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shaka-packager/packager/hls/base/media_playlist.cc

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// Copyright 2016 Google Inc. All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file or at
// https://developers.google.com/open-source/licenses/bsd
#include "packager/hls/base/media_playlist.h"
#include <inttypes.h>
#include <algorithm>
#include <cmath>
#include <memory>
#include "packager/base/logging.h"
#include "packager/base/strings/string_number_conversions.h"
#include "packager/base/strings/stringprintf.h"
#include "packager/file/file.h"
#include "packager/hls/base/tag.h"
#include "packager/media/base/language_utils.h"
#include "packager/version/version.h"
namespace shaka {
namespace hls {
namespace {
uint32_t GetTimeScale(const MediaInfo& media_info) {
if (media_info.has_reference_time_scale())
return media_info.reference_time_scale();
if (media_info.has_video_info())
return media_info.video_info().time_scale();
if (media_info.has_audio_info())
return media_info.audio_info().time_scale();
return 0u;
}
void AppendExtXMap(const MediaInfo& media_info, std::string* out) {
if (media_info.has_init_segment_name()) {
Tag tag("#EXT-X-MAP", out);
tag.AddQuotedString("URI", media_info.init_segment_name().data());
out->append("\n");
} else if (media_info.has_media_file_name() && media_info.has_init_range()) {
// It only makes sense for single segment media to have EXT-X-MAP if
// there is init_range.
Tag tag("#EXT-X-MAP", out);
tag.AddQuotedString("URI", media_info.media_file_name().data());
if (media_info.has_init_range()) {
const uint64_t begin = media_info.init_range().begin();
const uint64_t end = media_info.init_range().end();
const uint64_t length = end - begin + 1;
tag.AddQuotedNumberPair("BYTERANGE", length, '@', begin);
}
out->append("\n");
} else {
// This media info does not need an ext-x-map tag.
}
}
std::string CreatePlaylistHeader(
const MediaInfo& media_info,
uint32_t target_duration,
HlsPlaylistType type,
MediaPlaylist::MediaPlaylistStreamType stream_type,
int media_sequence_number,
int discontinuity_sequence_number) {
const std::string version = GetPackagerVersion();
std::string version_line;
if (!version.empty()) {
version_line =
base::StringPrintf("## Generated with %s version %s\n",
GetPackagerProjectUrl().c_str(), version.c_str());
}
// 6 is required for EXT-X-MAP without EXT-X-I-FRAMES-ONLY.
std::string header = base::StringPrintf(
"#EXTM3U\n"
"#EXT-X-VERSION:6\n"
"%s"
"#EXT-X-TARGETDURATION:%d\n",
version_line.c_str(), target_duration);
switch (type) {
case HlsPlaylistType::kVod:
header += "#EXT-X-PLAYLIST-TYPE:VOD\n";
break;
case HlsPlaylistType::kEvent:
header += "#EXT-X-PLAYLIST-TYPE:EVENT\n";
break;
case HlsPlaylistType::kLive:
if (media_sequence_number > 0) {
base::StringAppendF(&header, "#EXT-X-MEDIA-SEQUENCE:%d\n",
media_sequence_number);
}
if (discontinuity_sequence_number > 0) {
base::StringAppendF(&header, "#EXT-X-DISCONTINUITY-SEQUENCE:%d\n",
discontinuity_sequence_number);
}
break;
default:
NOTREACHED() << "Unexpected MediaPlaylistType " << static_cast<int>(type);
}
if (stream_type ==
MediaPlaylist::MediaPlaylistStreamType::kVideoIFramesOnly) {
base::StringAppendF(&header, "#EXT-X-I-FRAMES-ONLY\n");
}
// Put EXT-X-MAP at the end since the rest of the playlist is about the
// segment and key info.
AppendExtXMap(media_info, &header);
return header;
}
class SegmentInfoEntry : public HlsEntry {
public:
// If |use_byte_range| true then this will append EXT-X-BYTERANGE
// after EXTINF.
// It uses |previous_segment_end_offset| to determine if it has to also
// specify the start byte offset in the tag.
// |duration| is duration in seconds.
