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libavformat/applehttp.c

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00001 /*
00002  * Apple HTTP Live Streaming demuxer
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 "libavutil/intreadwrite.h"
00030 #include "libavutil/mathematics.h"
00031 #include "libavutil/opt.h"
00032 #include "libavutil/dict.h"
00033 #include "avformat.h"
00034 #include "internal.h"
00035 #include <unistd.h>
00036 #include "avio_internal.h"
00037 #include "url.h"
00038 
00039 #define INITIAL_BUFFER_SIZE 32768
00040 
00041 /*
00042  * An apple http stream consists of a playlist with media segment files,
00043  * played sequentially. There may be several playlists with the same
00044  * video content, in different bandwidth variants, that are played in
00045  * parallel (preferrably only one bandwidth variant at a time). In this case,
00046  * the user supplied the url to a main playlist that only lists the variant
00047  * playlists.
00048  *
00049  * If the main playlist doesn't point at any variants, we still create
00050  * one anonymous toplevel variant for this, to maintain the structure.
00051  */
00052 
00053 enum KeyType {
00054     KEY_NONE,
00055     KEY_AES_128,
00056 };
00057 
00058 struct segment {
00059     int duration;
00060     char url[MAX_URL_SIZE];
00061     char key[MAX_URL_SIZE];
00062     enum KeyType key_type;
00063     uint8_t iv[16];
00064 };
00065 
00066 /*
00067  * Each variant has its own demuxer. If it currently is active,
00068  * it has an open AVIOContext too, and potentially an AVPacket
00069  * containing the next packet from this stream.
00070  */
00071 struct variant {
00072     int bandwidth;
00073     char url[MAX_URL_SIZE];
00074     AVIOContext pb;
00075     uint8_t* read_buffer;
00076     URLContext *input;
00077     AVFormatContext *parent;
00078     int index;
00079     AVFormatContext *ctx;
00080     AVPacket pkt;
00081     int stream_offset;
00082 
00083     int finished;
00084     int target_duration;
00085     int start_seq_no;
00086     int n_segments;
00087     struct segment **segments;
00088     int needed, cur_needed;
00089     int cur_seq_no;
00090     int64_t last_load_time;
00091 
00092     char key_url[MAX_URL_SIZE];
00093     uint8_t key[16];
00094 };
00095 
00096 typedef struct AppleHTTPContext {
00097     int n_variants;
00098     struct variant **variants;
00099     int cur_seq_no;
00100     int end_of_segment;
00101     int first_packet;
00102     int64_t first_timestamp;
00103     int64_t seek_timestamp;
00104     int seek_flags;
00105     AVIOInterruptCB *interrupt_callback;
00106 } AppleHTTPContext;
00107 
00108 static int read_chomp_line(AVIOContext *s, char *buf, int maxlen)
00109 {
00110     int len = ff_get_line(s, buf, maxlen);
00111     while (len > 0 && isspace(buf[len - 1]))
00112         buf[--len] = '\0';
00113     return len;
00114 }
00115 
00116 static void free_segment_list(struct variant *var)
00117 {
00118     int i;
00119     for (i = 0; i < var->n_segments; i++)
00120         av_free(var->segments[i]);
00121     av_freep(&var->segments);
00122     var->n_segments = 0;
00123 }
00124 
00125 static void free_variant_list(AppleHTTPContext *c)
00126 {
00127     int i;
00128     for (i = 0; i < c->n_variants; i++) {
00129         struct variant *var = c->variants[i];
00130         free_segment_list(var);
00131         av_free_packet(&var->pkt);
00132         av_free(var->pb.buffer);
00133         if (var->input)
00134             ffurl_close(var->input);
00135         if (var->ctx) {
00136             var->ctx->pb = NULL;
00137             avformat_close_input(&var->ctx);
00138         }
00139         av_free(var);
00140     }
00141     av_freep(&c->variants);
00142     c->n_variants = 0;
00143 }
00144 
00145 /*
00146  * Used to reset a statically allocated AVPacket to a clean slate,
00147  * containing no data.
