Prefer Period@duration for static MPD with >1 periods

It is easier to insert Ad Periods with Period@duration compared to
Period@start.

Change-Id: Ib52e81612562bf60b0e0513a09d9a31c42b09604

packager/app/test/testdata/bear-640x360-av-cenc-ad_cues-golden.mpd

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <!--Generated with https://github.com/google/shaka-packager version <tag>-<hash>-<test>-->
 <MPD xmlns="urn:mpeg:dash:schema:mpd:2011" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xlink="http://www.w3.org/1999/xlink" xsi:schemaLocation="urn:mpeg:dash:schema:mpd:2011 DASH-MPD.xsd" xmlns:cenc="urn:mpeg:cenc:2013" profiles="urn:mpeg:dash:profile:isoff-on-demand:2011" minBufferTime="PT2S" type="static" mediaPresentationDuration="PT2.76317S">
-  <Period id="0">
+  <Period id="0" duration="PT2.06873S">
     <AdaptationSet id="0" contentType="video" width="640" height="360" frameRate="30000/1001" subsegmentAlignment="true" par="16:9">
       <ContentProtection value="cenc" schemeIdUri="urn:mpeg:dash:mp4protection:2011" cenc:default_KID="31323334-3536-3738-3930-313233343536"/>
       <ContentProtection schemeIdUri="urn:uuid:1077efec-c0b2-4d02-ace3-3c1e52e2fb4b">
@@ -28,7 +28,7 @@
       </Representation>
     </AdaptationSet>
   </Period>
-  <Period id="1" start="PT2.06873S">
+  <Period id="1" duration="PT0.694441S">
     <AdaptationSet id="0" contentType="video" width="640" height="360" frameRate="30000/1001" subsegmentAlignment="true" par="16:9">
       <ContentProtection value="cenc" schemeIdUri="urn:mpeg:dash:mp4protection:2011" cenc:default_KID="31323334-3536-3738-3930-313233343536"/>
       <ContentProtection schemeIdUri="urn:uuid:1077efec-c0b2-4d02-ace3-3c1e52e2fb4b">

packager/app/test/testdata/bear-640x360-av-live-static-ad_cues-golden.mpd

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <!--Generated with https://github.com/google/shaka-packager version <tag>-<hash>-<test>-->
 <MPD xmlns="urn:mpeg:dash:schema:mpd:2011" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xlink="http://www.w3.org/1999/xlink" xsi:schemaLocation="urn:mpeg:dash:schema:mpd:2011 DASH-MPD.xsd" xmlns:cenc="urn:mpeg:cenc:2013" profiles="urn:mpeg:dash:profile:isoff-live:2011" minBufferTime="PT2S" type="static" mediaPresentationDuration="PT2.76317S">
-  <Period id="0">
+  <Period id="0" duration="PT2.06873S">
     <AdaptationSet id="0" contentType="video" width="640" height="360" frameRate="30000/1001" segmentAlignment="true" par="16:9">
       <Representation id="0" bandwidth="875099" codecs="avc1.64001e" mimeType="video/mp4" sar="1:1">
         <SegmentTemplate timescale="30000" initialization="output_video-init.mp4" media="output_video-$Number$.m4s" startNumber="1">
@@ -22,7 +22,7 @@
       </Representation>
     </AdaptationSet>
   </Period>
-  <Period id="1" start="PT2.06873S">
+  <Period id="1" duration="PT0.694444S">
     <AdaptationSet id="1" contentType="audio" segmentAlignment="true">
       <Representation id="1" bandwidth="108486" codecs="mp4a.40.2" mimeType="audio/mp4" audioSamplingRate="44100">
         <AudioChannelConfiguration schemeIdUri="urn:mpeg:dash:23003:3:audio_channel_configuration:2011" value="2"/>

packager/mpd/base/mpd_builder.cc

@@ -6,6 +6,8 @@
 
 #include "packager/mpd/base/mpd_builder.h"
 