SegmentInfoEntry(const std::string& file_name,
double start_time,
double duration,
bool use_byte_range,
uint64_t start_byte_offset,
uint64_t segment_file_size,
uint64_t previous_segment_end_offset);
std::string ToString() override;
double start_time() const { return start_time_; }
double duration() const { return duration_; }
private:
SegmentInfoEntry(const SegmentInfoEntry&) = delete;
SegmentInfoEntry& operator=(const SegmentInfoEntry&) = delete;
const std::string file_name_;
const double start_time_;
const double duration_;
const bool use_byte_range_;
const uint64_t start_byte_offset_;
const uint64_t segment_file_size_;
const uint64_t previous_segment_end_offset_;
};
SegmentInfoEntry::SegmentInfoEntry(const std::string& file_name,
double start_time,
double duration,
bool use_byte_range,
uint64_t start_byte_offset,
uint64_t segment_file_size,
uint64_t previous_segment_end_offset)
: HlsEntry(HlsEntry::EntryType::kExtInf),
file_name_(file_name),
start_time_(start_time),
duration_(duration),
use_byte_range_(use_byte_range),
start_byte_offset_(start_byte_offset),
segment_file_size_(segment_file_size),
previous_segment_end_offset_(previous_segment_end_offset) {}
std::string SegmentInfoEntry::ToString() {
std::string result = base::StringPrintf("#EXTINF:%.3f,", duration_);
if (use_byte_range_) {
base::StringAppendF(&result, "\n#EXT-X-BYTERANGE:%" PRIu64,
segment_file_size_);
if (previous_segment_end_offset_ + 1 != start_byte_offset_) {
base::StringAppendF(&result, "@%" PRIu64, start_byte_offset_);
}
}
base::StringAppendF(&result, "\n%s", file_name_.c_str());
return result;
}
class EncryptionInfoEntry : public HlsEntry {
public:
EncryptionInfoEntry(MediaPlaylist::EncryptionMethod method,
const std::string& url,
const std::string& key_id,
const std::string& iv,
const std::string& key_format,
const std::string& key_format_versions);
std::string ToString() override;
private:
EncryptionInfoEntry(const EncryptionInfoEntry&) = delete;
EncryptionInfoEntry& operator=(const EncryptionInfoEntry&) = delete;
const MediaPlaylist::EncryptionMethod method_;
const std::string url_;
const std::string key_id_;
const std::string iv_;
const std::string key_format_;
const std::string key_format_versions_;
};
EncryptionInfoEntry::EncryptionInfoEntry(MediaPlaylist::EncryptionMethod method,
const std::string& url,
const std::string& key_id,
const std::string& iv,
const std::string& key_format,
const std::string& key_format_versions)
: HlsEntry(HlsEntry::EntryType::kExtKey),
method_(method),
url_(url),
key_id_(key_id),
iv_(iv),
key_format_(key_format),
key_format_versions_(key_format_versions) {}
std::string EncryptionInfoEntry::ToString() {
std::string tag_string;
Tag tag("#EXT-X-KEY", &tag_string);
if (method_ == MediaPlaylist::EncryptionMethod::kSampleAes) {
tag.AddString("METHOD", "SAMPLE-AES");
} else if (method_ == MediaPlaylist::EncryptionMethod::kAes128) {
tag.AddString("METHOD", "AES-128");
} else if (method_ == MediaPlaylist::EncryptionMethod::kSampleAesCenc) {
tag.AddString("METHOD", "SAMPLE-AES-CTR");
} else {
DCHECK(method_ == MediaPlaylist::EncryptionMethod::kNone);
tag.AddString("METHOD", "NONE");
}
tag.AddQuotedString("URI", url_);
if (!key_id_.empty()) {
tag.AddString("KEYID", key_id_);
}
if (!iv_.empty()) {
