add(&s->segments, &s->n_segments, seg);
156                is_segment = 0;
157            } else if (is_variant) {
158                struct variant *var = av_malloc(sizeof(struct variant));
159                if (!var) {
160                    ret = AVERROR(ENOMEM);
161                    goto fail;
162                }
163                var->bandwidth = bandwidth;
164                ff_make_absolute_url(var->url, sizeof(var->url), url, line);
165                dynarray_add(&s->variants, &s->n_variants, var);
166                is_variant = 0;
167            }
168        }
169    }
170    s->last_load_time = av_gettime();
171
172fail:
173    avio_close(in);
174    return ret;
175}
176
177static int applehttp_close(URLContext *h)
178{
179    AppleHTTPContext *s = h->priv_data;
180
181    free_segment_list(s);
182    free_variant_list(s);
183    ffurl_close(s->seg_hd);
184    return 0;
185}
186
187static int applehttp_open(URLContext *h, const char *uri, int flags)
188{
189    AppleHTTPContext *s = h->priv_data;
190    int ret, i;
191    const char *nested_url;
192
193    if (flags & AVIO_FLAG_WRITE)
194        return AVERROR(ENOSYS);
195
196    h->is_streamed = 1;
197
198    if (av_strstart(uri, "applehttp+", &nested_url)) {
199        av_strlcpy(s->playlisturl, nested_url, sizeof(s->playlisturl));
200    } else if (av_strstart(uri, "applehttp://", &nested_url)) {
201        av_strlcpy(s->playlisturl, "http://", sizeof(s->playlisturl));
202        av_strlcat(s->playlisturl, nested_url, sizeof(s->playlisturl));
203    } else {
204        av_log(h, AV_LOG_ERROR, "Unsupported url %s\n", uri);
205        ret = AVERROR(EINVAL);
206        goto fail;
207    }
208
209    if ((ret = parse_playlist(h, s->playlisturl)) < 0)
210        goto fail;
211
212    if (s->n_segments == 0 && s->n_variants > 0) {
213        int max_bandwidth = 0, maxvar = -1;
214        for (i = 0; i < s->n_variants; i++) {
215            if (s->variants[i]->bandwidth > max_bandwidth || i == 0) {
216                max_bandwidth = s->variants[i]->bandwidth;
217                maxvar = i;
218            }
219        }
220        av_strlcpy(s->playlisturl, s->variants[maxvar]->url,
221                   sizeof(s->playlisturl));
222        if ((ret = parse_playlist(h, s->playlisturl)) < 0)
223            goto fail;
224    }
225
226    if (s->n_segments == 0) {
227        av_log(h, AV_LOG_WARNING, "Empty playlist\n");
228        ret = AVERROR(EIO);
229        goto fail;
230    }
231    s->cur_seq_no = s->start_seq_no;
232    if (!s->finished && s->n_segments >= 3)
233        s->cur_seq_no = s->start_seq_no + s->n_segments - 3;
234
235    return 0;
236
237fail:
238    applehttp_close(h);
239    return ret;
240}
241
242static int applehttp_read(URLContext *h, uint8_t *buf, int size)
243{
244    AppleHTTPContext *s = h->priv_data;
245    const char *url;
246    int ret;
247    int64_t reload_interval;
248
249start:
250    if (s->seg_hd) {
251        ret = ffurl_read(s->seg_hd, buf, size);
252        if (ret > 0)
253            return ret;
254    }
255    if (s->seg_hd) {
256        ffurl_close(s->seg_hd);
257        s->seg_hd = NULL;
258        s->cur_seq_no++;
259    }
260    reload_interval = s->n_segments > 0 ?
261                      s->segments[s->n_segments - 1]->duration :
262                      s->target_duration;
263    reload_interval *= 1000000;
264retry:
265    if (!s->finished) {
266        int64_t now = av_gettime();
267        if (now - s->last_load_time >= reload_interval) {
268            if ((ret = parse_playlist(h, s->playlisturl)) < 0)
269                return ret;
270            /* If we need to reload the playlist again below (if
271             * there's still no more segments), switch to a reload
272             * interval of half the target duration. */
273            reload_interval = s->target_duration * 500000;
274        }
275    }
276    if (s->cur_seq_no < s->start_seq_no) {
277        av_log(h, AV_LOG_WARNING,
278               "skipping %d segments ahead, expired from playlist\n",
279               s->start_seq_no - s->cur_seq_no);
280        s->cur_seq_no = s->start_seq_no;
281    }
282    if (s->cur_seq_no - s->start_seq_no >= s->n_segments) {
283        if (s->finished)
284            return AVERROR_EOF;
285        while (av_gettime() - s->last_load_time < reload_interval) {
286            if (ff_check_interrupt(&h->interrupt_callback))
287                return AVERROR_EXIT;
288            usleep(100*1000);
289        }
290        goto retry;
291    }
292    url = s->segments[s->cur_seq_no - s->start_seq_no]->url,
293    av_log(h, AV_LOG_DEBUG, "opening %s\n", url);
294    ret = ffurl_open(&s->seg_hd, url, AVIO_FLAG_READ,
295                     &h->interrupt_callback, NULL);
296    if (ret < 0) {
297        if (ff_check_interrupt(&h->interrupt_callback))
298            return AVERROR_EXIT;
299        av_log(h, AV_LOG_WARNING, "Unable to open %s\n", url);
300        s->cur_seq_no++;
301        goto retry;
302    }
303    goto start;
304}
305
306URLProtocol ff_applehttp_protocol = {
307    .name           = "applehttp",
308    .url_open       = applehttp_open,
309    .url_read       = applehttp_read,
310    .url_close      = applehttp_close,
311    .flags          = URL_PROTOCOL_FLAG_NESTED_SCHEME,
312    .priv_data_size = sizeof(AppleHTTPContext),
313};
314