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shaka-packager/packager/mpd/base/representation.cc

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// Copyright 2017 Google LLC. 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/mpd/base/representation.h>
#include <algorithm>
#include <absl/flags/declare.h>
#include <absl/log/check.h>
#include <absl/log/log.h>
#include <absl/strings/str_format.h>
#include <packager/file.h>
#include <packager/macros/logging.h>
#include <packager/media/base/muxer_util.h>
#include <packager/mpd/base/mpd_options.h>
#include <packager/mpd/base/mpd_utils.h>
#include <packager/mpd/base/xml/xml_node.h>
namespace shaka {
namespace {
std::string GetMimeType(const std::string& prefix,
MediaInfo::ContainerType container_type) {
switch (container_type) {
case MediaInfo::CONTAINER_MP4:
return prefix + "/mp4";
case MediaInfo::CONTAINER_MPEG2_TS:
// NOTE: DASH MPD spec uses lowercase but RFC3555 says uppercase.
return prefix + "/MP2T";
case MediaInfo::CONTAINER_WEBM:
return prefix + "/webm";
default:
break;
}
// Unsupported container types should be rejected/handled by the caller.
LOG(ERROR) << "Unrecognized container type: " << container_type;
return std::string();
}
// Check whether the video info has width and height.
// DASH IOP also requires several other fields for video representations, namely
// width, height, framerate, and sar.
bool HasRequiredVideoFields(const MediaInfo_VideoInfo& video_info) {
if (!video_info.has_height() || !video_info.has_width()) {
LOG(ERROR)
<< "Width and height are required fields for generating a valid MPD.";
return false;
}
// These fields are not required for a valid MPD, but required for DASH IOP
// compliant MPD. MpdBuilder can keep generating MPDs without these fields.
LOG_IF(WARNING, !video_info.has_time_scale())
<< "Video info does not contain timescale required for "
"calculating framerate. @frameRate is required for DASH IOP.";
LOG_IF(WARNING, !video_info.has_pixel_width())
<< "Video info does not contain pixel_width to calculate the sample "
"aspect ratio required for DASH IOP.";
LOG_IF(WARNING, !video_info.has_pixel_height())
<< "Video info does not contain pixel_height to calculate the sample "
"aspect ratio required for DASH IOP.";
return true;
}
int32_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();
}
LOG(WARNING) << "No timescale specified, using 1 as timescale.";
return 1;
}
} // namespace
Representation::Representation(
const MediaInfo& media_info,
const MpdOptions& mpd_options,
uint32_t id,
std::unique_ptr<RepresentationStateChangeListener> state_change_listener)
: media_info_(media_info),
id_(id),
mpd_options_(mpd_options),
state_change_listener_(std::move(state_change_listener)),
allow_approximate_segment_timeline_(
// TODO(kqyang): Need a better check. $Time is legitimate but not a
// template.
media_info.segment_template().find("$Time") == std::string::npos &&
mpd_options_.mpd_params.allow_approximate_segment_timeline) {}
Representation::Representation(
const Representation& representation,
std::unique_ptr<RepresentationStateChangeListener> state_change_listener)
: Representation(representation.media_info_,
representation.mpd_options_,
representation.id_,
std::move(state_change_listener)) {
mime_type_ = representation.mime_type_;
codecs_ = representation.codecs_;
start_number_ = representation.start_number_;
for (const SegmentInfo& segment_info : representation.segment_infos_)
start_number_ += segment_info.repeat + 1;
}
Representation::~Representation() {}
bool Representation::Init() {
if (!AtLeastOneTrue(media_info_.has_video_info(),
media_info_.has_audio_info(),
media_info_.has_text_info())) {
// This is an error. Segment information can be in AdaptationSet, Period, or
// MPD but the interface does not provide a way to set them.
// See 5.3.9.1 ISO 23009-1:2012 for segment info.