tag.AddString("IV", iv_);
}
if (!key_format_versions_.empty()) {
tag.AddQuotedString("KEYFORMATVERSIONS", key_format_versions_);
}
if (!key_format_.empty()) {
tag.AddQuotedString("KEYFORMAT", key_format_);
}
return tag_string;
}
class DiscontinuityEntry : public HlsEntry {
public:
DiscontinuityEntry();
std::string ToString() override;
private:
DiscontinuityEntry(const DiscontinuityEntry&) = delete;
DiscontinuityEntry& operator=(const DiscontinuityEntry&) = delete;
};
DiscontinuityEntry::DiscontinuityEntry()
: HlsEntry(HlsEntry::EntryType::kExtDiscontinuity) {}
std::string DiscontinuityEntry::ToString() {
return "#EXT-X-DISCONTINUITY";
}
class PlacementOpportunityEntry : public HlsEntry {
public:
PlacementOpportunityEntry();
std::string ToString() override;
private:
PlacementOpportunityEntry(const PlacementOpportunityEntry&) = delete;
PlacementOpportunityEntry& operator=(const PlacementOpportunityEntry&) =
delete;
};
PlacementOpportunityEntry::PlacementOpportunityEntry()
: HlsEntry(HlsEntry::EntryType::kExtPlacementOpportunity) {}
std::string PlacementOpportunityEntry::ToString() {
return "#EXT-X-PLACEMENT-OPPORTUNITY";
}
double LatestSegmentStartTime(
const std::list<std::unique_ptr<HlsEntry>>& entries) {
DCHECK(!entries.empty());
for (auto iter = entries.rbegin(); iter != entries.rend(); ++iter) {
if (iter->get()->type() == HlsEntry::EntryType::kExtInf) {
const SegmentInfoEntry* segment_info =
reinterpret_cast<SegmentInfoEntry*>(iter->get());
return segment_info->start_time();
}
}
return 0.0;
}
} // namespace
HlsEntry::HlsEntry(HlsEntry::EntryType type) : type_(type) {}
HlsEntry::~HlsEntry() {}
MediaPlaylist::MediaPlaylist(HlsPlaylistType playlist_type,
double time_shift_buffer_depth,
const std::string& file_name,
const std::string& name,
const std::string& group_id)
: playlist_type_(playlist_type),
time_shift_buffer_depth_(time_shift_buffer_depth),
file_name_(file_name),
name_(name),
group_id_(group_id) {}
MediaPlaylist::~MediaPlaylist() {}
void MediaPlaylist::SetStreamTypeForTesting(
MediaPlaylistStreamType stream_type) {
stream_type_ = stream_type;
}
void MediaPlaylist::SetCodecForTesting(const std::string& codec) {
codec_ = codec;
}
bool MediaPlaylist::SetMediaInfo(const MediaInfo& media_info) {
const uint32_t time_scale = GetTimeScale(media_info);
if (time_scale == 0) {
LOG(ERROR) << "MediaInfo does not contain a valid timescale.";
return false;
}
if (media_info.has_video_info()) {
stream_type_ = MediaPlaylistStreamType::kVideo;
codec_ = media_info.video_info().codec();
} else if (media_info.has_audio_info()) {
stream_type_ = MediaPlaylistStreamType::kAudio;
codec_ = media_info.audio_info().codec();
} else {
stream_type_ = MediaPlaylistStreamType::kSubtitle;
codec_ = media_info.text_info().format();
}
time_scale_ = time_scale;
media_info_ = media_info;
use_byte_range_ = !media_info_.has_segment_template();
return true;
}
void MediaPlaylist::AddSegment(const std::string& file_name,
uint64_t start_time,
uint64_t duration,
uint64_t start_byte_offset,
uint64_t size) {
if (stream_type_ == MediaPlaylistStreamType::kVideoIFramesOnly) {
if (key_frames_.empty())
return;
// Skip the last entry as the duration of the key frames are defined by the
// next key frame, which we don't know yet.
