433 lines
14 KiB
C++
433 lines
14 KiB
C++
// Copyright 2014 Google Inc. All rights reserved.
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//
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file or at
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// https://developers.google.com/open-source/licenses/bsd
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#include "packager/mpd/base/mpd_builder.h"
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#include <algorithm>
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#include "packager/base/files/file_path.h"
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#include "packager/base/logging.h"
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#include "packager/base/optional.h"
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#include "packager/base/strings/string_number_conversions.h"
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#include "packager/base/strings/stringprintf.h"
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#include "packager/base/synchronization/lock.h"
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#include "packager/base/time/default_clock.h"
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#include "packager/base/time/time.h"
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#include "packager/mpd/base/adaptation_set.h"
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#include "packager/mpd/base/mpd_utils.h"
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#include "packager/mpd/base/period.h"
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#include "packager/mpd/base/representation.h"
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#include "packager/mpd/base/xml/xml_node.h"
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#include "packager/version/version.h"
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namespace shaka {
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using base::FilePath;
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using xml::XmlNode;
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namespace {
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void AddMpdNameSpaceInfo(XmlNode* mpd) {
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DCHECK(mpd);
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static const char kXmlNamespace[] = "urn:mpeg:dash:schema:mpd:2011";
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static const char kXmlNamespaceXsi[] =
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"http://www.w3.org/2001/XMLSchema-instance";
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static const char kXmlNamespaceXlink[] = "http://www.w3.org/1999/xlink";
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static const char kDashSchemaMpd2011[] =
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"urn:mpeg:dash:schema:mpd:2011 DASH-MPD.xsd";
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static const char kCencNamespace[] = "urn:mpeg:cenc:2013";
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mpd->SetStringAttribute("xmlns", kXmlNamespace);
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mpd->SetStringAttribute("xmlns:xsi", kXmlNamespaceXsi);
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mpd->SetStringAttribute("xmlns:xlink", kXmlNamespaceXlink);
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mpd->SetStringAttribute("xsi:schemaLocation", kDashSchemaMpd2011);
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mpd->SetStringAttribute("xmlns:cenc", kCencNamespace);
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}
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bool Positive(double d) {
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return d > 0.0;
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}
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// Return current time in XML DateTime format. The value is in UTC, so the
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// string ends with a 'Z'.
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std::string XmlDateTimeNowWithOffset(
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int32_t offset_seconds,
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base::Clock* clock) {
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base::Time time = clock->Now();
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time += base::TimeDelta::FromSeconds(offset_seconds);
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base::Time::Exploded time_exploded;
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time.UTCExplode(&time_exploded);
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return base::StringPrintf("%4d-%02d-%02dT%02d:%02d:%02dZ", time_exploded.year,
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time_exploded.month, time_exploded.day_of_month,
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time_exploded.hour, time_exploded.minute,
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time_exploded.second);
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}
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void SetIfPositive(const char* attr_name, double value, XmlNode* mpd) {
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if (Positive(value)) {
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mpd->SetStringAttribute(attr_name, SecondsToXmlDuration(value));
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}
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}
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std::string MakePathRelative(const std::string& media_path,
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const FilePath& parent_path) {
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FilePath relative_path;
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const FilePath child_path = FilePath::FromUTF8Unsafe(media_path);
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const bool is_child =
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parent_path.AppendRelativePath(child_path, &relative_path);
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if (!is_child)
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relative_path = child_path;
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return relative_path.NormalizePathSeparatorsTo('/').AsUTF8Unsafe();
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}
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// Spooky static initialization/cleanup of libxml.