00148  */
00149 static void reset_packet(AVPacket *pkt)
00150 {
00151     av_init_packet(pkt);
00152     pkt->data = NULL;
00153 }
00154 
00155 static struct variant *new_variant(AppleHTTPContext *c, int bandwidth,
00156                                    const char *url, const char *base)
00157 {
00158     struct variant *var = av_mallocz(sizeof(struct variant));
00159     if (!var)
00160         return NULL;
00161     reset_packet(&var->pkt);
00162     var->bandwidth = bandwidth;
00163     ff_make_absolute_url(var->url, sizeof(var->url), base, url);
00164     dynarray_add(&c->variants, &c->n_variants, var);
00165     return var;
00166 }
00167 
00168 struct variant_info {
00169     char bandwidth[20];
00170 };
00171 
00172 static void handle_variant_args(struct variant_info *info, const char *key,
00173                                 int key_len, char **dest, int *dest_len)
00174 {
00175     if (!strncmp(key, "BANDWIDTH=", key_len)) {
00176         *dest     =        info->bandwidth;
00177         *dest_len = sizeof(info->bandwidth);
00178     }
00179 }
00180 
00181 struct key_info {
00182      char uri[MAX_URL_SIZE];
00183      char method[10];
00184      char iv[35];
00185 };
00186 
00187 static void handle_key_args(struct key_info *info, const char *key,
00188                             int key_len, char **dest, int *dest_len)
00189 {
00190     if (!strncmp(key, "METHOD=", key_len)) {
00191         *dest     =        info->method;
00192         *dest_len = sizeof(info->method);
00193     } else if (!strncmp(key, "URI=", key_len)) {
00194         *dest     =        info->uri;
00195         *dest_len = sizeof(info->uri);
00196     } else if (!strncmp(key, "IV=", key_len)) {
00197         *dest     =        info->iv;
00198         *dest_len = sizeof(info->iv);
00199     }
00200 }
00201 
00202 static int parse_playlist(AppleHTTPContext *c, const char *url,
00203                           struct variant *var, AVIOContext *in)
00204 {
00205     int ret = 0, duration = 0, is_segment = 0, is_variant = 0, bandwidth = 0;
00206     enum KeyType key_type = KEY_NONE;
00207     uint8_t iv[16] = "";
00208     int has_iv = 0;
00209     char key[MAX_URL_SIZE] = "";
00210     char line[1024];
00211     const char *ptr;
00212     int close_in = 0;
00213 
00214     if (!in) {
00215         close_in = 1;
00216         if ((ret = avio_open2(&in, url, AVIO_FLAG_READ,
00217                               c->interrupt_callback, NULL)) < 0)
00218             return ret;
00219     }
00220 
00221     read_chomp_line(in, line, sizeof(line));
00222     if (strcmp(line, "#EXTM3U")) {
00223         ret = AVERROR_INVALIDDATA;
00224         goto fail;
00225     }
00226 
00227     if (var) {
00228         free_segment_list(var);
00229         var->finished = 0;
00230     }
00231     while (!url_feof(in)) {
00232         read_chomp_line(in, line, sizeof(line));
00233         if (av_strstart(line, "#EXT-X-STREAM-INF:", &ptr)) {
00234             struct variant_info info = {{0}};
00235             is_variant = 1;
00236             ff_parse_key_value(ptr, (ff_parse_key_val_cb) handle_variant_args,
00237                                &info);
00238             bandwidth = atoi(info.bandwidth);
00239         } else if (av_strstart(line, "#EXT-X-KEY:", &ptr)) {
00240             struct key_info info = {{0}};
00241             ff_parse_key_value(ptr, (ff_parse_key_val_cb) handle_key_args,
00242                                &info);
00243             key_type = KEY_NONE;
00244             has_iv = 0;
00245             if (!strcmp(info.method, "AES-128"))
00246                 key_type = KEY_AES_128;
00247             if (!strncmp(info.iv, "0x", 2) || !strncmp(info.iv, "0X", 2)) {
00248                 ff_hex_to_data(iv, info.iv + 2);
00249                 has_iv = 1;
00250             }
00251             av_strlcpy(key, info.uri, sizeof(key));
00252         } else if (av_strstart(line, "#EXT-X-TARGETDURATION:", &ptr)) {
00253             if (!var) {
00254                 var = new_variant(c, 0, url, NULL);
00255                 if (!var) {
00256                     ret = AVERROR(ENOMEM);
00257                     goto fail;
00258                 }
00259             }
00260             var->target_duration = atoi(ptr);
00261         } else if (av_strstart(line, "#EXT-X-MEDIA-SEQUENCE:", &ptr)) {