LOG(ERROR) << "Representation needs one of video, audio, or text.";
return false;
}
if (MoreThanOneTrue(media_info_.has_video_info(),
media_info_.has_audio_info(),
media_info_.has_text_info())) {
LOG(ERROR) << "Only one of VideoInfo, AudioInfo, or TextInfo can be set.";
return false;
}
if (media_info_.container_type() == MediaInfo::CONTAINER_UNKNOWN) {
LOG(ERROR) << "'container_type' in MediaInfo cannot be CONTAINER_UNKNOWN.";
return false;
}
if (media_info_.has_video_info()) {
mime_type_ = GetVideoMimeType();
if (!HasRequiredVideoFields(media_info_.video_info())) {
LOG(ERROR) << "Missing required fields to create a video Representation.";
return false;
}
} else if (media_info_.has_audio_info()) {
mime_type_ = GetAudioMimeType();
} else if (media_info_.has_text_info()) {
mime_type_ = GetTextMimeType();
}
if (mime_type_.empty())
return false;
codecs_ = GetCodecs(media_info_);
return true;
}
void Representation::AddContentProtectionElement(
const ContentProtectionElement& content_protection_element) {
content_protection_elements_.push_back(content_protection_element);
RemoveDuplicateAttributes(&content_protection_elements_.back());
}
void Representation::UpdateContentProtectionPssh(const std::string& drm_uuid,
const std::string& pssh) {
UpdateContentProtectionPsshHelper(drm_uuid, pssh,
&content_protection_elements_);
}
void Representation::AddNewSegment(int64_t start_time,
int64_t duration,
uint64_t size) {
if (start_time == 0 && duration == 0) {
LOG(WARNING) << "Got segment with start_time and duration == 0. Ignoring.";
return;
}
// In order for the oldest segment to be accessible for at least
// |time_shift_buffer_depth| seconds, the latest segment should not be in the
// sliding window since the player could be playing any part of the latest
// segment. So the current segment duration is added to the sum of segment
// durations (in the manifest/playlist) after sliding the window.
SlideWindow();
if (state_change_listener_)
state_change_listener_->OnNewSegmentForRepresentation(start_time, duration);
AddSegmentInfo(start_time, duration);
// Only update the buffer depth and bandwidth estimator when the full segment
// is completed. In the low latency case, only the first chunk in the segment
// has been written at this point. Therefore, we must wait until the entire
// segment has been written before updating buffer depth and bandwidth
// estimator.
if (!mpd_options_.mpd_params.low_latency_dash_mode) {
current_buffer_depth_ += segment_infos_.back().duration;
bandwidth_estimator_.AddBlock(size, static_cast<double>(duration) /
media_info_.reference_time_scale());
}
}
void Representation::UpdateCompletedSegment(int64_t duration, uint64_t size) {
if (!mpd_options_.mpd_params.low_latency_dash_mode) {
LOG(WARNING)
<< "UpdateCompletedSegment is only applicable to low latency mode.";
return;
}
UpdateSegmentInfo(duration);
current_buffer_depth_ += segment_infos_.back().duration;
bandwidth_estimator_.AddBlock(
size, static_cast<double>(duration) / media_info_.reference_time_scale());
}
void Representation::SetSampleDuration(int32_t frame_duration) {
// Sample duration is used to generate approximate SegmentTimeline.
// Text is required to have exactly the same segment duration.
if (media_info_.has_audio_info() || media_info_.has_video_info())
frame_duration_ = frame_duration;
if (media_info_.has_video_info()) {
media_info_.mutable_video_info()->set_frame_duration(frame_duration);
if (state_change_listener_) {
state_change_listener_->OnSetFrameRateForRepresentation(
frame_duration, media_info_.video_info().time_scale());
}
}
}
void Representation::SetSegmentDuration() {
int64_t sd = mpd_options_.mpd_params.target_segment_duration *
media_info_.reference_time_scale();
if (sd <= 0)
return;
media_info_.set_segment_duration(sd);
}
const MediaInfo& Representation::GetMediaInfo() const {
return media_info_;
}
// Uses info in |media_info_| and |content_protection_elements_| to create a
// "Representation" node.
// MPD schema has strict ordering. The following must be done in order.