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class LibXmlInitializer {
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public:
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LibXmlInitializer() : initialized_(false) {
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base::AutoLock lock(lock_);
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if (!initialized_) {
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xmlInitParser();
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initialized_ = true;
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}
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}
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~LibXmlInitializer() {
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base::AutoLock lock(lock_);
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if (initialized_) {
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xmlCleanupParser();
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initialized_ = false;
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}
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}
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private:
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base::Lock lock_;
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bool initialized_;
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DISALLOW_COPY_AND_ASSIGN(LibXmlInitializer);
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};
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} // namespace
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MpdBuilder::MpdBuilder(const MpdOptions& mpd_options)
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: mpd_options_(mpd_options), clock_(new base::DefaultClock()) {}
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MpdBuilder::~MpdBuilder() {}
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void MpdBuilder::AddBaseUrl(const std::string& base_url) {
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base_urls_.push_back(base_url);
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}
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Period* MpdBuilder::GetOrCreatePeriod(double start_time_in_seconds) {
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for (auto& period : periods_) {
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const double kPeriodTimeDriftThresholdInSeconds = 1.0;
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const bool match =
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std::fabs(period->start_time_in_seconds() - start_time_in_seconds) <
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kPeriodTimeDriftThresholdInSeconds;
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if (match)
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return period.get();
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}
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periods_.emplace_back(new Period(period_counter_.GetNext(),
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start_time_in_seconds, mpd_options_,
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&representation_counter_));
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return periods_.back().get();
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}
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bool MpdBuilder::ToString(std::string* output) {
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DCHECK(output);
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static LibXmlInitializer lib_xml_initializer;
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xml::scoped_xml_ptr<xmlDoc> doc(GenerateMpd());
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if (!doc)
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return false;
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static const int kNiceFormat = 1;
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int doc_str_size = 0;
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xmlChar* doc_str = nullptr;
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xmlDocDumpFormatMemoryEnc(doc.get(), &doc_str, &doc_str_size, "UTF-8",
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kNiceFormat);
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output->assign(doc_str, doc_str + doc_str_size);
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xmlFree(doc_str);
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// Cleanup, free the doc.
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doc.reset();
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return true;
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}
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xmlDocPtr MpdBuilder::GenerateMpd() {
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// Setup nodes.
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static const char kXmlVersion[] = "1.0";
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xml::scoped_xml_ptr<xmlDoc> doc(xmlNewDoc(BAD_CAST kXmlVersion));
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XmlNode mpd("MPD");
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// Add baseurls to MPD.
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for (const std::string& base_url : base_urls_) {
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XmlNode xml_base_url("BaseURL");
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xml_base_url.SetContent(base_url);
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if (!mpd.AddChild(xml_base_url.PassScopedPtr()))
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return nullptr;
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}
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bool output_period_duration = false;
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if (mpd_options_.mpd_type == MpdType::kStatic) {
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UpdatePeriodDurationAndPresentationTimestamp();
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// Only output period duration if there are more than one period. In the
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// case of only one period, Period@duration is redundant as it is identical
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// to Mpd Duration so the convention is not to output Period@duration.
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output_period_duration = periods_.size() > 1;
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}
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for (const auto& period : periods_) {
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xml::scoped_xml_ptr<xmlNode> period_node(
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period->GetXml(output_period_duration));
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if (!period_node || !mpd.AddChild(std::move(period_node)))
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return nullptr;
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}
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AddMpdNameSpaceInfo(&mpd);
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static const char kOnDemandProfile[] =
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"urn:mpeg:dash:profile:isoff-on-demand:2011";
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static const char kLiveProfile[] =
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"urn:mpeg:dash:profile:isoff-live:2011";
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switch (mpd_options_.dash_profile) {
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case DashProfile::kOnDemand:
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mpd.SetStringAttribute("profiles", kOnDemandProfile);
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break;
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case DashProfile::kLive:
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mpd.SetStringAttribute("profiles", kLiveProfile);
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break;
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default:
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NOTREACHED() << "Unknown DASH profile: "
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<< static_cast<int>(mpd_options_.dash_profile);
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break;
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}
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AddCommonMpdInfo(&mpd);
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switch (mpd_options_.mpd_type) {
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case MpdType::kStatic:
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AddStaticMpdInfo(&mpd);
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break;
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case MpdType::kDynamic:
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AddDynamicMpdInfo(&mpd);
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// Must be after Period element.
