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ffmpeg / libavformat / applehttpproto.c @ 66e5b1df

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/*
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 * Apple HTTP Live Streaming Protocol Handler
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 * Copyright (c) 2010 Martin Storsjo
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 *
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 * This file is part of FFmpeg.
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 *
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 * FFmpeg is free software; you can redistribute it and/or
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 * modify it under the terms of the GNU Lesser General Public
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 * License as published by the Free Software Foundation; either
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 * version 2.1 of the License, or (at your option) any later version.
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 *
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 * FFmpeg is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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 * Lesser General Public License for more details.
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 *
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 * You should have received a copy of the GNU Lesser General Public
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 * License along with FFmpeg; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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 */
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/**
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 * @file
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 * Apple HTTP Live Streaming Protocol Handler
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 * http://tools.ietf.org/html/draft-pantos-http-live-streaming
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 */
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#define _XOPEN_SOURCE 600
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#include "libavutil/avstring.h"
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#include "avformat.h"
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#include "internal.h"
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#include <unistd.h>
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/*
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 * An apple http stream consists of a playlist with media segment files,
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 * played sequentially. There may be several playlists with the same
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 * video content, in different bandwidth variants, that are played in
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 * parallel (preferrably only one bandwidth variant at a time). In this case,
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 * the user supplied the url to a main playlist that only lists the variant
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 * playlists.
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 *
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 * If the main playlist doesn't point at any variants, we still create
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 * one anonymous toplevel variant for this, to maintain the structure.
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 */
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struct segment {
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    int duration;
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    char url[MAX_URL_SIZE];
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};
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struct variant {
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    int bandwidth;
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    char url[MAX_URL_SIZE];
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};
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typedef struct AppleHTTPContext {
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    char playlisturl[MAX_URL_SIZE];
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    int target_duration;
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    int start_seq_no;
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    int finished;
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    int n_segments;
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    struct segment **segments;
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    int n_variants;
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    struct variant **variants;
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    int cur_seq_no;
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    URLContext *seg_hd;
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    int64_t last_load_time;
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} AppleHTTPContext;
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static int read_chomp_line(AVIOContext *s, char *buf, int maxlen)
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{
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    int len = ff_get_line(s, buf, maxlen);
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    while (len > 0 && isspace(buf[len - 1]))
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        buf[--len] = '\0';
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    return len;
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}
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static void make_absolute_url(char *buf, int size, const char *base,
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                              const char *rel)
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{
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    char *sep;
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    /* Absolute path, relative to the current server */
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    if (base && strstr(base, "://") && rel[0] == '/') {
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        if (base != buf)
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            av_strlcpy(buf, base, size);
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        sep = strstr(buf, "://");
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        if (sep) {
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            sep += 3;
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            sep = strchr(sep, '/');
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            if (sep)
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                *sep = '\0';
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        }
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        av_strlcat(buf, rel, size);
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        return;
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    }
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    /* If rel actually is an absolute url, just copy it */
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    if (!base || strstr(rel, "://") || rel[0] == '/') {
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        av_strlcpy(buf, rel, size);
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        return;
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    }
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    if (base != buf)
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        av_strlcpy(buf, base, size);
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    /* Remove the file name from the base url */
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    sep = strrchr(buf, '/');
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    if (sep)
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        sep[1] = '\0';
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    else
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        buf[0] = '\0';
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    while (av_strstart(rel, "../", NULL) && sep) {
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        /* Remove the path delimiter at the end */
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        sep[0] = '\0';
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        sep = strrchr(buf, '/');
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        /* If the next directory name to pop off is "..", break here */
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        if (!strcmp(sep ? &sep[1] : buf, "..")) {
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            /* Readd the slash we just removed */
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            av_strlcat(buf, "/", size);
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            break;
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        }
