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ffmpeg/libavformat/hls.c

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/*
* Apple HTTP Live Streaming demuxer
* Copyright (c) 2010 Martin Storsjo
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
* Apple HTTP Live Streaming demuxer
* http://tools.ietf.org/html/draft-pantos-http-live-streaming
*/
#include "libavutil/avstring.h"
#include "libavutil/intreadwrite.h"
#include "libavutil/mathematics.h"
#include "libavutil/opt.h"
#include "libavutil/dict.h"
#include "libavutil/time.h"
#include "avformat.h"
#include "internal.h"
#include "avio_internal.h"
#include "url.h"
#define INITIAL_BUFFER_SIZE 32768
/*
* An apple http stream consists of a playlist with media segment files,
* played sequentially. There may be several playlists with the same
* video content, in different bandwidth variants, that are played in
* parallel (preferably only one bandwidth variant at a time). In this case,
* the user supplied the url to a main playlist that only lists the variant
* playlists.
*
* If the main playlist doesn't point at any variants, we still create
* one anonymous toplevel variant for this, to maintain the structure.
*/
enum KeyType {
KEY_NONE,
KEY_AES_128,
};
struct segment {
int duration;
char url[MAX_URL_SIZE];
char key[MAX_URL_SIZE];
enum KeyType key_type;
uint8_t iv[16];
};
/*
* Each variant has its own demuxer. If it currently is active,
* it has an open AVIOContext too, and potentially an AVPacket
* containing the next packet from this stream.
*/
struct variant {
int bandwidth;
char url[MAX_URL_SIZE];
AVIOContext pb;
uint8_t* read_buffer;
URLContext *input;
AVFormatContext *parent;
int index;
AVFormatContext *ctx;
AVPacket pkt;
int stream_offset;
int finished;
int target_duration;
int start_seq_no;
int n_segments;
struct segment **segments;
int needed, cur_needed;
int cur_seq_no;
int64_t last_load_time;
char key_url[MAX_URL_SIZE];
uint8_t key[16];
};
typedef struct HLSContext {
int n_variants;
struct variant **variants;
int cur_seq_no;
int end_of_segment;
int first_packet;
int64_t first_timestamp;
int64_t seek_timestamp;
int seek_flags;
AVIOInterruptCB *interrupt_callback;
} HLSContext;
static int read_chomp_line(AVIOContext *s, char *buf, int maxlen)
{
int len = ff_get_line(s, buf, maxlen);
while (len > 0 && isspace(buf[len - 1]))
buf[--len] = '\0';
return len;
}
static void free_segment_list(struct variant *var)
{
int i;
for (i = 0; i < var->n_segments; i++)
av_free(var->segments[i]);
av_freep(&var->segments);
var->n_segments = 0;
}
static void free_variant_list(HLSContext *c)
{
int i;
for (i = 0; i < c->n_variants; i++) {
struct variant *var = c->variants[i];
free_segment_list(var);
av_free_packet(&var->pkt);
av_free(var->pb.buffer);
if (var->input)
ffurl_close(var->input);
if (var->ctx) {
var->ctx->pb = NULL;
avformat_close_input(&var->ctx);
}
av_free(var);
}
av_freep(&c->variants);
c->n_variants = 0;
}
/*
* Used to reset a statically allocated AVPacket to a clean slate,
* containing no data.