for (auto iter = key_frames_.begin(); iter != std::prev(key_frames_.end());
++iter) {
const std::string& segment_file_name =
iter->segment_file_name.empty() ? file_name : iter->segment_file_name;
AddSegmentInfoEntry(segment_file_name, iter->timestamp, iter->duration,
iter->start_byte_offset, iter->size);
}
key_frames_.erase(key_frames_.begin(), std::prev(key_frames_.end()));
KeyFrameInfo& key_frame = key_frames_.front();
key_frame.segment_file_name = file_name;
key_frame.duration = start_time + duration - key_frame.timestamp;
return;
}
return AddSegmentInfoEntry(file_name, start_time, duration, start_byte_offset,
size);
}
void MediaPlaylist::AddKeyFrame(uint64_t timestamp,
uint64_t start_byte_offset,
uint64_t size) {
if (stream_type_ != MediaPlaylistStreamType::kVideoIFramesOnly) {
if (stream_type_ != MediaPlaylistStreamType::kVideo) {
LOG(WARNING)
<< "I-Frames Only playlist applies to video renditions only.";
return;
}
stream_type_ = MediaPlaylistStreamType::kVideoIFramesOnly;
use_byte_range_ = true;
}
if (!key_frames_.empty()) {
key_frames_.back().duration = timestamp - key_frames_.back().timestamp;
}
key_frames_.push_back({timestamp, start_byte_offset, size});
}
void MediaPlaylist::AddEncryptionInfo(MediaPlaylist::EncryptionMethod method,
const std::string& url,
const std::string& key_id,
const std::string& iv,
const std::string& key_format,
const std::string& key_format_versions) {
if (!inserted_discontinuity_tag_) {
// Insert discontinuity tag only for the first EXT-X-KEY, only if there
// are non-encrypted media segments.
if (!entries_.empty())
entries_.emplace_back(new DiscontinuityEntry());
inserted_discontinuity_tag_ = true;
}
entries_.emplace_back(new EncryptionInfoEntry(
method, url, key_id, iv, key_format, key_format_versions));
}
void MediaPlaylist::AddPlacementOpportunity() {
entries_.emplace_back(new PlacementOpportunityEntry());
}
bool MediaPlaylist::WriteToFile(const std::string& file_path) {
if (!key_frames_.empty() && playlist_type_ == HlsPlaylistType::kVod) {
// Flush remaining key frames. This assumes |WriteToFile| is only called
// once at the end of the file in VOD.
CHECK_EQ(key_frames_.size(), 1u);
const KeyFrameInfo& key_frame = key_frames_.front();
AddSegmentInfoEntry(key_frame.segment_file_name, key_frame.timestamp,
key_frame.duration, key_frame.start_byte_offset,
key_frame.size);
key_frames_.clear();
}
if (!target_duration_set_) {
SetTargetDuration(ceil(GetLongestSegmentDuration()));
}
std::string content = CreatePlaylistHeader(
media_info_, target_duration_, playlist_type_, stream_type_,
media_sequence_number_, discontinuity_sequence_number_);
for (const auto& entry : entries_)
base::StringAppendF(&content, "%s\n", entry->ToString().c_str());
if (playlist_type_ == HlsPlaylistType::kVod) {
content += "#EXT-X-ENDLIST\n";
}
if (!File::WriteFileAtomically(file_path.c_str(), content)) {
LOG(ERROR) << "Failed to write playlist to: " << file_path;
return false;
}
return true;
}
uint64_t MediaPlaylist::Bitrate() const {
if (media_info_.has_bandwidth())
return media_info_.bandwidth();
return max_bitrate_;
}
double MediaPlaylist::GetLongestSegmentDuration() const {
return longest_segment_duration_;
}
void MediaPlaylist::SetTargetDuration(uint32_t target_duration) {
if (target_duration_set_) {
if (target_duration_ == target_duration)
return;
VLOG(1) << "Updating target duration from " << target_duration << " to "
<< target_duration_;
}
target_duration_ = target_duration;
target_duration_set_ = true;
}
// Duplicated from MpdUtils because:
// 1. MpdUtils header depends on libxml header, which is not in the deps here
// 2. GetLanguage depends on MediaInfo from packager/mpd/
// 3. Moving GetLanguage to LanguageUtils would create a a media => mpd dep.
