ffmpeg/libavformat/applehttp.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
*/
#define _XOPEN_SOURCE 600
#include "libavutil/avstring.h"
#include "avformat.h"
#include "internal.h"
#include <unistd.h>
/*
* 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 (preferrably 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.
*/
struct segment {
int duration;
char url[MAX_URL_SIZE];
};
/*
* Each variant has its own demuxer. If it currently is active,
* it has an open ByteIOContext too, and potentially an AVPacket
* containing the next packet from this stream.
*/
struct variant {
int bandwidth;
char url[MAX_URL_SIZE];
ByteIOContext *pb;
AVFormatContext *ctx;
AVPacket pkt;
int stream_offset;
int start_seq_no;
int n_segments;
struct segment **segments;
int needed;
};
typedef struct AppleHTTPContext {
int target_duration;
int finished;
int n_variants;
struct variant **variants;
int cur_seq_no;
int64_t last_load_time;
int64_t last_packet_dts;
int max_start_seq, min_end_seq;
} AppleHTTPContext;
static int read_chomp_line(ByteIOContext *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 make_absolute_url(char *buf, int size, const char *base,
const char *rel)
{
char *sep;
/* If rel actually is an absolute url, just copy it */
if (!base || strstr(rel, "://") || rel[0] == '/') {
av_strlcpy(buf, rel, size);
return;
}
if (base != buf)
av_strlcpy(buf, base, size);
/* Remove the file name from the base url */
sep = strrchr(buf, '/');
if (sep)
sep[1] = '\0';
else
buf[0] = '\0';
while (av_strstart(rel, "../", NULL) && sep) {
/* Remove the path delimiter at the end */
sep[0] = '\0';
sep = strrchr(buf, '/');
/* If the next directory name to pop off is "..", break here */
if (!strcmp(sep ? &sep[1] : buf, "..")) {
/* Readd the slash we just removed */
av_strlcat(buf, "/", size);
break;
}
/* Cut off the directory name */
if (sep)
sep[1] = '\0';
else
buf[0] = '\0';
rel += 3;
}
av_strlcat(buf, rel, size);
}
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(AppleHTTPContext *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);
if (var->pb)
url_fclose(var->pb);
if (var->ctx) {
var->ctx->pb = NULL;
av_close_input_file(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(AppleHTTPContext *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;
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);
}
}
static int parse_playlist(AppleHTTPContext *c, const char *url,
struct variant *var, ByteIOContext *in)
{
int ret = 0, duration = 0, is_segment = 0, is_variant = 0, bandwidth = 0;
char line[1024];
const char *ptr;
int close_in = 0;
if (!in) {
close_in = 1;
if ((ret = url_fopen(&in, url, URL_RDONLY)) < 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);
c->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-TARGETDURATION:", &ptr)) {
c->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)) {
c->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;
make_absolute_url(seg->url, sizeof(seg->url), url, line);
dynarray_add(&var->segments, &var->n_segments, seg);
is_segment = 0;
}
}
}
c->last_load_time = av_gettime();
fail:
if (close_in)
url_fclose(in);
return ret;
}
static int applehttp_read_header(AVFormatContext *s, AVFormatParameters *ap)
{
AppleHTTPContext *c = s->priv_data;
int ret = 0, i, j, stream_offset = 0;
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->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;
}
c->min_end_seq = INT_MAX;
/* Open the demuxer for each variant */
for (i = 0; i < c->n_variants; i++) {
struct variant *v = c->variants[i];
if (v->n_segments == 0)
continue;
c->max_start_seq = FFMAX(c->max_start_seq, v->start_seq_no);
c->min_end_seq = FFMIN(c->min_end_seq, v->start_seq_no +
v->n_segments);
ret = av_open_input_file(&v->ctx, v->segments[0]->url, NULL, 0, NULL);
if (ret < 0)
goto fail;
url_fclose(v->ctx->pb);
v->ctx->pb = NULL;
v->stream_offset = stream_offset;
/* Create new AVStreams for each stream in this variant */
for (j = 0; j < v->ctx->nb_streams; j++) {
AVStream *st = av_new_stream(s, i);
if (!st) {
ret = AVERROR(ENOMEM);
goto fail;
}
avcodec_copy_context(st->codec, v->ctx->streams[j]->codec);
}
stream_offset += v->ctx->nb_streams;
}
c->last_packet_dts = AV_NOPTS_VALUE;
c->cur_seq_no = c->max_start_seq;
/* If this is a live stream with more than 3 segments, start at the
* third last segment. */
if (!c->finished && c->min_end_seq - c->max_start_seq > 3)
c->cur_seq_no = c->min_end_seq - 2;
return 0;
fail:
free_variant_list(c);
return ret;
}
static int open_variant(AppleHTTPContext *c, struct variant *var, int skip)
{
int ret;
if (c->cur_seq_no < var->start_seq_no) {
av_log(NULL, AV_LOG_WARNING,
"seq %d not available in variant %s, skipping\n",
var->start_seq_no, var->url);
return 0;
}
if (c->cur_seq_no - var->start_seq_no >= var->n_segments)
return c->finished ? AVERROR_EOF : 0;
ret = url_fopen(&var->pb,
var->segments[c->cur_seq_no - var->start_seq_no]->url,
URL_RDONLY);
if (ret < 0)
return ret;
var->ctx->pb = var->pb;
/* If this is a new segment in parallel with another one already opened,
