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libavformat/applehttpproto.c

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00001 /*
00002  * Apple HTTP Live Streaming Protocol Handler
00003  * Copyright (c) 2010 Martin Storsjo
00004  *
00005  * This file is part of FFmpeg.
00006  *
00007  * FFmpeg is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Lesser General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2.1 of the License, or (at your option) any later version.
00011  *
00012  * FFmpeg is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Lesser General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Lesser General Public
00018  * License along with FFmpeg; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 
00028 #include "libavutil/avstring.h"
00029 #include "avformat.h"
00030 #include "internal.h"
00031 #include "url.h"
00032 #include <unistd.h>
00033 
00034 /*
00035  * An apple http stream consists of a playlist with media segment files,
00036  * played sequentially. There may be several playlists with the same
00037  * video content, in different bandwidth variants, that are played in
00038  * parallel (preferrably only one bandwidth variant at a time). In this case,
00039  * the user supplied the url to a main playlist that only lists the variant
00040  * playlists.
00041  *
00042  * If the main playlist doesn't point at any variants, we still create
00043  * one anonymous toplevel variant for this, to maintain the structure.
00044  */
00045 
00046 struct segment {
00047     int duration;
00048     char url[MAX_URL_SIZE];
00049 };
00050 
00051 struct variant {
00052     int bandwidth;
00053     char url[MAX_URL_SIZE];
00054 };
00055 
00056 typedef struct AppleHTTPContext {
00057     char playlisturl[MAX_URL_SIZE];
00058     int target_duration;
00059     int start_seq_no;
00060     int finished;
00061     int n_segments;
00062     struct segment **segments;
00063     int n_variants;
00064     struct variant **variants;
00065     int cur_seq_no;
00066     URLContext *seg_hd;
00067     int64_t last_load_time;
00068 } AppleHTTPContext;
00069 
00070 static int read_chomp_line(AVIOContext *s, char *buf, int maxlen)
00071 {
00072     int len = ff_get_line(s, buf, maxlen);
00073     while (len > 0 && isspace(buf[len - 1]))
00074         buf[--len] = '\0';
00075     return len;
00076 }
00077 
00078 static void free_segment_list(AppleHTTPContext *s)
00079 {
00080     int i;
00081     for (i = 0; i < s->n_segments; i++)
00082         av_free(s->segments[i]);
00083     av_freep(&s->segments);
00084     s->n_segments = 0;
00085 }
00086 
00087 static void free_variant_list(AppleHTTPContext *s)
00088 {
00089     int i;
00090     for (i = 0; i < s->n_variants; i++)
00091         av_free(s->variants[i]);
00092     av_freep(&s->variants);
00093     s->n_variants = 0;
00094 }
00095 
00096 struct variant_info {
00097     char bandwidth[20];
00098 };
00099 
00100 static void handle_variant_args(struct variant_info *info, const char *key,
00101                                 int key_len, char **dest, int *dest_len)
00102 {
00103     if (!strncmp(key, "BANDWIDTH=", key_len)) {
00104         *dest     =        info->bandwidth;
00105         *dest_len = sizeof(info->bandwidth);
00106     }
00107 }
00108 
00109 static int parse_playlist(URLContext *h, const char *url)
00110 {
00111     AppleHTTPContext *s = h->priv_data;
00112     AVIOContext *in;
00113     int ret = 0, duration = 0, is_segment = 0, is_variant = 0, bandwidth = 0;
00114     char line[1024];
00115     const char *ptr;
00116 
00117     if ((ret = avio_open(&in, url, AVIO_RDONLY)) < 0)
00118         return ret;
00119 
00120     read_chomp_line(in, line, sizeof(line));
00121     if (strcmp(line, "#EXTM3U"))
00122         return AVERROR_INVALIDDATA;
00123 
00124     free_segment_list(s);
00125     s->finished = 0;
00126     while (!url_feof(in)) {
00127         read_chomp_line(in, line, sizeof(line));
00128         if (av_strstart(line, "#EXT-X-STREAM-INF:", &ptr)) {
00129             struct variant_info info = {{0}};
00130             is_variant = 1;
00131             ff_parse_key_value(ptr, (ff_parse_key_val_cb) handle_variant_args,
00132                                &info);
00133             bandwidth = atoi(info.bandwidth);
00134         } else if (av_strstart(line, "#EXT-X-TARGETDURATION:", &ptr)) {
00135             s->target_duration = atoi(ptr);
00136         } else if (av_strstart(line, "#EXT-X-MEDIA-SEQUENCE:", &ptr)) {
00137             s->start_seq_no = atoi(ptr);
00138         } else if (av_strstart(line, "#EXT-X-ENDLIST", &ptr)) {
00139             s->finished = 1;
00140         } else if (av_strstart(line, "#EXTINF:", &ptr)) {
00141             is_segment = 1;
00142             duration = atoi(ptr);
00143         } else if (av_strstart(line, "#", NULL)) {
00144             continue;
00145         } else if (line[0]) {
00146             if (is_segment) {
00147                 struct segment *seg = av_malloc(sizeof(struct segment));
00148                 if (!seg) {
00149                     ret = AVERROR(ENOMEM);
00150                     goto fail;
00151                 }
00152                 seg->duration = duration;
00153                 ff_make_absolute_url(seg->url, sizeof(seg->url), url, line);
00154                 dynarray_add(&s->segments, &s->n_segments, seg);
