2
* Apple HTTP Live Streaming demuxer
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* Copyright (c) 2010 Martin Storsjo
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* This file is part of Libav.
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* Libav 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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* Libav 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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* You should have received a copy of the GNU Lesser General Public
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* License along with Libav; 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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* Apple HTTP Live Streaming demuxer
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* http://tools.ietf.org/html/draft-pantos-http-live-streaming
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#include "libavutil/avstring.h"
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#include "libavutil/intreadwrite.h"
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#include "libavutil/mathematics.h"
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#include "libavutil/opt.h"
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#include "libavutil/dict.h"
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#include "avio_internal.h"
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#define INITIAL_BUFFER_SIZE 32768
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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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* 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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char url[MAX_URL_SIZE];
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char key[MAX_URL_SIZE];
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enum KeyType key_type;
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* Each variant has its own demuxer. If it currently is active,
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* it has an open AVIOContext too, and potentially an AVPacket
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* containing the next packet from this stream.
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char url[MAX_URL_SIZE];
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AVFormatContext *parent;
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struct segment **segments;
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int needed, cur_needed;
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int64_t last_load_time;
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char key_url[MAX_URL_SIZE];
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typedef struct AppleHTTPContext {
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struct variant **variants;
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int64_t first_timestamp;
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AVIOInterruptCB *interrupt_callback;
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static int read_chomp_line(AVIOContext *s, char *buf, int maxlen)
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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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static void free_segment_list(struct variant *var)
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for (i = 0; i < var->n_segments; i++)
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av_free(var->segments[i]);
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av_freep(&var->segments);
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static void free_variant_list(AppleHTTPContext *c)
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for (i = 0; i < c->n_variants; i++) {
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struct variant *var = c->variants[i];
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free_segment_list(var);
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av_free_packet(&var->pkt);
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av_free(var->pb.buffer);
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ffurl_close(var->input);
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avformat_close_input(&var->ctx);
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av_freep(&c->variants);
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* Used to reset a statically allocated AVPacket to a clean slate,
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* containing no data.
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static void reset_packet(AVPacket *pkt)
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static struct variant *new_variant(AppleHTTPContext *c, int bandwidth,
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const char *url, const char *base)
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struct variant *var = av_mallocz(sizeof(struct variant));
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reset_packet(&var->pkt);
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var->bandwidth = bandwidth;
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ff_make_absolute_url(var->url, sizeof(var->url), base, url);
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dynarray_add(&c->variants, &c->n_variants, var);
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struct variant_info {
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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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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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char uri[MAX_URL_SIZE];
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static void handle_key_args(struct key_info *info, const char *key,
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int key_len, char **dest, int *dest_len)
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if (!strncmp(key, "METHOD=", key_len)) {
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*dest = info->method;
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*dest_len = sizeof(info->method);
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} else if (!strncmp(key, "URI=", key_len)) {
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*dest_len = sizeof(info->uri);
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} else if (!strncmp(key, "IV=", key_len)) {
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*dest_len = sizeof(info->iv);
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static int parse_playlist(AppleHTTPContext *c, const char *url,
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struct variant *var, AVIOContext *in)
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int ret = 0, duration = 0, is_segment = 0, is_variant = 0, bandwidth = 0;
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enum KeyType key_type = KEY_NONE;
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char key[MAX_URL_SIZE] = "";
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if ((ret = avio_open2(&in, url, AVIO_FLAG_READ,
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c->interrupt_callback, NULL)) < 0)
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read_chomp_line(in, line, sizeof(line));