*/
static void reset_packet(AVPacket *pkt)
{
av_init_packet(pkt);
pkt->data = NULL;
}
static struct variant *new_variant(HLSContext *c, int bandwidth,
const char *url, const char *base)
{
struct variant *var = av_mallocz(sizeof(struct variant));
if (!var)
return NULL;
reset_packet(&var->pkt);
var->bandwidth = bandwidth;
ff_make_absolute_url(var->url, sizeof(var->url), base, url);
dynarray_add(&c->variants, &c->n_variants, var);
return var;
}
struct variant_info {
char bandwidth[20];
};
static void handle_variant_args(struct variant_info *info, const char *key,
int key_len, char **dest, int *dest_len)
{
if (!strncmp(key, "BANDWIDTH=", key_len)) {
*dest = info->bandwidth;
*dest_len = sizeof(info->bandwidth);
}
}
struct key_info {
char uri[MAX_URL_SIZE];
char method[10];
char iv[35];
};
static void handle_key_args(struct key_info *info, const char *key,
int key_len, char **dest, int *dest_len)
{
if (!strncmp(key, "METHOD=", key_len)) {
*dest = info->method;
*dest_len = sizeof(info->method);
} else if (!strncmp(key, "URI=", key_len)) {
*dest = info->uri;
*dest_len = sizeof(info->uri);
} else if (!strncmp(key, "IV=", key_len)) {
*dest = info->iv;
*dest_len = sizeof(info->iv);
}
}
static int parse_playlist(HLSContext *c, const char *url,
struct variant *var, AVIOContext *in)
{
int ret = 0, duration = 0, is_segment = 0, is_variant = 0, bandwidth = 0;
enum KeyType key_type = KEY_NONE;
uint8_t iv[16] = "";
int has_iv = 0;
char key[MAX_URL_SIZE] = "";
char line[1024];
const char *ptr;
int close_in = 0;
if (!in) {
close_in = 1;
if ((ret = avio_open2(&in, url, AVIO_FLAG_READ,
c->interrupt_callback, NULL)) < 0)
return ret;
}
read_chomp_line(in, line, sizeof(line));
if (strcmp(line, "#EXTM3U")) {
ret = AVERROR_INVALIDDATA;
goto fail;
}
if (var) {
free_segment_list(var);
var->finished = 0;
}
while (!url_feof(in)) {
read_chomp_line(in, line, sizeof(line));
if (av_strstart(line, "#EXT-X-STREAM-INF:", &ptr)) {
struct variant_info info = {{0}};
is_variant = 1;
ff_parse_key_value(ptr, (ff_parse_key_val_cb) handle_variant_args,
&info);
bandwidth = atoi(info.bandwidth);
} else if (av_strstart(line, "#EXT-X-KEY:", &ptr)) {
struct key_info info = {{0}};
ff_parse_key_value(ptr, (ff_parse_key_val_cb) handle_key_args,
&info);
key_type = KEY_NONE;
has_iv = 0;
if (!strcmp(info.method, "AES-128"))
key_type = KEY_AES_128;
if (!strncmp(info.iv, "0x", 2) || !strncmp(info.iv, "0X", 2)) {
ff_hex_to_data(iv, info.iv + 2);
has_iv = 1;
}
av_strlcpy(key, info.uri, sizeof(key));
} else if (av_strstart(line, "#EXT-X-TARGETDURATION:", &ptr)) {
if (!var) {
var = new_variant(c, 0, url, NULL);
if (!var) {
ret = AVERROR(ENOMEM);
goto fail;
}
}
var->target_duration = atoi(ptr);
} else if (av_strstart(line, "#EXT-X-MEDIA-SEQUENCE:", &ptr)) {
if (!var) {
var = new_variant(c, 0, url, NULL);
if (!var) {
ret = AVERROR(ENOMEM);
goto fail;
}
}
var->start_seq_no = atoi(ptr);