// AddVideoInfo() (possibly adds FramePacking elements), AddAudioInfo() (Adds
// AudioChannelConfig elements), AddContentProtectionElements*(), and
// AddVODOnlyInfo() (Adds segment info).
std::optional<xml::XmlNode> Representation::GetXml() {
if (!HasRequiredMediaInfoFields()) {
LOG(ERROR) << "MediaInfo missing required fields.";
return std::nullopt;
}
const uint64_t bandwidth = media_info_.has_bandwidth()
? media_info_.bandwidth()
: bandwidth_estimator_.Max();
DCHECK(!(HasVODOnlyFields(media_info_) && HasLiveOnlyFields(media_info_)));
xml::RepresentationXmlNode representation;
// Mandatory fields for Representation.
if (!representation.SetId(id_) ||
!representation.SetIntegerAttribute("bandwidth", bandwidth) ||
!(codecs_.empty() ||
representation.SetStringAttribute("codecs", codecs_)) ||
!representation.SetStringAttribute("mimeType", mime_type_)) {
return std::nullopt;
}
const bool has_video_info = media_info_.has_video_info();
const bool has_audio_info = media_info_.has_audio_info();
if (has_video_info &&
!representation.AddVideoInfo(
media_info_.video_info(),
!(output_suppression_flags_ & kSuppressWidth),
!(output_suppression_flags_ & kSuppressHeight),
!(output_suppression_flags_ & kSuppressFrameRate))) {
LOG(ERROR) << "Failed to add video info to Representation XML.";
return std::nullopt;
}
if (has_audio_info &&
!representation.AddAudioInfo(media_info_.audio_info())) {
LOG(ERROR) << "Failed to add audio info to Representation XML.";
return std::nullopt;
}
if (!representation.AddContentProtectionElements(
content_protection_elements_)) {
return std::nullopt;
}
if (HasVODOnlyFields(media_info_) &&
!representation.AddVODOnlyInfo(
media_info_, mpd_options_.mpd_params.use_segment_list,
mpd_options_.mpd_params.target_segment_duration)) {
LOG(ERROR) << "Failed to add VOD info.";
return std::nullopt;
}
if (HasLiveOnlyFields(media_info_) &&
!representation.AddLiveOnlyInfo(
media_info_, segment_infos_, start_number_,
mpd_options_.mpd_params.low_latency_dash_mode)) {
LOG(ERROR) << "Failed to add Live info.";
return std::nullopt;
}
// TODO(rkuroiwa): It is likely that all representations have the exact same
// SegmentTemplate. Optimize and propagate the tag up to AdaptationSet level.
output_suppression_flags_ = 0;
return representation;
}
void Representation::SuppressOnce(SuppressFlag flag) {
output_suppression_flags_ |= flag;
}
void Representation::SetPresentationTimeOffset(
double presentation_time_offset) {
int64_t pto = presentation_time_offset * media_info_.reference_time_scale();
if (pto <= 0)
return;
media_info_.set_presentation_time_offset(pto);
}
void Representation::SetAvailabilityTimeOffset() {
// Adjust the frame duration to units of seconds to match target segment
// duration.
const double frame_duration_sec =
(double)frame_duration_ / (double)media_info_.reference_time_scale();
// availabilityTimeOffset = segment duration - chunk duration.
// Here, the frame duration is equivalent to the sample duration,
// see Representation::SetSampleDuration(uint32_t frame_duration).
// By definition, each chunk will contain only one sample;
// thus, chunk_duration = sample_duration = frame_duration.