+#include <algorithm>
+
 #include "packager/base/files/file_path.h"
 #include "packager/base/logging.h"
 #include "packager/base/strings/string_number_conversions.h"
@@ -170,6 +172,21 @@ xmlDocPtr MpdBuilder::GenerateMpd() {
       return nullptr;
   }
 
+  // Prefer Period@duration to Period@start for static MPD with more than one
+  // periods.
+  if (mpd_options_.mpd_type == MpdType::kStatic && periods_.size() > 1) {
+    // The duration of every period is determined by its start_time and next
+    // period start_time. The code below traverses |periods_| backwards.
+    double next_period_start_time = GetStaticMpdDuration();
+    std::for_each(
+        periods_.rbegin(), periods_.rend(),
+        [&next_period_start_time](const std::unique_ptr<Period>& period) {
+          period->set_duration_seconds(next_period_start_time -
+                                       period->start_time_in_seconds());
+          next_period_start_time = period->start_time_in_seconds();
+        });
+  }
+
   for (const auto& period : periods_) {
     xml::scoped_xml_ptr<xmlNode> period_node(period->GetXml());
     if (!period_node || !mpd.AddChild(std::move(period_node)))
@@ -242,9 +259,8 @@ void MpdBuilder::AddStaticMpdInfo(XmlNode* mpd_node) {
 
   static const char kStaticMpdType[] = "static";
   mpd_node->SetStringAttribute("type", kStaticMpdType);
-  mpd_node->SetStringAttribute(
+  mpd_node->SetStringAttribute("mediaPresentationDuration",
-      "mediaPresentationDuration",
+                               SecondsToXmlDuration(GetStaticMpdDuration()));
-      SecondsToXmlDuration(GetStaticMpdDuration(mpd_node)));
 }
 
 void MpdBuilder::AddDynamicMpdInfo(XmlNode* mpd_node) {
@@ -290,8 +306,7 @@ void MpdBuilder::AddDynamicMpdInfo(XmlNode* mpd_node) {
                 mpd_options_.mpd_params.suggested_presentation_delay, mpd_node);
 }
 
-float MpdBuilder::GetStaticMpdDuration(XmlNode* mpd_node) {
+float MpdBuilder::GetStaticMpdDuration() {
-  DCHECK(mpd_node);
   DCHECK_EQ(MpdType::kStatic, mpd_options_.mpd_type);
 
   if (periods_.empty()) {

packager/mpd/base/mpd_builder.h

@@ -100,7 +100,7 @@ class MpdBuilder {
   // Same as AddStaticMpdInfo() but for 'dynamic' MPDs.
   void AddDynamicMpdInfo(xml::XmlNode* mpd_node);
 
-  float GetStaticMpdDuration(xml::XmlNode* mpd_node);
+  float GetStaticMpdDuration();
 
   // Set MPD attributes for dynamic profile MPD. Uses non-zero |mpd_options_| as
   // well as various calculations to set attributes for the MPD.

packager/mpd/base/mpd_builder_unittest.cc

@@ -4,6 +4,7 @@
 // license that can be found in the LICENSE file or at
 // https://developers.google.com/open-source/licenses/bsd
 
+#include <gmock/gmock.h>
 #include <gtest/gtest.h>
 
 #include "packager/mpd/base/adaptation_set.h"
@@ -12,6 +13,8 @@
 #include "packager/mpd/test/mpd_builder_test_helper.h"
 #include "packager/version/version.h"
 
+using ::testing::HasSubstr;
+
 namespace shaka {
 
 namespace {
@@ -150,7 +153,7 @@ TEST_F(OnDemandMpdBuilderTest, MediaInfoMissingBandwidth) {
   ASSERT_FALSE(mpd_.ToString(&mpd_doc));
 }
 