} else if (av_strstart(line, "#EXT-X-ENDLIST", &ptr)) {
if (var)
var->finished = 1;
} else if (av_strstart(line, "#EXTINF:", &ptr)) {
is_segment = 1;
duration = atoi(ptr);
} else if (av_strstart(line, "#", NULL)) {
continue;
} else if (line[0]) {
if (is_variant) {
if (!new_variant(c, bandwidth, line, url)) {
ret = AVERROR(ENOMEM);
goto fail;
}
is_variant = 0;
bandwidth = 0;
}
if (is_segment) {
struct segment *seg;
if (!var) {
var = new_variant(c, 0, url, NULL);
if (!var) {
ret = AVERROR(ENOMEM);
goto fail;
}
}
seg = av_malloc(sizeof(struct segment));
if (!seg) {
ret = AVERROR(ENOMEM);
goto fail;
}
seg->duration = duration;
seg->key_type = key_type;
if (has_iv) {
memcpy(seg->iv, iv, sizeof(iv));
} else {
int seq = var->start_seq_no + var->n_segments;
memset(seg->iv, 0, sizeof(seg->iv));
AV_WB32(seg->iv + 12, seq);
}
ff_make_absolute_url(seg->key, sizeof(seg->key), url, key);
ff_make_absolute_url(seg->url, sizeof(seg->url), url, line);
dynarray_add(&var->segments, &var->n_segments, seg);
is_segment = 0;
}
}
}
if (var)
var->last_load_time = av_gettime();
fail:
if (close_in)
avio_close(in);
return ret;
}
static int open_input(struct variant *var)
{
struct segment *seg = var->segments[var->cur_seq_no - var->start_seq_no];
if (seg->key_type == KEY_NONE) {
return ffurl_open(&var->input, seg->url, AVIO_FLAG_READ,
&var->parent->interrupt_callback, NULL);
} else if (seg->key_type == KEY_AES_128) {
char iv[33], key[33], url[MAX_URL_SIZE];
int ret;
if (strcmp(seg->key, var->key_url)) {
URLContext *uc;
if (ffurl_open(&uc, seg->key, AVIO_FLAG_READ,
&var->parent->interrupt_callback, NULL) == 0) {
if (ffurl_read_complete(uc, var->key, sizeof(var->key))
!= sizeof(var->key)) {
av_log(NULL, AV_LOG_ERROR, "Unable to read key file %s\n",
seg->key);
}
ffurl_close(uc);
} else {
av_log(NULL, AV_LOG_ERROR, "Unable to open key file %s\n",
seg->key);
}
av_strlcpy(var->key_url, seg->key, sizeof(var->key_url));
}
ff_data_to_hex(iv, seg->iv, sizeof(seg->iv), 0);
ff_data_to_hex(key, var->key, sizeof(var->key), 0);
iv[32] = key[32] = '\0';
if (strstr(seg->url, "://"))
snprintf(url, sizeof(url), "crypto+%s", seg->url);
else
snprintf(url, sizeof(url), "crypto:%s", seg->url);
if ((ret = ffurl_alloc(&var->input, url, AVIO_FLAG_READ,
&var->parent->interrupt_callback)) < 0)
return ret;
av_opt_set(var->input->priv_data, "key", key, 0);
av_opt_set(var->input->priv_data, "iv", iv, 0);
if ((ret = ffurl_connect(var->input, NULL)) < 0) {
ffurl_close(var->input);
var->input = NULL;
return ret;
}
return 0;
}
return AVERROR(ENOSYS);
}
static int read_data(void *opaque, uint8_t *buf, int buf_size)
{
struct variant *v = opaque;
HLSContext *c = v->parent->priv_data;
int ret, i;
restart:
if (!v->input) {
/* If this is a live stream and the reload interval has elapsed since
* the last playlist reload, reload the variant playlists now. */
int64_t reload_interval = v->n_segments > 0 ?