00262             if (!var) {
00263                 var = new_variant(c, 0, url, NULL);
00264                 if (!var) {
00265                     ret = AVERROR(ENOMEM);
00266                     goto fail;
00267                 }
00268             }
00269             var->start_seq_no = atoi(ptr);
00270         } else if (av_strstart(line, "#EXT-X-ENDLIST", &ptr)) {
00271             if (var)
00272                 var->finished = 1;
00273         } else if (av_strstart(line, "#EXTINF:", &ptr)) {
00274             is_segment = 1;
00275             duration   = atoi(ptr);
00276         } else if (av_strstart(line, "#", NULL)) {
00277             continue;
00278         } else if (line[0]) {
00279             if (is_variant) {
00280                 if (!new_variant(c, bandwidth, line, url)) {
00281                     ret = AVERROR(ENOMEM);
00282                     goto fail;
00283                 }
00284                 is_variant = 0;
00285                 bandwidth  = 0;
00286             }
00287             if (is_segment) {
00288                 struct segment *seg;
00289                 if (!var) {
00290                     var = new_variant(c, 0, url, NULL);
00291                     if (!var) {
00292                         ret = AVERROR(ENOMEM);
00293                         goto fail;
00294                     }
00295                 }
00296                 seg = av_malloc(sizeof(struct segment));
00297                 if (!seg) {
00298                     ret = AVERROR(ENOMEM);
00299                     goto fail;
00300                 }
00301                 seg->duration = duration;
00302                 seg->key_type = key_type;
00303                 if (has_iv) {
00304                     memcpy(seg->iv, iv, sizeof(iv));
00305                 } else {
00306                     int seq = var->start_seq_no + var->n_segments;
00307                     memset(seg->iv, 0, sizeof(seg->iv));
00308                     AV_WB32(seg->iv + 12, seq);
00309                 }
00310                 ff_make_absolute_url(seg->key, sizeof(seg->key), url, key);
00311                 ff_make_absolute_url(seg->url, sizeof(seg->url), url, line);
00312                 dynarray_add(&var->segments, &var->n_segments, seg);
00313                 is_segment = 0;
00314             }
00315         }
00316     }
00317     if (var)
00318         var->last_load_time = av_gettime();
00319 
00320 fail:
00321     if (close_in)
00322         avio_close(in);
00323     return ret;
00324 }
00325 
00326 static int open_input(struct variant *var)
00327 {
00328     struct segment *seg = var->segments[var->cur_seq_no - var->start_seq_no];
00329     if (seg->key_type == KEY_NONE) {
00330         return ffurl_open(&var->input, seg->url, AVIO_FLAG_READ,
00331                           &var->parent->interrupt_callback, NULL);
00332     } else if (seg->key_type == KEY_AES_128) {
00333         char iv[33], key[33], url[MAX_URL_SIZE];
00334         int ret;
00335         if (strcmp(seg->key, var->key_url)) {
00336             URLContext *uc;
00337             if (ffurl_open(&uc, seg->key, AVIO_FLAG_READ,
00338                            &var->parent->interrupt_callback, NULL) == 0) {
00339                 if (ffurl_read_complete(uc, var->key, sizeof(var->key))
00340                     != sizeof(var->key)) {
00341                     av_log(NULL, AV_LOG_ERROR, "Unable to read key file %s\n",
00342                            seg->key);
00343                 }
00344                 ffurl_close(uc);
00345             } else {
00346                 av_log(NULL, AV_LOG_ERROR, "Unable to open key file %s\n",
00347                        seg->key);
00348             }
00349             av_strlcpy(var->key_url, seg->key, sizeof(var->key_url));
00350         }
00351         ff_data_to_hex(iv, seg->iv, sizeof(seg->iv), 0);
00352         ff_data_to_hex(key, var->key, sizeof(var->key), 0);
00353         iv[32] = key[32] = '\0';
00354         if (strstr(seg->url, "://"))
00355             snprintf(url, sizeof(url), "crypto+%s", seg->url);
00356         else
00357             snprintf(url, sizeof(url), "crypto:%s", seg->url);
00358         if ((ret = ffurl_alloc(&var->input, url, AVIO_FLAG_READ,
00359                                &var->parent->interrupt_callback)) < 0)