const double ato =
mpd_options_.mpd_params.target_segment_duration - frame_duration_sec;
if (ato <= 0)
return;
media_info_.set_availability_time_offset(ato);
}
bool Representation::GetStartAndEndTimestamps(
double* start_timestamp_seconds,
double* end_timestamp_seconds) const {
if (segment_infos_.empty())
return false;
if (start_timestamp_seconds) {
*start_timestamp_seconds =
static_cast<double>(segment_infos_.begin()->start_time) /
GetTimeScale(media_info_);
}
if (end_timestamp_seconds) {
*end_timestamp_seconds =
static_cast<double>(segment_infos_.rbegin()->start_time +
segment_infos_.rbegin()->duration *
(segment_infos_.rbegin()->repeat + 1)) /
GetTimeScale(media_info_);
}
return true;
}
bool Representation::HasRequiredMediaInfoFields() const {
if (HasVODOnlyFields(media_info_) && HasLiveOnlyFields(media_info_)) {
LOG(ERROR) << "MediaInfo cannot have both VOD and Live fields.";
return false;
}
if (!media_info_.has_container_type()) {
LOG(ERROR) << "MediaInfo missing required field: container_type.";
return false;
}
return true;
}
void Representation::AddSegmentInfo(int64_t start_time, int64_t duration) {
const uint64_t kNoRepeat = 0;
const int64_t adjusted_duration = AdjustDuration(duration);
if (!segment_infos_.empty()) {
// Contiguous segment.
const SegmentInfo& previous = segment_infos_.back();
const int64_t previous_segment_end_time =
previous.start_time + previous.duration * (previous.repeat + 1);
// Make it continuous if the segment start time is close to previous segment
// end time.
if (ApproximiatelyEqual(previous_segment_end_time, start_time)) {
const int64_t segment_end_time_for_same_duration =
previous_segment_end_time + previous.duration;
const int64_t actual_segment_end_time = start_time + duration;
// Consider the segments having identical duration if the segment end time
// is close to calculated segment end time by assuming identical duration.
if (ApproximiatelyEqual(segment_end_time_for_same_duration,
actual_segment_end_time)) {
++segment_infos_.back().repeat;
} else {
segment_infos_.push_back(
{previous_segment_end_time,
actual_segment_end_time - previous_segment_end_time, kNoRepeat});
}
return;
}
// A gap since previous.
const int64_t kRoundingErrorGrace = 5;
if (previous_segment_end_time + kRoundingErrorGrace < start_time) {
LOG(WARNING) << RepresentationAsString() << " Found a gap of size "
<< (start_time - previous_segment_end_time)
<< " > kRoundingErrorGrace (" << kRoundingErrorGrace
<< "). The new segment starts at " << start_time
<< " but the previous segment ends at "
<< previous_segment_end_time << ".";
}
// No overlapping segments.
if (start_time < previous_segment_end_time - kRoundingErrorGrace) {
LOG(WARNING)
<< RepresentationAsString()
<< " Segments should not be overlapping. The new segment starts at "
<< start_time << " but the previous segment ends at "
<< previous_segment_end_time << ".";
}
}
segment_infos_.push_back({start_time, adjusted_duration, kNoRepeat});
}
void Representation::UpdateSegmentInfo(int64_t duration) {
if (!segment_infos_.empty()) {
// Update the duration in the current segment.
segment_infos_.back().duration = duration;
}
}
bool Representation::ApproximiatelyEqual(int64_t time1, int64_t time2) const {
if (!allow_approximate_segment_timeline_)
return time1 == time2;
// It is not always possible to align segment duration to target duration
// exactly. For example, for AAC with sampling rate of 44100, there are always
// 1024 audio samples per frame, so the frame duration is 1024/44100. For a
// target duration of 2 seconds, the closest segment duration would be 1.984
// or 2.00533.
// An arbitrary error threshold cap. This makes sure that the error is not too
// large for large samples.
const double kErrorThresholdSeconds = 0.05;
// So we consider two times equal if they differ by less than one sample.
const int32_t error_threshold =
std::min(frame_duration_,
static_cast<int32_t>(kErrorThresholdSeconds *
media_info_.reference_time_scale()));
return std::abs(time1 - time2) <= error_threshold;
}
int64_t Representation::AdjustDuration(int64_t duration) const {
if (!allow_approximate_segment_timeline_)
return duration;
const int64_t scaled_target_duration =
mpd_options_.mpd_params.target_segment_duration *
media_info_.reference_time_scale();
return ApproximiatelyEqual(scaled_target_duration, duration)
? scaled_target_duration
: duration;
}
void Representation::SlideWindow() {
if (mpd_options_.mpd_params.time_shift_buffer_depth <= 0.0 ||
mpd_options_.mpd_type == MpdType::kStatic)
return;
const int32_t time_scale = GetTimeScale(media_info_);
DCHECK_GT(time_scale, 0);
const int64_t time_shift_buffer_depth = static_cast<int64_t>(
mpd_options_.mpd_params.time_shift_buffer_depth * time_scale);
if (current_buffer_depth_ <= time_shift_buffer_depth)
return;
std::list<SegmentInfo>::iterator first = segment_infos_.begin();
std::list<SegmentInfo>::iterator last = first;
for (; last != segment_infos_.end(); ++last) {
// Remove the current segment only if it falls completely out of time shift
// buffer range.