v->segments[v->n_segments - 1]->duration :
v->target_duration;
reload_interval *= 1000000;
reload:
if (!v->finished &&
av_gettime() - v->last_load_time >= reload_interval) {
if ((ret = parse_playlist(c, v->url, v, NULL)) < 0)
return ret;
/* If we need to reload the playlist again below (if
* there's still no more segments), switch to a reload
* interval of half the target duration. */
reload_interval = v->target_duration * 500000;
}
if (v->cur_seq_no < v->start_seq_no) {
av_log(NULL, AV_LOG_WARNING,
"skipping %d segments ahead, expired from playlists\n",
v->start_seq_no - v->cur_seq_no);
v->cur_seq_no = v->start_seq_no;
}
if (v->cur_seq_no >= v->start_seq_no + v->n_segments) {
if (v->finished)
return AVERROR_EOF;
while (av_gettime() - v->last_load_time < reload_interval) {
if (ff_check_interrupt(c->interrupt_callback))
return AVERROR_EXIT;
av_usleep(100*1000);
}
/* Enough time has elapsed since the last reload */
goto reload;
}
ret = open_input(v);
if (ret < 0)
return ret;
}
ret = ffurl_read(v->input, buf, buf_size);
if (ret > 0)
return ret;
if (ret < 0 && ret != AVERROR_EOF)
return ret;
ffurl_close(v->input);
v->input = NULL;
v->cur_seq_no++;
c->end_of_segment = 1;
c->cur_seq_no = v->cur_seq_no;
if (v->ctx && v->ctx->nb_streams) {
v->needed = 0;
for (i = v->stream_offset; i < v->stream_offset + v->ctx->nb_streams;
i++) {
if (v->parent->streams[i]->discard < AVDISCARD_ALL)
v->needed = 1;
}
}
if (!v->needed) {
av_log(v->parent, AV_LOG_INFO, "No longer receiving variant %d\n",
v->index);
return AVERROR_EOF;
}
goto restart;
}
static int hls_read_header(AVFormatContext *s)
{
HLSContext *c = s->priv_data;
int ret = 0, i, j, stream_offset = 0;
c->interrupt_callback = &s->interrupt_callback;
if ((ret = parse_playlist(c, s->filename, NULL, s->pb)) < 0)
goto fail;
if (c->n_variants == 0) {
av_log(NULL, AV_LOG_WARNING, "Empty playlist\n");
ret = AVERROR_EOF;
goto fail;
}
/* If the playlist only contained variants, parse each individual
* variant playlist. */
if (c->n_variants > 1 || c->variants[0]->n_segments == 0) {
for (i = 0; i < c->n_variants; i++) {
struct variant *v = c->variants[i];
if ((ret = parse_playlist(c, v->url, v, NULL)) < 0)
goto fail;
}
}
if (c->variants[0]->n_segments == 0) {
av_log(NULL, AV_LOG_WARNING, "Empty playlist\n");
ret = AVERROR_EOF;
goto fail;
}
/* If this isn't a live stream, calculate the total duration of the
* stream. */
if (c->variants[0]->finished) {
int64_t duration = 0;
for (i = 0; i < c->variants[0]->n_segments; i++)
duration += c->variants[0]->segments[i]->duration;
s->duration = duration * AV_TIME_BASE;
}
/* Open the demuxer for each variant */
for (i = 0; i < c->n_variants; i++) {
struct variant *v = c->variants[i];
AVInputFormat *in_fmt = NULL;
char bitrate_str[20];
if (v->n_segments == 0)
continue;
if (!(v->ctx = avformat_alloc_context())) {
ret = AVERROR(ENOMEM);
goto fail;
}
v->index = i;
v->needed = 1;
v->parent = s;
/* If this is a live stream with more than 3 segments, start at the
* third last segment. */
v->cur_seq_no = v->start_seq_no;
if (!v->finished && v->n_segments > 3)
v->cur_seq_no = v->start_seq_no + v->n_segments - 3;
v->read_buffer = av_malloc(INITIAL_BUFFER_SIZE);