* skip ahead so they're all at the same dts. */
if (skip && c->last_packet_dts != AV_NOPTS_VALUE) {
while (1) {
ret = av_read_frame(var->ctx, &var->pkt);
if (ret < 0) {
if (ret == AVERROR_EOF) {
reset_packet(&var->pkt);
return 0;
}
return ret;
}
if (var->pkt.dts >= c->last_packet_dts)
break;
av_free_packet(&var->pkt);
}
}
return 0;
}
static int applehttp_read_packet(AVFormatContext *s, AVPacket *pkt)
{
AppleHTTPContext *c = s->priv_data;
int ret, i, minvariant = -1, first = 1, needed = 0, changed = 0,
variants = 0;
/* Recheck the discard flags - which streams are desired at the moment */
for (i = 0; i < c->n_variants; i++)
c->variants[i]->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->needed = 1;
needed++;
}
/* Copy the discard flag to the chained demuxer, to indicate which
* streams are desired. */
var->ctx->streams[i - var->stream_offset]->discard = st->discard;
}
if (!needed)
return AVERROR_EOF;
start:
for (i = 0; i < c->n_variants; i++) {
struct variant *var = c->variants[i];
/* Close unneeded streams, open newly requested streams */
if (var->pb && !var->needed) {
av_log(s, AV_LOG_DEBUG,
"Closing variant stream %d, no longer needed\n", i);
av_free_packet(&var->pkt);
reset_packet(&var->pkt);
url_fclose(var->pb);
var->pb = NULL;
changed = 1;
} else if (!var->pb && var->needed) {
if (first)
av_log(s, AV_LOG_DEBUG, "Opening variant stream %d\n", i);
if (first && !c->finished)
if ((ret = parse_playlist(c, var->url, var, NULL)) < 0)
return ret;
ret = open_variant(c, var, first);
if (ret < 0)
return ret;
changed = 1;
}
/* Count the number of open variants */
if (var->pb)
variants++;
/* Make sure we've got one buffered packet from each open variant
* stream */
if (var->pb && !var->pkt.data) {
ret = av_read_frame(var->ctx, &var->pkt);
if (ret < 0) {
if (!url_feof(var->pb))
return ret;
reset_packet(&var->pkt);
}
}
/* 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 (first && changed)
av_log(s, AV_LOG_INFO, "Receiving %d variant streams\n", variants);
/* 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);
c->last_packet_dts = pkt->dts;
return 0;
}
/* No more packets - eof reached in all variant streams, close the
* current segments. */
for (i = 0; i < c->n_variants; i++) {
struct variant *var = c->variants[i];
if (var->pb) {
url_fclose(var->pb);
var->pb = NULL;
}
}
/* Indicate that we're opening the next segment, not opening a new
* variant stream in parallel, so we shouldn't try to skip ahead. */
first = 0;
c->cur_seq_no++;
reload:
if (!c->finished) {
/* If this is a live stream and target_duration has elapsed since
* the last playlist reload, reload the variant playlists now. */
int64_t now = av_gettime();
if (now - c->last_load_time >= c->target_duration*1000000) {
c->max_start_seq = 0;
c->min_end_seq = INT_MAX;
for (i = 0; i < c->n_variants; i++) {
struct variant *var = c->variants[i];
if (var->needed) {
if ((ret = parse_playlist(c, var->url, var, NULL)) < 0)
return ret;
c->max_start_seq = FFMAX(c->max_start_seq,
var->start_seq_no);
c->min_end_seq = FFMIN(c->min_end_seq,
var->start_seq_no + var->n_segments);
}
}
}
}
if (c->cur_seq_no < c->max_start_seq) {
av_log(NULL, AV_LOG_WARNING,
"skipping %d segments ahead, expired from playlists\n",
c->max_start_seq - c->cur_seq_no);
c->cur_seq_no = c->max_start_seq;
}
/* If more segments exit, open the next one */
if (c->cur_seq_no < c->min_end_seq)
goto start;
/* We've reached the end of the playlists - return eof if this is a
* non-live stream, wait until the next playlist reload if it is live. */
if (c->finished)
return AVERROR_EOF;
while (av_gettime() - c->last_load_time < c->target_duration*1000000) {
if (url_interrupt_cb())
return AVERROR(EINTR);
usleep(100*1000);
}
/* Enough time has elapsed since the last reload */
goto reload;
}
static int applehttp_close(AVFormatContext *s)
{
AppleHTTPContext *c = s->priv_data;
free_variant_list(c);
return 0;
}
static int applehttp_read_seek(AVFormatContext *s, int stream_index,
int64_t timestamp, int flags)
{
AppleHTTPContext *c = s->priv_data;
int pos = 0, i;
struct variant *var = c->variants[0];
if ((flags & AVSEEK_FLAG_BYTE) || !c->finished)
return AVERROR(ENOSYS);
/* Reset the variants */
c->last_packet_dts = AV_NOPTS_VALUE;
for (i = 0; i < c->n_variants; i++) {
struct variant *var = c->variants[i];
if (var->pb) {
url_fclose(var->pb);
var->pb = NULL;
}
av_free_packet(&var->pkt);
reset_packet(&var->pkt);
}
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);
/* Locate the segment that contains the target timestamp */
for (i = 0; i < var->n_segments; i++) {
if (timestamp >= pos && timestamp < pos + var->segments[i]->duration) {
c->cur_seq_no = var->start_seq_no + i;
return 0;
}
pos += var->segments[i]->duration;
}
return AVERROR(EIO);
}
static int applehttp_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_applehttp_demuxer = {
"applehttp",
NULL_IF_CONFIG_SMALL("Apple HTTP Live Streaming format"),
sizeof(AppleHTTPContext),
applehttp_probe,
applehttp_read_header,
applehttp_read_packet,
applehttp_close,
applehttp_read_seek,
};