00360             return ret;
00361         av_opt_set(var->input->priv_data, "key", key, 0);
00362         av_opt_set(var->input->priv_data, "iv", iv, 0);
00363         if ((ret = ffurl_connect(var->input, NULL)) < 0) {
00364             ffurl_close(var->input);
00365             var->input = NULL;
00366             return ret;
00367         }
00368         return 0;
00369     }
00370     return AVERROR(ENOSYS);
00371 }
00372 
00373 static int read_data(void *opaque, uint8_t *buf, int buf_size)
00374 {
00375     struct variant *v = opaque;
00376     AppleHTTPContext *c = v->parent->priv_data;
00377     int ret, i;
00378 
00379 restart:
00380     if (!v->input) {
00381         /* If this is a live stream and the reload interval has elapsed since
00382          * the last playlist reload, reload the variant playlists now. */
00383         int64_t reload_interval = v->n_segments > 0 ?
00384                                   v->segments[v->n_segments - 1]->duration :
00385                                   v->target_duration;
00386         reload_interval *= 1000000;
00387 
00388 reload:
00389         if (!v->finished &&
00390             av_gettime() - v->last_load_time >= reload_interval) {
00391             if ((ret = parse_playlist(c, v->url, v, NULL)) < 0)
00392                 return ret;
00393             /* If we need to reload the playlist again below (if
00394              * there's still no more segments), switch to a reload
00395              * interval of half the target duration. */
00396             reload_interval = v->target_duration * 500000;
00397         }
00398         if (v->cur_seq_no < v->start_seq_no) {
00399             av_log(NULL, AV_LOG_WARNING,
00400                    "skipping %d segments ahead, expired from playlists\n",
00401                    v->start_seq_no - v->cur_seq_no);
00402             v->cur_seq_no = v->start_seq_no;
00403         }
00404         if (v->cur_seq_no >= v->start_seq_no + v->n_segments) {
00405             if (v->finished)
00406                 return AVERROR_EOF;
00407             while (av_gettime() - v->last_load_time < reload_interval) {
00408                 if (ff_check_interrupt(c->interrupt_callback))
00409                     return AVERROR_EXIT;
00410                 usleep(100*1000);
00411             }
00412             /* Enough time has elapsed since the last reload */
00413             goto reload;
00414         }
00415 
00416         ret = open_input(v);
00417         if (ret < 0)
00418             return ret;
00419     }
00420     ret = ffurl_read(v->input, buf, buf_size);
00421     if (ret > 0)
00422         return ret;
00423     if (ret < 0 && ret != AVERROR_EOF)
00424         return ret;
00425     ffurl_close(v->input);
00426     v->input = NULL;
00427     v->cur_seq_no++;
00428 
00429     c->end_of_segment = 1;
00430     c->cur_seq_no = v->cur_seq_no;
00431 
00432     if (v->ctx && v->ctx->nb_streams) {
00433         v->needed = 0;
00434         for (i = v->stream_offset; i < v->stream_offset + v->ctx->nb_streams;
00435              i++) {
00436             if (v->parent->streams[i]->discard < AVDISCARD_ALL)
00437                 v->needed = 1;
00438         }
00439     }
00440     if (!v->needed) {
00441         av_log(v->parent, AV_LOG_INFO, "No longer receiving variant %d\n",
00442                v->index);
00443         return AVERROR_EOF;
00444     }
00445     goto restart;
00446 }
00447 
00448 static int applehttp_read_header(AVFormatContext *s, AVFormatParameters *ap)
00449 {
00450     AppleHTTPContext *c = s->priv_data;
00451     int ret = 0, i, j, stream_offset = 0;
00452 
00453     c->interrupt_callback = &s->interrupt_callback;
00454 
00455     if ((ret = parse_playlist(c, s->filename, NULL, s->pb)) < 0)
00456         goto fail;
00457 
00458     if (c->n_variants == 0) {
00459         av_log(NULL, AV_LOG_WARNING, "Empty playlist\n");
00460         ret = AVERROR_EOF;
00461         goto fail;
00462     }
00463     /* If the playlist only contained variants, parse each individual
00464      * variant playlist. */
00465     if (c->n_variants > 1 || c->variants[0]->n_segments == 0) {
00466         for (i = 0; i < c->n_variants; i++) {
00467             struct variant *v = c->variants[i];