-TEST_F(LiveMpdBuilderTest, MultiplePeriodTest) {
+TEST_F(OnDemandMpdBuilderTest, MultiplePeriodTest) {
   const double kPeriodStartTimeSeconds = 1.0;
   Period* period = mpd_.GetOrCreatePeriod(kPeriodStartTimeSeconds);
   ASSERT_TRUE(period);
@@ -170,6 +173,40 @@ TEST_F(LiveMpdBuilderTest, MultiplePeriodTest) {
   ASSERT_EQ(kPeriodStartTimeSeconds3, period3->start_time_in_seconds());
 }
 
+TEST_F(OnDemandMpdBuilderTest, MultiplePeriodCheckXmlTest) {
+  const double kPeriodStartTimeSeconds = 0.0;
+  const double kPeriodStartTimeSeconds2 = 3.1;
+  const double kPeriodStartTimeSeconds3 = 8.0;
+  mpd_.GetOrCreatePeriod(kPeriodStartTimeSeconds);
+  mpd_.GetOrCreatePeriod(kPeriodStartTimeSeconds2);
+  mpd_.GetOrCreatePeriod(kPeriodStartTimeSeconds3);
+
+  std::string mpd_doc;
+  ASSERT_TRUE(mpd_.ToString(&mpd_doc));
+  EXPECT_THAT(mpd_doc,
+              HasSubstr("  <Period id=\"0\" duration=\"PT3.1S\"/>\n"
+                        "  <Period id=\"1\" duration=\"PT4.9S\"/>\n"
+                        // There are no Representations so MPD duration is 0,
+                        // which results in a negative duration for the last
+                        // period. This would not happen in practice.
+                        "  <Period id=\"2\" duration=\"PT-8S\"/>\n"));
+}
+
+TEST_F(LiveMpdBuilderTest, MultiplePeriodCheckXmlTest) {
+  const double kPeriodStartTimeSeconds = 0.0;
+  const double kPeriodStartTimeSeconds2 = 3.1;
+  const double kPeriodStartTimeSeconds3 = 8.0;
+  mpd_.GetOrCreatePeriod(kPeriodStartTimeSeconds);
+  mpd_.GetOrCreatePeriod(kPeriodStartTimeSeconds2);
+  mpd_.GetOrCreatePeriod(kPeriodStartTimeSeconds3);
+
+  std::string mpd_doc;
+  ASSERT_TRUE(mpd_.ToString(&mpd_doc));
+  EXPECT_THAT(mpd_doc, HasSubstr("  <Period id=\"0\" start=\"PT0S\"/>\n"
+                                 "  <Period id=\"1\" start=\"PT3.1S\"/>\n"
+                                 "  <Period id=\"2\" start=\"PT8S\"/>\n"));
+}
+
 // Check whether the attributes are set correctly for dynamic <MPD> element.
 // This test must use ASSERT_EQ for comparison because XmlEqual() cannot
 // handle namespaces correctly yet.

packager/mpd/base/period.cc

@@ -94,7 +94,7 @@ AdaptationSet* Period::GetOrCreateAdaptationSet(
   return adaptation_set_ptr;
 }
 
-xml::scoped_xml_ptr<xmlNode> Period::GetXml() {
+xml::scoped_xml_ptr<xmlNode> Period::GetXml() const {
   xml::XmlNode period("Period");
 
   // Required for 'dynamic' MPDs.
@@ -106,8 +106,11 @@ xml::scoped_xml_ptr<xmlNode> Period::GetXml() {
       return nullptr;
   }
 
-  if (mpd_options_.mpd_type == MpdType::kDynamic ||
+  if (duration_seconds_ != 0) {
-      start_time_in_seconds_ != 0) {
+    period.SetStringAttribute("duration",
+                              SecondsToXmlDuration(duration_seconds_));
+  } else if (mpd_options_.mpd_type == MpdType::kDynamic ||
+             start_time_in_seconds_ != 0) {
     period.SetStringAttribute("start",
                               SecondsToXmlDuration(start_time_in_seconds_));
   }

packager/mpd/base/period.h

@@ -48,7 +48,7 @@ class Period {
   /// Generates <Period> xml element with its child AdaptationSet elements.
   /// @return On success returns a non-NULL scoped_xml_ptr. Otherwise returns a
   ///         NULL scoped_xml_ptr.
-  xml::scoped_xml_ptr<xmlNode> GetXml();
+  xml::scoped_xml_ptr<xmlNode> GetXml() const;
 