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AddUtcTiming(&mpd);
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break;
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default:
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NOTREACHED() << "Unknown MPD type: "
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<< static_cast<int>(mpd_options_.mpd_type);
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break;
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}
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DCHECK(doc);
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const std::string version = GetPackagerVersion();
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if (!version.empty()) {
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std::string version_string =
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base::StringPrintf("Generated with %s version %s",
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GetPackagerProjectUrl().c_str(), version.c_str());
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xml::scoped_xml_ptr<xmlNode> comment(
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xmlNewDocComment(doc.get(), BAD_CAST version_string.c_str()));
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xmlDocSetRootElement(doc.get(), comment.get());
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xmlAddSibling(comment.release(), mpd.Release());
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} else {
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xmlDocSetRootElement(doc.get(), mpd.Release());
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}
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return doc.release();
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}
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void MpdBuilder::AddCommonMpdInfo(XmlNode* mpd_node) {
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if (Positive(mpd_options_.mpd_params.min_buffer_time)) {
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mpd_node->SetStringAttribute(
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"minBufferTime",
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SecondsToXmlDuration(mpd_options_.mpd_params.min_buffer_time));
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} else {
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LOG(ERROR) << "minBufferTime value not specified.";
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// TODO(tinskip): Propagate error.
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}
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}
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void MpdBuilder::AddStaticMpdInfo(XmlNode* mpd_node) {
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DCHECK(mpd_node);
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DCHECK_EQ(MpdType::kStatic, mpd_options_.mpd_type);
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static const char kStaticMpdType[] = "static";
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mpd_node->SetStringAttribute("type", kStaticMpdType);
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mpd_node->SetStringAttribute("mediaPresentationDuration",
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SecondsToXmlDuration(GetStaticMpdDuration()));
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}
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void MpdBuilder::AddDynamicMpdInfo(XmlNode* mpd_node) {
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DCHECK(mpd_node);
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DCHECK_EQ(MpdType::kDynamic, mpd_options_.mpd_type);
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static const char kDynamicMpdType[] = "dynamic";
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mpd_node->SetStringAttribute("type", kDynamicMpdType);
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// No offset from NOW.
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mpd_node->SetStringAttribute("publishTime",
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XmlDateTimeNowWithOffset(0, clock_.get()));
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// 'availabilityStartTime' is required for dynamic profile. Calculate if
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// not already calculated.
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if (availability_start_time_.empty()) {
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double earliest_presentation_time;
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if (GetEarliestTimestamp(&earliest_presentation_time)) {
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availability_start_time_ = XmlDateTimeNowWithOffset(
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-std::ceil(earliest_presentation_time), clock_.get());
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} else {
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LOG(ERROR) << "Could not determine the earliest segment presentation "
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"time for availabilityStartTime calculation.";
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// TODO(tinskip). Propagate an error.
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}
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}
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if (!availability_start_time_.empty())
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mpd_node->SetStringAttribute("availabilityStartTime",
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availability_start_time_);
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if (Positive(mpd_options_.mpd_params.minimum_update_period)) {
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mpd_node->SetStringAttribute(
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"minimumUpdatePeriod",
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SecondsToXmlDuration(mpd_options_.mpd_params.minimum_update_period));
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} else {
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LOG(WARNING) << "The profile is dynamic but no minimumUpdatePeriod "
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"specified.";
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}
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SetIfPositive("timeShiftBufferDepth",
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mpd_options_.mpd_params.time_shift_buffer_depth, mpd_node);
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SetIfPositive("suggestedPresentationDelay",
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mpd_options_.mpd_params.suggested_presentation_delay, mpd_node);
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}
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void MpdBuilder::AddUtcTiming(XmlNode* mpd_node) {
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DCHECK(mpd_node);
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DCHECK_EQ(MpdType::kDynamic, mpd_options_.mpd_type);
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for (const MpdParams::UtcTiming& utc_timing :
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mpd_options_.mpd_params.utc_timings) {
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XmlNode utc_timing_node("UTCTiming");
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utc_timing_node.SetStringAttribute("schemeIdUri", utc_timing.scheme_id_uri);
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utc_timing_node.SetStringAttribute("value", utc_timing.value);
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mpd_node->AddChild(utc_timing_node.PassScopedPtr());
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}
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}
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float MpdBuilder::GetStaticMpdDuration() {
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DCHECK_EQ(MpdType::kStatic, mpd_options_.mpd_type);
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float total_duration = 0.0f;
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for (const auto& period : periods_) {
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total_duration += period->duration_seconds();
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}
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return total_duration;
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}
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bool MpdBuilder::GetEarliestTimestamp(double* timestamp_seconds) {
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DCHECK(timestamp_seconds);
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DCHECK(!periods_.empty());
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double timestamp = 0;
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double earliest_timestamp = -1;
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// TODO(kqyang): This is used to set availabilityStartTime. We may consider
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// set presentationTimeOffset in the Representations then we can set
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// availabilityStartTime to the time when MPD is first generated.