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        /* Cut off the directory name */
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        if (sep)
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            sep[1] = '\0';
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        else
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            buf[0] = '\0';
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        rel += 3;
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    }
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    av_strlcat(buf, rel, size);
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}
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static void free_segment_list(AppleHTTPContext *s)
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{
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    int i;
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    for (i = 0; i < s->n_segments; i++)
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        av_free(s->segments[i]);
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    av_freep(&s->segments);
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    s->n_segments = 0;
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}
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static void free_variant_list(AppleHTTPContext *s)
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{
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    int i;
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    for (i = 0; i < s->n_variants; i++)
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        av_free(s->variants[i]);
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    av_freep(&s->variants);
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    s->n_variants = 0;
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}
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struct variant_info {
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    char bandwidth[20];
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};
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static void handle_variant_args(struct variant_info *info, const char *key,
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                                int key_len, char **dest, int *dest_len)
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{
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    if (!strncmp(key, "BANDWIDTH=", key_len)) {
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        *dest     =        info->bandwidth;
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        *dest_len = sizeof(info->bandwidth);
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    }
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}
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static int parse_playlist(URLContext *h, const char *url)
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{
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    AppleHTTPContext *s = h->priv_data;
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    AVIOContext *in;
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    int ret = 0, duration = 0, is_segment = 0, is_variant = 0, bandwidth = 0;
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    char line[1024];
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    const char *ptr;
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    if ((ret = avio_open(&in, url, URL_RDONLY)) < 0)
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        return ret;
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    read_chomp_line(in, line, sizeof(line));
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    if (strcmp(line, "#EXTM3U"))
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        return AVERROR_INVALIDDATA;
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    free_segment_list(s);
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    s->finished = 0;
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    while (!in->eof_reached) {
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        read_chomp_line(in, line, sizeof(line));
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        if (av_strstart(line, "#EXT-X-STREAM-INF:", &ptr)) {
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            struct variant_info info = {{0}};
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            is_variant = 1;
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            ff_parse_key_value(ptr, (ff_parse_key_val_cb) handle_variant_args,
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                               &info);
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            bandwidth = atoi(info.bandwidth);
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        } else if (av_strstart(line, "#EXT-X-TARGETDURATION:", &ptr)) {
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            s->target_duration = atoi(ptr);
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        } else if (av_strstart(line, "#EXT-X-MEDIA-SEQUENCE:", &ptr)) {
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            s->start_seq_no = atoi(ptr);
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        } else if (av_strstart(line, "#EXT-X-ENDLIST", &ptr)) {
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            s->finished = 1;
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        } else if (av_strstart(line, "#EXTINF:", &ptr)) {
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            is_segment = 1;
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            duration = atoi(ptr);
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        } else if (av_strstart(line, "#", NULL)) {
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            continue;
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        } else if (line[0]) {
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            if (is_segment) {
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                struct segment *seg = av_malloc(sizeof(struct segment));
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                if (!seg) {
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                    ret = AVERROR(ENOMEM);
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                    goto fail;
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                }
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                seg->duration = duration;
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                make_absolute_url(seg->url, sizeof(seg->url), url, line);
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                dynarray_add(&s->segments, &s->n_segments, seg);
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                is_segment = 0;
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            } else if (is_variant) {
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                struct variant *var = av_malloc(sizeof(struct variant));
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                if (!var) {
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                    ret = AVERROR(ENOMEM);
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                    goto fail;
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                }
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                var->bandwidth = bandwidth;
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                make_absolute_url(var->url, sizeof(var->url), url, line);
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                dynarray_add(&s->variants, &s->n_variants, var);
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                is_variant = 0;
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            }
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        }
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    }
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    s->last_load_time = av_gettime();
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fail:
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    avio_close(in);
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    return ret;
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}
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static int applehttp_open(URLContext *h, const char *uri, int flags)
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{
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    AppleHTTPContext *s;
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    int ret, i;
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    const char *nested_url;
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    if (flags & (URL_WRONLY | URL_RDWR))
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        return AVERROR_NOTSUPP;
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    s = av_mallocz(sizeof(AppleHTTPContext));
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    if (!s)