   /// @return The list of AdaptationSets in this Period.
   const std::list<AdaptationSet*> GetAdaptationSets() const;
@@ -56,6 +56,11 @@ class Period {
   /// @return The start time of this Period.
   double start_time_in_seconds() const { return start_time_in_seconds_; }
 
+  /// Set period duration.
+  void set_duration_seconds(double duration_seconds) {
+    duration_seconds_ = duration_seconds;
+  }
+
  protected:
   /// @param period_id is an ID number for this Period.
   /// @param start_time_in_seconds is the start time for this Period.
@@ -102,6 +107,7 @@ class Period {
 
   const uint32_t id_;
   const double start_time_in_seconds_;
+  double duration_seconds_ = 0;
   const MpdOptions& mpd_options_;
   base::AtomicSequenceNumber* const adaptation_set_counter_;
   base::AtomicSequenceNumber* const representation_counter_;

packager/mpd/base/period_unittest.cc

@@ -177,6 +177,38 @@ TEST_P(PeriodTest, DynamicMpdGetXml) {
   EXPECT_THAT(testable_period_.GetXml().get(), XmlNodeEqual(kExpectedXml));
 }
 
+TEST_P(PeriodTest, SetDurationAndGetXml) {
+  const char kVideoMediaInfo[] =
+      "video_info {\n"
+      "  codec: 'avc1'\n"
+      "  width: 1280\n"
+      "  height: 720\n"
+      "  time_scale: 10\n"
+      "  frame_duration: 10\n"
+      "  pixel_width: 1\n"
+      "  pixel_height: 1\n"
+      "}\n"
+      "container_type: 1\n";
+
+  EXPECT_CALL(testable_period_, NewAdaptationSet(_, _, _, _))
+      .WillOnce(Return(ByMove(std::move(default_adaptation_set_))));
+
+  ASSERT_EQ(default_adaptation_set_ptr_,
+            testable_period_.GetOrCreateAdaptationSet(
+                ConvertToMediaInfo(kVideoMediaInfo),
+                content_protection_in_adaptation_set_));
+
+  testable_period_.set_duration_seconds(100.234);
+
+  const char kExpectedXml[] =
+      "<Period id=\"9\" duration=\"PT100.234S\">"
+      // ContentType and Representation elements are populated after
+      // Representation::Init() is called.
+      "  <AdaptationSet id=\"0\" contentType=\"\"/>"
+      "</Period>";
+  EXPECT_THAT(testable_period_.GetXml().get(), XmlNodeEqual(kExpectedXml));
+}
+
 // Verify ForceSetSegmentAlignment is called.
 TEST_P(PeriodTest, Text) {
   const char kTextMediaInfo[] =

packager/mpd/base/representation.cc

@@ -315,7 +315,7 @@ float Representation::GetDurationSeconds() const {
   return media_info_.media_duration_seconds();
 }
 
-bool Representation::HasRequiredMediaInfoFields() {
+bool Representation::HasRequiredMediaInfoFields() const {
   if (HasVODOnlyFields(media_info_) && HasLiveOnlyFields(media_info_)) {
     LOG(ERROR) << "MediaInfo cannot have both VOD and Live fields.";
     return false;

packager/mpd/base/representation.h

@@ -172,7 +172,7 @@ class Representation {
 
   // Returns true if |media_info_| has required fields to generate a valid
   // Representation. Otherwise returns false.
-  bool HasRequiredMediaInfoFields();
+  bool HasRequiredMediaInfoFields() const;
 
   // Return false if the segment should be considered a new segment. True if the
   // segment is contiguous.