00468             if ((ret = parse_playlist(c, v->url, v, NULL)) < 0)
00469                 goto fail;
00470         }
00471     }
00472 
00473     if (c->variants[0]->n_segments == 0) {
00474         av_log(NULL, AV_LOG_WARNING, "Empty playlist\n");
00475         ret = AVERROR_EOF;
00476         goto fail;
00477     }
00478 
00479     /* If this isn't a live stream, calculate the total duration of the
00480      * stream. */
00481     if (c->variants[0]->finished) {
00482         int64_t duration = 0;
00483         for (i = 0; i < c->variants[0]->n_segments; i++)
00484             duration += c->variants[0]->segments[i]->duration;
00485         s->duration = duration * AV_TIME_BASE;
00486     }
00487 
00488     /* Open the demuxer for each variant */
00489     for (i = 0; i < c->n_variants; i++) {
00490         struct variant *v = c->variants[i];
00491         AVInputFormat *in_fmt = NULL;
00492         char bitrate_str[20];
00493         if (v->n_segments == 0)
00494             continue;
00495 
00496         if (!(v->ctx = avformat_alloc_context())) {
00497             ret = AVERROR(ENOMEM);
00498             goto fail;
00499         }
00500 
00501         v->index  = i;
00502         v->needed = 1;
00503         v->parent = s;
00504 
00505         /* If this is a live stream with more than 3 segments, start at the
00506          * third last segment. */
00507         v->cur_seq_no = v->start_seq_no;
00508         if (!v->finished && v->n_segments > 3)
00509             v->cur_seq_no = v->start_seq_no + v->n_segments - 3;
00510 
00511         v->read_buffer = av_malloc(INITIAL_BUFFER_SIZE);
00512         ffio_init_context(&v->pb, v->read_buffer, INITIAL_BUFFER_SIZE, 0, v,
00513                           read_data, NULL, NULL);
00514         v->pb.seekable = 0;
00515         ret = av_probe_input_buffer(&v->pb, &in_fmt, v->segments[0]->url,
00516                                     NULL, 0, 0);
00517         if (ret < 0) {
00518             /* Free the ctx - it isn't initialized properly at this point,
00519              * so avformat_close_input shouldn't be called. If
00520              * avformat_open_input fails below, it frees and zeros the
00521              * context, so it doesn't need any special treatment like this. */
00522             avformat_free_context(v->ctx);
00523             v->ctx = NULL;
00524             goto fail;
00525         }
00526         v->ctx->pb       = &v->pb;
00527         ret = avformat_open_input(&v->ctx, v->segments[0]->url, in_fmt, NULL);
00528         if (ret < 0)
00529             goto fail;
00530         v->stream_offset = stream_offset;
00531         snprintf(bitrate_str, sizeof(bitrate_str), "%d", v->bandwidth);
00532         /* Create new AVStreams for each stream in this variant */
00533         for (j = 0; j < v->ctx->nb_streams; j++) {
00534             AVStream *st = avformat_new_stream(s, NULL);
00535             if (!st) {
00536                 ret = AVERROR(ENOMEM);
00537                 goto fail;
00538             }
00539             st->id = i;
00540             avcodec_copy_context(st->codec, v->ctx->streams[j]->codec);
00541             if (v->bandwidth)
00542                 av_dict_set(&st->metadata, "variant_bitrate", bitrate_str,
00543                                  0);
00544         }
00545         stream_offset += v->ctx->nb_streams;
00546     }
00547 
00548     c->first_packet = 1;
00549     c->first_timestamp = AV_NOPTS_VALUE;
00550     c->seek_timestamp = AV_NOPTS_VALUE;
00551 
00552     return 0;
00553 fail:
00554     free_variant_list(c);
00555     return ret;
00556 }
00557 
00558 static int recheck_discard_flags(AVFormatContext *s, int first)
00559 {
00560     AppleHTTPContext *c = s->priv_data;
00561     int i, changed = 0;
00562 
00563     /* Check if any new streams are needed */
00564     for (i = 0; i < c->n_variants; i++)
00565         c->variants[i]->cur_needed = 0;
00566 
00567     for (i = 0; i < s->nb_streams; i++) {
00568         AVStream *st = s->streams[i];
00569         struct variant *var = c->variants[s->streams[i]->id];
00570         if (st->discard < AVDISCARD_ALL)
00571             var->cur_needed = 1;
00572     }
00573     for (i = 0; i < c->n_variants; i++) {
00574         struct variant *v = c->variants[i];
00575         if (v->cur_needed && !v->needed) {