00155                 is_segment = 0;
00156             } else if (is_variant) {
00157                 struct variant *var = av_malloc(sizeof(struct variant));
00158                 if (!var) {
00159                     ret = AVERROR(ENOMEM);
00160                     goto fail;
00161                 }
00162                 var->bandwidth = bandwidth;
00163                 ff_make_absolute_url(var->url, sizeof(var->url), url, line);
00164                 dynarray_add(&s->variants, &s->n_variants, var);
00165                 is_variant = 0;
00166             }
00167         }
00168     }
00169     s->last_load_time = av_gettime();
00170 
00171 fail:
00172     avio_close(in);
00173     return ret;
00174 }
00175 
00176 static int applehttp_open(URLContext *h, const char *uri, int flags)
00177 {
00178     AppleHTTPContext *s;
00179     int ret, i;
00180     const char *nested_url;
00181 
00182     if (flags & (AVIO_WRONLY | AVIO_RDWR))
00183         return AVERROR(ENOSYS);
00184 
00185     s = av_mallocz(sizeof(AppleHTTPContext));
00186     if (!s)
00187         return AVERROR(ENOMEM);
00188     h->priv_data = s;
00189     h->is_streamed = 1;
00190 
00191     if (av_strstart(uri, "applehttp+", &nested_url)) {
00192         av_strlcpy(s->playlisturl, nested_url, sizeof(s->playlisturl));
00193     } else if (av_strstart(uri, "applehttp://", &nested_url)) {
00194         av_strlcpy(s->playlisturl, "http://", sizeof(s->playlisturl));
00195         av_strlcat(s->playlisturl, nested_url, sizeof(s->playlisturl));
00196     } else {
00197         av_log(NULL, AV_LOG_ERROR, "Unsupported url %s\n", uri);
00198         ret = AVERROR(EINVAL);
00199         goto fail;
00200     }
00201 
00202     if ((ret = parse_playlist(h, s->playlisturl)) < 0)
00203         goto fail;
00204 
00205     if (s->n_segments == 0 && s->n_variants > 0) {
00206         int max_bandwidth = 0, maxvar = -1;
00207         for (i = 0; i < s->n_variants; i++) {
00208             if (s->variants[i]->bandwidth > max_bandwidth || i == 0) {
00209                 max_bandwidth = s->variants[i]->bandwidth;
00210                 maxvar = i;
00211             }
00212         }
00213         av_strlcpy(s->playlisturl, s->variants[maxvar]->url,
00214                    sizeof(s->playlisturl));
00215         if ((ret = parse_playlist(h, s->playlisturl)) < 0)
00216             goto fail;
00217     }
00218 
00219     if (s->n_segments == 0) {
00220         av_log(NULL, AV_LOG_WARNING, "Empty playlist\n");
00221         ret = AVERROR(EIO);
00222         goto fail;
00223     }
00224     s->cur_seq_no = s->start_seq_no;
00225     if (!s->finished && s->n_segments >= 3)
00226         s->cur_seq_no = s->start_seq_no + s->n_segments - 3;
00227 
00228     return 0;
00229 
00230 fail:
00231     av_free(s);
00232     return ret;
00233 }
00234 
00235 static int applehttp_read(URLContext *h, uint8_t *buf, int size)
00236 {
00237     AppleHTTPContext *s = h->priv_data;
00238     const char *url;
00239     int ret;
00240 
00241 start:
00242     if (s->seg_hd) {
00243         ret = ffurl_read(s->seg_hd, buf, size);
00244         if (ret > 0)
00245             return ret;
00246     }
00247     if (s->seg_hd) {
00248         ffurl_close(s->seg_hd);
00249         s->seg_hd = NULL;
00250         s->cur_seq_no++;
00251     }
00252 retry:
00253     if (!s->finished) {
00254         int64_t now = av_gettime();
00255         if (now - s->last_load_time >= s->target_duration*1000000)
00256             if ((ret = parse_playlist(h, s->playlisturl)) < 0)
00257                 return ret;
00258     }
00259     if (s->cur_seq_no < s->start_seq_no) {
00260         av_log(NULL, AV_LOG_WARNING,
00261                "skipping %d segments ahead, expired from playlist\n",
00262                s->start_seq_no - s->cur_seq_no);
00263         s->cur_seq_no = s->start_seq_no;
00264     }
00265     if (s->cur_seq_no - s->start_seq_no >= s->n_segments) {
00266         if (s->finished)
00267             return AVERROR_EOF;
00268         while (av_gettime() - s->last_load_time < s->target_duration*1000000) {
00269             if (url_interrupt_cb())
00270                 return AVERROR_EXIT;
00271             usleep(100*1000);
00272         }
00273         goto retry;
00274     }
00275     url = s->segments[s->cur_seq_no - s->start_seq_no]->url,
00276     av_log(NULL, AV_LOG_DEBUG, "opening %s\n", url);
00277     ret = ffurl_open(&s->seg_hd, url, AVIO_RDONLY);
00278     if (ret < 0) {
00279         if (url_interrupt_cb())
00280             return AVERROR_EXIT;
00281         av_log(NULL, AV_LOG_WARNING, "Unable to open %s\n", url);
00282         s->cur_seq_no++;
00283         goto retry;
00284     }
00285     goto start;
00286 }
00287 
00288 static int applehttp_close(URLContext *h)
00289 {
00290     AppleHTTPContext *s = h->priv_data;
00291 
00292     free_segment_list(s);
00293     free_variant_list(s);
00294     ffurl_close(s->seg_hd);
00295     av_free(s);
00296     return 0;
00297 }
00298 
00299 URLProtocol ff_applehttp_protocol = {
00300     .name      = "applehttp",
00301     .url_open  = applehttp_open,
00302     .url_read  = applehttp_read,
00303     .url_close = applehttp_close,
00304     .flags     = URL_PROTOCOL_FLAG_NESTED_SCHEME,
00305 };

Generated on Fri Feb 22 2013 07:24:31 for FFmpeg by  doxygen 1.7.1