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// The first period should have the earliest timestamp.
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for (const auto* adaptation_set : periods_.front()->GetAdaptationSets()) {
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for (const auto* representation : adaptation_set->GetRepresentations()) {
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if (representation->GetStartAndEndTimestamps(×tamp, nullptr) &&
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(earliest_timestamp < 0 || timestamp < earliest_timestamp)) {
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earliest_timestamp = timestamp;
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}
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}
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}
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if (earliest_timestamp < 0)
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return false;
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*timestamp_seconds = earliest_timestamp;
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return true;
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}
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void MpdBuilder::UpdatePeriodDurationAndPresentationTimestamp() {
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DCHECK_EQ(MpdType::kStatic, mpd_options_.mpd_type);
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for (const auto& period : periods_) {
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std::list<Representation*> video_representations;
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std::list<Representation*> non_video_representations;
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for (const auto& adaptation_set : period->GetAdaptationSets()) {
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const auto& representations = adaptation_set->GetRepresentations();
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if (adaptation_set->IsVideo()) {
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video_representations.insert(video_representations.end(),
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representations.begin(),
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representations.end());
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} else {
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non_video_representations.insert(non_video_representations.end(),
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representations.begin(),
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representations.end());
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}
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}
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base::Optional<double> earliest_start_time;
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base::Optional<double> latest_end_time;
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// The timestamps are based on Video Representations if exist.
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const auto& representations = video_representations.size() > 0
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? video_representations
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: non_video_representations;
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for (const auto& representation : representations) {
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double start_time = 0;
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double end_time = 0;
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if (representation->GetStartAndEndTimestamps(&start_time, &end_time)) {
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earliest_start_time =
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std::min(earliest_start_time.value_or(start_time), start_time);
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latest_end_time =
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std::max(latest_end_time.value_or(end_time), end_time);
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}
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}
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if (!earliest_start_time)
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return;
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period->set_duration_seconds(*latest_end_time - *earliest_start_time);
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double presentation_time_offset = *earliest_start_time;
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for (const auto& adaptation_set : period->GetAdaptationSets()) {
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for (const auto& representation : adaptation_set->GetRepresentations()) {
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representation->SetPresentationTimeOffset(presentation_time_offset);
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}
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}
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}
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}
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void MpdBuilder::MakePathsRelativeToMpd(const std::string& mpd_path,
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MediaInfo* media_info) {
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DCHECK(media_info);
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const std::string kFileProtocol("file://");
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std::string mpd_file_path = (mpd_path.find(kFileProtocol) == 0)
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? mpd_path.substr(kFileProtocol.size())
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: mpd_path;
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if (!mpd_file_path.empty()) {
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const FilePath mpd_dir(FilePath::FromUTF8Unsafe(mpd_file_path)
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.DirName()
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.AsEndingWithSeparator());
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if (!mpd_dir.empty()) {
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if (media_info->has_media_file_name()) {
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media_info->set_media_file_name(
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MakePathRelative(media_info->media_file_name(), mpd_dir));
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}
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if (media_info->has_init_segment_name()) {
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media_info->set_init_segment_name(
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MakePathRelative(media_info->init_segment_name(), mpd_dir));
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}
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if (media_info->has_segment_template()) {
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media_info->set_segment_template(
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MakePathRelative(media_info->segment_template(), mpd_dir));
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}
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}
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}
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}
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} // namespace shaka
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