00576             v->needed = 1;
00577             changed = 1;
00578             v->cur_seq_no = c->cur_seq_no;
00579             v->pb.eof_reached = 0;
00580             av_log(s, AV_LOG_INFO, "Now receiving variant %d\n", i);
00581         } else if (first && !v->cur_needed && v->needed) {
00582             if (v->input)
00583                 ffurl_close(v->input);
00584             v->input = NULL;
00585             v->needed = 0;
00586             changed = 1;
00587             av_log(s, AV_LOG_INFO, "No longer receiving variant %d\n", i);
00588         }
00589     }
00590     return changed;
00591 }
00592 
00593 static int applehttp_read_packet(AVFormatContext *s, AVPacket *pkt)
00594 {
00595     AppleHTTPContext *c = s->priv_data;
00596     int ret, i, minvariant = -1;
00597 
00598     if (c->first_packet) {
00599         recheck_discard_flags(s, 1);
00600         c->first_packet = 0;
00601     }
00602 
00603 start:
00604     c->end_of_segment = 0;
00605     for (i = 0; i < c->n_variants; i++) {
00606         struct variant *var = c->variants[i];
00607         /* Make sure we've got one buffered packet from each open variant
00608          * stream */
00609         if (var->needed && !var->pkt.data) {
00610             while (1) {
00611                 int64_t ts_diff;
00612                 ret = av_read_frame(var->ctx, &var->pkt);
00613                 if (ret < 0) {
00614                     if (!url_feof(&var->pb)) {
00615                         return ret;
00616                     } else {
00617                         if ((var->cur_seq_no - var->start_seq_no) == (var->n_segments)) {
00618                             return AVERROR_EOF;
00619                         }
00620                     }
00621                     reset_packet(&var->pkt);
00622                 } else {
00623                     if (c->first_timestamp == AV_NOPTS_VALUE)
00624                         c->first_timestamp = var->pkt.dts;
00625                 }
00626 
00627                 if (c->seek_timestamp == AV_NOPTS_VALUE)
00628                     break;
00629 
00630                 if (var->pkt.dts == AV_NOPTS_VALUE) {
00631                     c->seek_timestamp = AV_NOPTS_VALUE;
00632                     break;
00633                 }
00634 
00635                 ts_diff = var->pkt.dts - c->seek_timestamp;
00636                 if (ts_diff >= 0) {
00637                     if (c->seek_flags & AVSEEK_FLAG_ANY) {
00638                         c->seek_timestamp = AV_NOPTS_VALUE;
00639                         break;
00640                     }
00641 
00642                     /* Seek to keyframe */
00643                     if (var->pkt.flags & AV_PKT_FLAG_KEY) {
00644                         c->seek_timestamp = AV_NOPTS_VALUE;
00645                         break;
00646                     }
00647                 }
00648             }
00649         }
00650         /* Check if this stream has the packet with the lowest dts */
00651         if (var->pkt.data) {
00652             if (minvariant < 0 ||
00653                 var->pkt.dts < c->variants[minvariant]->pkt.dts)
00654                 minvariant = i;
00655         }
00656     }
00657     if (c->end_of_segment) {
00658         if (recheck_discard_flags(s, 0))
00659             goto start;
00660     }
00661     /* If we got a packet, return it */
00662     if (minvariant >= 0) {
00663         *pkt = c->variants[minvariant]->pkt;
00664         pkt->stream_index += c->variants[minvariant]->stream_offset;
00665         reset_packet(&c->variants[minvariant]->pkt);
00666         return 0;
00667     }
00668     return AVERROR_EOF;
00669 }
00670 
00671 static int applehttp_close(AVFormatContext *s)
00672 {
00673     AppleHTTPContext *c = s->priv_data;
00674 
00675     free_variant_list(c);
00676     return 0;
00677 }
00678 
00679 static int applehttp_read_seek(AVFormatContext *s, int stream_index,
00680                                int64_t timestamp, int flags)
00681 {
00682     AppleHTTPContext *c = s->priv_data;
00683     int i, j, ret;
00684 
00685     if ((flags & AVSEEK_FLAG_BYTE) || !c->variants[0]->finished)
00686         return AVERROR(ENOSYS);
00687 
00688     c->seek_timestamp = timestamp;
00689     c->seek_flags = flags;
00690     timestamp = av_rescale_rnd(timestamp, 1, stream_index >= 0 ?