ffio_init_context(&v->pb, v->read_buffer, INITIAL_BUFFER_SIZE, 0, v,
read_data, NULL, NULL);
v->pb.seekable = 0;
ret = av_probe_input_buffer(&v->pb, &in_fmt, v->segments[0]->url,
NULL, 0, 0);
if (ret < 0) {
/* Free the ctx - it isn't initialized properly at this point,
* so avformat_close_input shouldn't be called. If
* avformat_open_input fails below, it frees and zeros the
* context, so it doesn't need any special treatment like this. */
av_log(s, AV_LOG_ERROR, "Error when loading first segment '%s'\n", v->segments[0]->url);
avformat_free_context(v->ctx);
v->ctx = NULL;
goto fail;
}
v->ctx->pb = &v->pb;
ret = avformat_open_input(&v->ctx, v->segments[0]->url, in_fmt, NULL);
if (ret < 0)
goto fail;
v->stream_offset = stream_offset;
snprintf(bitrate_str, sizeof(bitrate_str), "%d", v->bandwidth);
/* Create new AVStreams for each stream in this variant */
for (j = 0; j < v->ctx->nb_streams; j++) {
AVStream *st = avformat_new_stream(s, NULL);
if (!st) {
ret = AVERROR(ENOMEM);
goto fail;
}
st->id = i;
avcodec_copy_context(st->codec, v->ctx->streams[j]->codec);
if (v->bandwidth)
av_dict_set(&st->metadata, "variant_bitrate", bitrate_str,
0);
}
stream_offset += v->ctx->nb_streams;
}
c->first_packet = 1;
c->first_timestamp = AV_NOPTS_VALUE;
c->seek_timestamp = AV_NOPTS_VALUE;
return 0;
fail:
free_variant_list(c);
return ret;
}
static int recheck_discard_flags(AVFormatContext *s, int first)
{
HLSContext *c = s->priv_data;
int i, changed = 0;
/* Check if any new streams are needed */
for (i = 0; i < c->n_variants; i++)
c->variants[i]->cur_needed = 0;
for (i = 0; i < s->nb_streams; i++) {
AVStream *st = s->streams[i];
struct variant *var = c->variants[s->streams[i]->id];
if (st->discard < AVDISCARD_ALL)
var->cur_needed = 1;
}
for (i = 0; i < c->n_variants; i++) {
struct variant *v = c->variants[i];
if (v->cur_needed && !v->needed) {
v->needed = 1;
changed = 1;
v->cur_seq_no = c->cur_seq_no;
v->pb.eof_reached = 0;
av_log(s, AV_LOG_INFO, "Now receiving variant %d\n", i);
} else if (first && !v->cur_needed && v->needed) {
if (v->input)
ffurl_close(v->input);
v->input = NULL;
v->needed = 0;
changed = 1;
av_log(s, AV_LOG_INFO, "No longer receiving variant %d\n", i);
}
}
return changed;
}
static int hls_read_packet(AVFormatContext *s, AVPacket *pkt)
{
HLSContext *c = s->priv_data;
int ret, i, minvariant = -1;
if (c->first_packet) {
recheck_discard_flags(s, 1);
c->first_packet = 0;
}
start:
c->end_of_segment = 0;
for (i = 0; i < c->n_variants; i++) {
struct variant *var = c->variants[i];
/* Make sure we've got one buffered packet from each open variant
* stream */
if (var->needed && !var->pkt.data) {
while (1) {
int64_t ts_diff;
AVStream *st;
ret = av_read_frame(var->ctx, &var->pkt);
if (ret < 0) {
if (!url_feof(&var->pb))
return ret;
reset_packet(&var->pkt);
break;
} else {
if (c->first_timestamp == AV_NOPTS_VALUE)
c->first_timestamp = var->pkt.dts;
}
if (c->seek_timestamp == AV_NOPTS_VALUE)
break;
if (var->pkt.dts == AV_NOPTS_VALUE) {
c->seek_timestamp = AV_NOPTS_VALUE;
break;
}
st = var->ctx->streams[var->pkt.stream_index];
ts_diff = av_rescale_rnd(var->pkt.dts, AV_TIME_BASE,
st->time_base.den, AV_ROUND_DOWN) -