while (last->repeat >= 0 &&
current_buffer_depth_ - last->duration >= time_shift_buffer_depth) {
current_buffer_depth_ -= last->duration;
RemoveOldSegment(&*last);
start_number_++;
}
if (last->repeat >= 0)
break;
}
segment_infos_.erase(first, last);
}
void Representation::RemoveOldSegment(SegmentInfo* segment_info) {
int64_t segment_start_time = segment_info->start_time;
segment_info->start_time += segment_info->duration;
segment_info->repeat--;
if (mpd_options_.mpd_params.preserved_segments_outside_live_window == 0)
return;
segments_to_be_removed_.push_back(
media::GetSegmentName(media_info_.segment_template(), segment_start_time,
start_number_ - 1, media_info_.bandwidth()));
while (segments_to_be_removed_.size() >
mpd_options_.mpd_params.preserved_segments_outside_live_window) {
VLOG(2) << "Deleting " << segments_to_be_removed_.front();
if (!File::Delete(segments_to_be_removed_.front().c_str())) {
LOG(WARNING) << "Failed to delete " << segments_to_be_removed_.front()
<< "; Will retry later.";
break;
}
segments_to_be_removed_.pop_front();
}
}
std::string Representation::GetVideoMimeType() const {
return GetMimeType("video", media_info_.container_type());
}
std::string Representation::GetAudioMimeType() const {
return GetMimeType("audio", media_info_.container_type());
}
std::string Representation::GetTextMimeType() const {
CHECK(media_info_.has_text_info());
if (media_info_.text_info().codec() == "ttml") {
switch (media_info_.container_type()) {
case MediaInfo::CONTAINER_TEXT:
return "application/ttml+xml";
case MediaInfo::CONTAINER_MP4:
return "application/mp4";
default:
LOG(ERROR) << "Failed to determine MIME type for TTML container: "
<< media_info_.container_type();
return "";
}
}
if (media_info_.text_info().codec() == "wvtt") {
if (media_info_.container_type() == MediaInfo::CONTAINER_TEXT) {
return "text/vtt";
} else if (media_info_.container_type() == MediaInfo::CONTAINER_MP4) {
return "application/mp4";
}
LOG(ERROR) << "Failed to determine MIME type for VTT container: "
<< media_info_.container_type();
return "";
}
LOG(ERROR) << "Cannot determine MIME type for format: "
<< media_info_.text_info().codec()
<< " container: " << media_info_.container_type();
return "";
}
std::string Representation::RepresentationAsString() const {
std::string s = absl::StrFormat("Representation (id=%d,", id_);
if (media_info_.has_video_info()) {
const MediaInfo_VideoInfo& video_info = media_info_.video_info();
absl::StrAppendFormat(&s, "codec='%s',width=%d,height=%d",
video_info.codec().c_str(), video_info.width(),
video_info.height());
} else if (media_info_.has_audio_info()) {
const MediaInfo_AudioInfo& audio_info = media_info_.audio_info();
absl::StrAppendFormat(
&s, "codec='%s',frequency=%d,language='%s'", audio_info.codec().c_str(),
audio_info.sampling_frequency(), audio_info.language().c_str());
} else if (media_info_.has_text_info()) {
const MediaInfo_TextInfo& text_info = media_info_.text_info();
absl::StrAppendFormat(&s, "codec='%s',language='%s'",
text_info.codec().c_str(),
text_info.language().c_str());
}
absl::StrAppendFormat(&s, ")");
return s;
}
} // namespace shaka
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