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if (strcmp(line, "#EXTM3U")) {
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ret = AVERROR_INVALIDDATA;
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free_segment_list(var);
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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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ff_parse_key_value(ptr, (ff_parse_key_val_cb) handle_variant_args,
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bandwidth = atoi(info.bandwidth);
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} else if (av_strstart(line, "#EXT-X-KEY:", &ptr)) {
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struct key_info info = {{0}};
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ff_parse_key_value(ptr, (ff_parse_key_val_cb) handle_key_args,
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if (!strcmp(info.method, "AES-128"))
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key_type = KEY_AES_128;
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if (!strncmp(info.iv, "0x", 2) || !strncmp(info.iv, "0X", 2)) {
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ff_hex_to_data(iv, info.iv + 2);
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av_strlcpy(key, info.uri, sizeof(key));
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} else if (av_strstart(line, "#EXT-X-TARGETDURATION:", &ptr)) {
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var = new_variant(c, 0, url, NULL);
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ret = AVERROR(ENOMEM);
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var->target_duration = atoi(ptr);
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} else if (av_strstart(line, "#EXT-X-MEDIA-SEQUENCE:", &ptr)) {
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var = new_variant(c, 0, url, NULL);
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ret = AVERROR(ENOMEM);
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var->start_seq_no = atoi(ptr);
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} else if (av_strstart(line, "#EXT-X-ENDLIST", &ptr)) {
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} else if (av_strstart(line, "#EXTINF:", &ptr)) {
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duration = atoi(ptr);
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} else if (av_strstart(line, "#", NULL)) {
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} else if (line[0]) {
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if (!new_variant(c, bandwidth, line, url)) {
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ret = AVERROR(ENOMEM);
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var = new_variant(c, 0, url, NULL);
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ret = AVERROR(ENOMEM);
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seg = av_malloc(sizeof(struct segment));
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ret = AVERROR(ENOMEM);
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seg->duration = duration;
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seg->key_type = key_type;
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memcpy(seg->iv, iv, sizeof(iv));
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int seq = var->start_seq_no + var->n_segments;
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memset(seg->iv, 0, sizeof(seg->iv));
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AV_WB32(seg->iv + 12, seq);
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ff_make_absolute_url(seg->key, sizeof(seg->key), url, key);
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ff_make_absolute_url(seg->url, sizeof(seg->url), url, line);
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dynarray_add(&var->segments, &var->n_segments, seg);
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var->last_load_time = av_gettime();
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static int open_input(struct variant *var)
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struct segment *seg = var->segments[var->cur_seq_no - var->start_seq_no];
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if (seg->key_type == KEY_NONE) {
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return ffurl_open(&var->input, seg->url, AVIO_FLAG_READ,
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&var->parent->interrupt_callback, NULL);
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} else if (seg->key_type == KEY_AES_128) {
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char iv[33], key[33], url[MAX_URL_SIZE];
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if (strcmp(seg->key, var->key_url)) {
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if (ffurl_open(&uc, seg->key, AVIO_FLAG_READ,
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&var->parent->interrupt_callback, NULL) == 0) {
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if (ffurl_read_complete(uc, var->key, sizeof(var->key))
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!= sizeof(var->key)) {
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av_log(NULL, AV_LOG_ERROR, "Unable to read key file %s\n",
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av_log(NULL, AV_LOG_ERROR, "Unable to open key file %s\n",
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av_strlcpy(var->key_url, seg->key, sizeof(var->key_url));
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ff_data_to_hex(iv, seg->iv, sizeof(seg->iv), 0);
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ff_data_to_hex(key, var->key, sizeof(var->key), 0);
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iv[32] = key[32] = '\0';
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if (strstr(seg->url, "://"))
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snprintf(url, sizeof(url), "crypto+%s", seg->url);
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snprintf(url, sizeof(url), "crypto:%s", seg->url);
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if ((ret = ffurl_alloc(&var->input, url, AVIO_FLAG_READ,
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&var->parent->interrupt_callback)) < 0)
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av_opt_set(var->input->priv_data, "key", key, 0);
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av_opt_set(var->input->priv_data, "iv", iv, 0);
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if ((ret = ffurl_connect(var->input, NULL)) < 0) {
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ffurl_close(var->input);
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return AVERROR(ENOSYS);
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static int read_data(void *opaque, uint8_t *buf, int buf_size)
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struct variant *v = opaque;
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AppleHTTPContext *c = v->parent->priv_data;
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/* If this is a live stream and the reload interval has elapsed since
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* the last playlist reload, reload the variant playlists now. */
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int64_t reload_interval = v->n_segments > 0 ?