c->seek_timestamp;
if (ts_diff >= 0 && (c->seek_flags & AVSEEK_FLAG_ANY ||
var->pkt.flags & AV_PKT_FLAG_KEY)) {
c->seek_timestamp = AV_NOPTS_VALUE;
break;
}
}
}
/* Check if this stream has the packet with the lowest dts */
if (var->pkt.data) {
if (minvariant < 0 ||
var->pkt.dts < c->variants[minvariant]->pkt.dts)
minvariant = i;
}
}
if (c->end_of_segment) {
if (recheck_discard_flags(s, 0))
goto start;
}
/* If we got a packet, return it */
if (minvariant >= 0) {
*pkt = c->variants[minvariant]->pkt;
pkt->stream_index += c->variants[minvariant]->stream_offset;
reset_packet(&c->variants[minvariant]->pkt);
return 0;
}
return AVERROR_EOF;
}
static int hls_close(AVFormatContext *s)
{
HLSContext *c = s->priv_data;
free_variant_list(c);
return 0;
}
static int hls_read_seek(AVFormatContext *s, int stream_index,
int64_t timestamp, int flags)
{
HLSContext *c = s->priv_data;
int i, j, ret;
if ((flags & AVSEEK_FLAG_BYTE) || !c->variants[0]->finished)
return AVERROR(ENOSYS);
c->seek_flags = flags;
c->seek_timestamp = stream_index < 0 ? timestamp :
av_rescale_rnd(timestamp, AV_TIME_BASE,
s->streams[stream_index]->time_base.den,
flags & AVSEEK_FLAG_BACKWARD ?
AV_ROUND_DOWN : AV_ROUND_UP);
timestamp = av_rescale_rnd(timestamp, 1, stream_index >= 0 ?
s->streams[stream_index]->time_base.den :
AV_TIME_BASE, flags & AVSEEK_FLAG_BACKWARD ?
AV_ROUND_DOWN : AV_ROUND_UP);
if (s->duration < c->seek_timestamp) {
c->seek_timestamp = AV_NOPTS_VALUE;
return AVERROR(EIO);
}
ret = AVERROR(EIO);
for (i = 0; i < c->n_variants; i++) {
/* Reset reading */
struct variant *var = c->variants[i];
int64_t pos = c->first_timestamp == AV_NOPTS_VALUE ? 0 :
av_rescale_rnd(c->first_timestamp, 1, stream_index >= 0 ?
s->streams[stream_index]->time_base.den :
AV_TIME_BASE, flags & AVSEEK_FLAG_BACKWARD ?
AV_ROUND_DOWN : AV_ROUND_UP);
if (var->input) {
ffurl_close(var->input);
var->input = NULL;
}
av_free_packet(&var->pkt);
reset_packet(&var->pkt);
var->pb.eof_reached = 0;
/* Clear any buffered data */
var->pb.buf_end = var->pb.buf_ptr = var->pb.buffer;
/* Reset the pos, to let the mpegts demuxer know we've seeked. */
var->pb.pos = 0;
/* Locate the segment that contains the target timestamp */
for (j = 0; j < var->n_segments; j++) {
if (timestamp >= pos &&
timestamp < pos + var->segments[j]->duration) {
var->cur_seq_no = var->start_seq_no + j;
ret = 0;
break;
}
pos += var->segments[j]->duration;
}
if (ret)
c->seek_timestamp = AV_NOPTS_VALUE;
}
return ret;
}
static int hls_probe(AVProbeData *p)
{
/* Require #EXTM3U at the start, and either one of the ones below
* somewhere for a proper match. */
if (strncmp(p->buf, "#EXTM3U", 7))
return 0;
if (strstr(p->buf, "#EXT-X-STREAM-INF:") ||
strstr(p->buf, "#EXT-X-TARGETDURATION:") ||
strstr(p->buf, "#EXT-X-MEDIA-SEQUENCE:"))
return AVPROBE_SCORE_MAX;
return 0;
}
AVInputFormat ff_hls_demuxer = {
.name = "hls,applehttp",
.long_name = NULL_IF_CONFIG_SMALL("Apple HTTP Live Streaming format"),
.priv_data_size = sizeof(HLSContext),
.read_probe = hls_probe,
.read_header = hls_read_header,
.read_packet = hls_read_packet,
.read_close = hls_close,
.read_seek = hls_read_seek,
};
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