00691                                s->streams[stream_index]->time_base.den :
00692                                AV_TIME_BASE, flags & AVSEEK_FLAG_BACKWARD ?
00693                                AV_ROUND_DOWN : AV_ROUND_UP);
00694     if (s->duration < c->seek_timestamp) {
00695         c->seek_timestamp = AV_NOPTS_VALUE;
00696         return AVERROR(EIO);
00697     }
00698 
00699     ret = AVERROR(EIO);
00700     for (i = 0; i < c->n_variants; i++) {
00701         /* Reset reading */
00702         struct variant *var = c->variants[i];
00703         int64_t pos = c->first_timestamp == AV_NOPTS_VALUE ? 0 :
00704                       av_rescale_rnd(c->first_timestamp, 1, stream_index >= 0 ?
00705                                s->streams[stream_index]->time_base.den :
00706                                AV_TIME_BASE, flags & AVSEEK_FLAG_BACKWARD ?
00707                                AV_ROUND_DOWN : AV_ROUND_UP);
00708          if (var->input) {
00709             ffurl_close(var->input);
00710             var->input = NULL;
00711         }
00712         av_free_packet(&var->pkt);
00713         reset_packet(&var->pkt);
00714         var->pb.eof_reached = 0;
00715 
00716         /* Locate the segment that contains the target timestamp */
00717         for (j = 0; j < var->n_segments; j++) {
00718             if (timestamp >= pos &&
00719                 timestamp < pos + var->segments[j]->duration) {
00720                 var->cur_seq_no = var->start_seq_no + j;
00721                 ret = 0;
00722                 break;
00723             }
00724             pos += var->segments[j]->duration;
00725         }
00726         if (ret != 0)
00727             c->seek_timestamp = AV_NOPTS_VALUE;
00728     }
00729     return ret;
00730 }
00731 
00732 static int applehttp_probe(AVProbeData *p)
00733 {
00734     /* Require #EXTM3U at the start, and either one of the ones below
00735      * somewhere for a proper match. */
00736     if (strncmp(p->buf, "#EXTM3U", 7))
00737         return 0;
00738     if (strstr(p->buf, "#EXT-X-STREAM-INF:")     ||
00739         strstr(p->buf, "#EXT-X-TARGETDURATION:") ||
00740         strstr(p->buf, "#EXT-X-MEDIA-SEQUENCE:"))
00741         return AVPROBE_SCORE_MAX;
00742     return 0;
00743 }
00744 
00745 AVInputFormat ff_applehttp_demuxer = {
00746     .name           = "applehttp",
00747     .long_name      = NULL_IF_CONFIG_SMALL("Apple HTTP Live Streaming format"),
00748     .priv_data_size = sizeof(AppleHTTPContext),
00749     .read_probe     = applehttp_probe,
00750     .read_header    = applehttp_read_header,
00751     .read_packet    = applehttp_read_packet,
00752     .read_close     = applehttp_close,
00753     .read_seek      = applehttp_read_seek,
00754 };
Generated on Fri Feb 1 2013 14:34:50 for FFmpeg by doxygen 1.7.1