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v->segments[v->n_segments - 1]->duration :
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reload_interval *= 1000000;
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av_gettime() - v->last_load_time >= reload_interval) {
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if ((ret = parse_playlist(c, v->url, v, NULL)) < 0)
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/* If we need to reload the playlist again below (if
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* there's still no more segments), switch to a reload
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* interval of half the target duration. */
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reload_interval = v->target_duration * 500000;
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if (v->cur_seq_no < v->start_seq_no) {
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av_log(NULL, AV_LOG_WARNING,
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"skipping %d segments ahead, expired from playlists\n",
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v->start_seq_no - v->cur_seq_no);
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v->cur_seq_no = v->start_seq_no;
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if (v->cur_seq_no >= v->start_seq_no + v->n_segments) {
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while (av_gettime() - v->last_load_time < reload_interval) {
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if (ff_check_interrupt(c->interrupt_callback))
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/* Enough time has elapsed since the last reload */
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ret = ffurl_read(v->input, buf, buf_size);
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if (ret < 0 && ret != AVERROR_EOF)
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ffurl_close(v->input);
427
c->end_of_segment = 1;
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c->cur_seq_no = v->cur_seq_no;
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if (v->ctx && v->ctx->nb_streams) {
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for (i = v->stream_offset; i < v->stream_offset + v->ctx->nb_streams;
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if (v->parent->streams[i]->discard < AVDISCARD_ALL)
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av_log(v->parent, AV_LOG_INFO, "No longer receiving variant %d\n",
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static int applehttp_read_header(AVFormatContext *s, AVFormatParameters *ap)
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AppleHTTPContext *c = s->priv_data;
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int ret = 0, i, j, stream_offset = 0;
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c->interrupt_callback = &s->interrupt_callback;
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if ((ret = parse_playlist(c, s->filename, NULL, s->pb)) < 0)
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if (c->n_variants == 0) {
457
av_log(NULL, AV_LOG_WARNING, "Empty playlist\n");
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/* If the playlist only contained variants, parse each individual
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* variant playlist. */
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if (c->n_variants > 1 || c->variants[0]->n_segments == 0) {
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for (i = 0; i < c->n_variants; i++) {
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struct variant *v = c->variants[i];
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if ((ret = parse_playlist(c, v->url, v, NULL)) < 0)
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if (c->variants[0]->n_segments == 0) {
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av_log(NULL, AV_LOG_WARNING, "Empty playlist\n");
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/* If this isn't a live stream, calculate the total duration of the
479
if (c->variants[0]->finished) {
480
int64_t duration = 0;
481
for (i = 0; i < c->variants[0]->n_segments; i++)
482
duration += c->variants[0]->segments[i]->duration;
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s->duration = duration * AV_TIME_BASE;
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/* Open the demuxer for each variant */
487
for (i = 0; i < c->n_variants; i++) {
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struct variant *v = c->variants[i];
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AVInputFormat *in_fmt = NULL;
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char bitrate_str[20];
491
if (v->n_segments == 0)
494
if (!(v->ctx = avformat_alloc_context())) {
495
ret = AVERROR(ENOMEM);
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/* If this is a live stream with more than 3 segments, start at the
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* third last segment. */
505
v->cur_seq_no = v->start_seq_no;
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if (!v->finished && v->n_segments > 3)
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v->cur_seq_no = v->start_seq_no + v->n_segments - 3;
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v->read_buffer = av_malloc(INITIAL_BUFFER_SIZE);