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        return AVERROR(ENOMEM);
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    h->priv_data = s;
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    h->is_streamed = 1;
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    if (av_strstart(uri, "applehttp+", &nested_url)) {
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        av_strlcpy(s->playlisturl, nested_url, sizeof(s->playlisturl));
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    } else if (av_strstart(uri, "applehttp://", &nested_url)) {
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        av_strlcpy(s->playlisturl, "http://", sizeof(s->playlisturl));
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        av_strlcat(s->playlisturl, nested_url, sizeof(s->playlisturl));
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    } else {
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        av_log(NULL, AV_LOG_ERROR, "Unsupported url %s\n", uri);
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        ret = AVERROR(EINVAL);
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        goto fail;
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    }
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    if ((ret = parse_playlist(h, s->playlisturl)) < 0)
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        goto fail;
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    if (s->n_segments == 0 && s->n_variants > 0) {
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        int max_bandwidth = 0, maxvar = -1;
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        for (i = 0; i < s->n_variants; i++) {
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            if (s->variants[i]->bandwidth > max_bandwidth || i == 0) {
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                max_bandwidth = s->variants[i]->bandwidth;
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                maxvar = i;
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            }
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        }
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        av_strlcpy(s->playlisturl, s->variants[maxvar]->url,
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                   sizeof(s->playlisturl));
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        if ((ret = parse_playlist(h, s->playlisturl)) < 0)
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            goto fail;
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    }
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    if (s->n_segments == 0) {
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        av_log(NULL, AV_LOG_WARNING, "Empty playlist\n");
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        ret = AVERROR(EIO);
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        goto fail;
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    }
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    s->cur_seq_no = s->start_seq_no;
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    if (!s->finished && s->n_segments >= 3)
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        s->cur_seq_no = s->start_seq_no + s->n_segments - 3;
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    return 0;
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fail:
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    av_free(s);
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    return ret;
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}
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static int applehttp_read(URLContext *h, uint8_t *buf, int size)
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{
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    AppleHTTPContext *s = h->priv_data;
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    const char *url;
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    int ret;
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start:
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    if (s->seg_hd) {
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        ret = url_read(s->seg_hd, buf, size);
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        if (ret > 0)
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            return ret;
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    }
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    if (s->seg_hd) {
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        url_close(s->seg_hd);
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        s->seg_hd = NULL;
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        s->cur_seq_no++;
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    }
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retry:
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    if (!s->finished) {
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        int64_t now = av_gettime();
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        if (now - s->last_load_time >= s->target_duration*1000000)
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            if ((ret = parse_playlist(h, s->playlisturl)) < 0)
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                return ret;
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    }
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    if (s->cur_seq_no < s->start_seq_no) {
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        av_log(NULL, AV_LOG_WARNING,
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               "skipping %d segments ahead, expired from playlist\n",
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               s->start_seq_no - s->cur_seq_no);
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        s->cur_seq_no = s->start_seq_no;
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    }
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    if (s->cur_seq_no - s->start_seq_no >= s->n_segments) {
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        if (s->finished)
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            return AVERROR_EOF;
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        while (av_gettime() - s->last_load_time < s->target_duration*1000000) {
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            if (url_interrupt_cb())
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                return AVERROR(EINTR);
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            usleep(100*1000);
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        }
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        goto retry;
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    }
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    url = s->segments[s->cur_seq_no - s->start_seq_no]->url,
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    av_log(NULL, AV_LOG_DEBUG, "opening %s\n", url);
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    ret = url_open(&s->seg_hd, url, URL_RDONLY);
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    if (ret < 0) {
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        if (url_interrupt_cb())
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            return AVERROR(EINTR);
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        av_log(NULL, AV_LOG_WARNING, "Unable to open %s\n", url);
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        s->cur_seq_no++;
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        goto retry;
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    }
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    goto start;
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}
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static int applehttp_close(URLContext *h)
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{
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    AppleHTTPContext *s = h->priv_data;
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    free_segment_list(s);
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    free_variant_list(s);
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    url_close(s->seg_hd);
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    av_free(s);
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    return 0;
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}
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URLProtocol ff_applehttp_protocol = {
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    "applehttp",
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    applehttp_open,
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    applehttp_read,
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    NULL, /* write */
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    NULL, /* seek */
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    applehttp_close,
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    .flags = URL_PROTOCOL_FLAG_NESTED_SCHEME,
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};