// TODO: fix this dependency situation and factor this out to a common location
std::string MediaPlaylist::GetLanguage() const {
std::string lang;
if (media_info_.has_audio_info()) {
lang = media_info_.audio_info().language();
} else if (media_info_.has_text_info()) {
lang = media_info_.text_info().language();
}
return LanguageToShortestForm(lang);
}
int MediaPlaylist::GetNumChannels() const {
return media_info_.audio_info().num_channels();
}
bool MediaPlaylist::GetDisplayResolution(uint32_t* width,
uint32_t* height) const {
DCHECK(width);
DCHECK(height);
if (media_info_.has_video_info()) {
const double pixel_aspect_ratio =
media_info_.video_info().pixel_height() > 0
? static_cast<double>(media_info_.video_info().pixel_width()) /
media_info_.video_info().pixel_height()
: 1.0;
*width = static_cast<uint32_t>(media_info_.video_info().width() *
pixel_aspect_ratio);
*height = media_info_.video_info().height();
return true;
}
return false;
}
void MediaPlaylist::AddSegmentInfoEntry(const std::string& segment_file_name,
uint64_t start_time,
uint64_t duration,
uint64_t start_byte_offset,
uint64_t size) {
if (time_scale_ == 0) {
LOG(WARNING) << "Timescale is not set and the duration for " << duration
<< " cannot be calculated. The output will be wrong.";
entries_.emplace_back(new SegmentInfoEntry(
segment_file_name, 0.0, 0.0, use_byte_range_, start_byte_offset, size,
previous_segment_end_offset_));
return;
}
const double start_time_seconds =
static_cast<double>(start_time) / time_scale_;
const double segment_duration_seconds =
static_cast<double>(duration) / time_scale_;
if (segment_duration_seconds > longest_segment_duration_)
longest_segment_duration_ = segment_duration_seconds;
const int kBitsInByte = 8;
const uint64_t bitrate = kBitsInByte * size / segment_duration_seconds;
max_bitrate_ = std::max(max_bitrate_, bitrate);
entries_.emplace_back(new SegmentInfoEntry(
segment_file_name, start_time_seconds, segment_duration_seconds,
use_byte_range_, start_byte_offset, size, previous_segment_end_offset_));
previous_segment_end_offset_ = start_byte_offset + size - 1;
SlideWindow();
}
void MediaPlaylist::SlideWindow() {
DCHECK(!entries_.empty());
if (time_shift_buffer_depth_ <= 0.0 ||
playlist_type_ != HlsPlaylistType::kLive) {
return;
}
DCHECK_GT(time_scale_, 0u);
// The start time of the latest segment is considered the current_play_time,
// and this should guarantee that the latest segment will stay in the list.
const double current_play_time = LatestSegmentStartTime(entries_);
if (current_play_time <= time_shift_buffer_depth_)
return;
const double timeshift_limit = current_play_time - time_shift_buffer_depth_;
// Temporary list to hold the EXT-X-KEYs. For example, this allows us to
// remove <3> without removing <1> and <2> below (<1> and <2> are moved to the
// temporary list and added back later).
// #EXT-X-KEY <1>
// #EXT-X-KEY <2>
// #EXTINF <3>
// #EXTINF <4>
std::list<std::unique_ptr<HlsEntry>> ext_x_keys;
// Consecutive key entries are either fully removed or not removed at all.
// Keep track of entry types so we know if it is consecutive key entries.
HlsEntry::EntryType prev_entry_type = HlsEntry::EntryType::kExtInf;
std::list<std::unique_ptr<HlsEntry>>::iterator last = entries_.begin();
size_t num_segments_removed = 0;
for (; last != entries_.end(); ++last) {
HlsEntry::EntryType entry_type = last->get()->type();
if (entry_type == HlsEntry::EntryType::kExtKey) {
if (prev_entry_type != HlsEntry::EntryType::kExtKey)
ext_x_keys.clear();
ext_x_keys.push_back(std::move(*last));
} else if (entry_type == HlsEntry::EntryType::kExtDiscontinuity) {
++discontinuity_sequence_number_;
} else {
DCHECK_EQ(entry_type, HlsEntry::EntryType::kExtInf);
const SegmentInfoEntry* segment_info =
reinterpret_cast<SegmentInfoEntry*>(last->get());
const double last_segment_end_time =
segment_info->start_time() + segment_info->duration();
if (timeshift_limit < last_segment_end_time)
break;
++num_segments_removed;
}
prev_entry_type = entry_type;
}
entries_.erase(entries_.begin(), last);
// Add key entries back.
entries_.insert(entries_.begin(), std::make_move_iterator(ext_x_keys.begin()),
std::make_move_iterator(ext_x_keys.end()));
media_sequence_number_ += num_segments_removed;
}
} // namespace hls
} // namespace shaka
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