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ffio_init_context(&v->pb, v->read_buffer, INITIAL_BUFFER_SIZE, 0, v,
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read_data, NULL, NULL);
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ret = av_probe_input_buffer(&v->pb, &in_fmt, v->segments[0]->url,
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/* Free the ctx - it isn't initialized properly at this point,
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* so avformat_close_input shouldn't be called. If
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* avformat_open_input fails below, it frees and zeros the
519
* context, so it doesn't need any special treatment like this. */
520
avformat_free_context(v->ctx);
525
ret = avformat_open_input(&v->ctx, v->segments[0]->url, in_fmt, NULL);
528
v->stream_offset = stream_offset;
529
snprintf(bitrate_str, sizeof(bitrate_str), "%d", v->bandwidth);
530
/* Create new AVStreams for each stream in this variant */
531
for (j = 0; j < v->ctx->nb_streams; j++) {
532
AVStream *st = avformat_new_stream(s, NULL);
534
ret = AVERROR(ENOMEM);
538
avcodec_copy_context(st->codec, v->ctx->streams[j]->codec);
540
av_dict_set(&st->metadata, "variant_bitrate", bitrate_str,
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stream_offset += v->ctx->nb_streams;
547
c->first_timestamp = AV_NOPTS_VALUE;
551
free_variant_list(c);
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static int recheck_discard_flags(AVFormatContext *s, int first)
557
AppleHTTPContext *c = s->priv_data;
560
/* Check if any new streams are needed */
561
for (i = 0; i < c->n_variants; i++)
562
c->variants[i]->cur_needed = 0;;
564
for (i = 0; i < s->nb_streams; i++) {
565
AVStream *st = s->streams[i];
566
struct variant *var = c->variants[s->streams[i]->id];
567
if (st->discard < AVDISCARD_ALL)
570
for (i = 0; i < c->n_variants; i++) {
571
struct variant *v = c->variants[i];
572
if (v->cur_needed && !v->needed) {
575
v->cur_seq_no = c->cur_seq_no;
576
v->pb.eof_reached = 0;
577
av_log(s, AV_LOG_INFO, "Now receiving variant %d\n", i);
578
} else if (first && !v->cur_needed && v->needed) {
580
ffurl_close(v->input);
584
av_log(s, AV_LOG_INFO, "No longer receiving variant %d\n", i);
590
static int applehttp_read_packet(AVFormatContext *s, AVPacket *pkt)
592
AppleHTTPContext *c = s->priv_data;
593
int ret, i, minvariant = -1;
595
if (c->first_packet) {
596
recheck_discard_flags(s, 1);
601
c->end_of_segment = 0;
602
for (i = 0; i < c->n_variants; i++) {
603
struct variant *var = c->variants[i];
604
/* Make sure we've got one buffered packet from each open variant
606
if (var->needed && !var->pkt.data) {
607
ret = av_read_frame(var->ctx, &var->pkt);
609
if (!var->pb.eof_reached)
611
reset_packet(&var->pkt);
613
if (c->first_timestamp == AV_NOPTS_VALUE)
614
c->first_timestamp = var->pkt.dts;
617
/* Check if this stream has the packet with the lowest dts */
619
if (minvariant < 0 ||
620
var->pkt.dts < c->variants[minvariant]->pkt.dts)
624
if (c->end_of_segment) {
625
if (recheck_discard_flags(s, 0))
628
/* If we got a packet, return it */
629
if (minvariant >= 0) {
630
*pkt = c->variants[minvariant]->pkt;
631
pkt->stream_index += c->variants[minvariant]->stream_offset;
632
reset_packet(&c->variants[minvariant]->pkt);
638
static int applehttp_close(AVFormatContext *s)
640
AppleHTTPContext *c = s->priv_data;
642
free_variant_list(c);
646
static int applehttp_read_seek(AVFormatContext *s, int stream_index,
647
int64_t timestamp, int flags)
649
AppleHTTPContext *c = s->priv_data;
652
if ((flags & AVSEEK_FLAG_BYTE) || !c->variants[0]->finished)
653
return AVERROR(ENOSYS);
655
timestamp = av_rescale_rnd(timestamp, 1, stream_index >= 0 ?
656
s->streams[stream_index]->time_base.den :
657
AV_TIME_BASE, flags & AVSEEK_FLAG_BACKWARD ?
658
AV_ROUND_DOWN : AV_ROUND_UP);
660
for (i = 0; i < c->n_variants; i++) {
662
struct variant *var = c->variants[i];
663
int64_t pos = c->first_timestamp == AV_NOPTS_VALUE ? 0 :
664
av_rescale_rnd(c->first_timestamp, 1,
665
stream_index >= 0 ? s->streams[stream_index]->time_base.den : AV_TIME_BASE,
666
flags & AVSEEK_FLAG_BACKWARD ? AV_ROUND_DOWN : AV_ROUND_UP);
668
ffurl_close(var->input);
671
av_free_packet(&var->pkt);
672
reset_packet(&var->pkt);
673
var->pb.eof_reached = 0;
675
/* Locate the segment that contains the target timestamp */
676
for (j = 0; j < var->n_segments; j++) {
677
if (timestamp >= pos &&
678
timestamp < pos + var->segments[j]->duration) {
679
var->cur_seq_no = var->start_seq_no + j;
683
pos += var->segments[j]->duration;
689
static int applehttp_probe(AVProbeData *p)
691
/* Require #EXTM3U at the start, and either one of the ones below
692
* somewhere for a proper match. */
693
if (strncmp(p->buf, "#EXTM3U", 7))
695
if (strstr(p->buf, "#EXT-X-STREAM-INF:") ||
696
strstr(p->buf, "#EXT-X-TARGETDURATION:") ||
697
strstr(p->buf, "#EXT-X-MEDIA-SEQUENCE:"))
698
return AVPROBE_SCORE_MAX;
702
AVInputFormat ff_applehttp_demuxer = {
704
.long_name = NULL_IF_CONFIG_SMALL("Apple HTTP Live Streaming format"),
705
.priv_data_size = sizeof(AppleHTTPContext),
706
.read_probe = applehttp_probe,
707
.read_header = applehttp_read_header,
708
.read_packet = applehttp_read_packet,
709
.read_close = applehttp_close,
710
.read_seek = applehttp_read_seek,
added
removed
libavformat/applehttp.c
