diff --git a/packager/hls/base/simple_hls_notifier.cc b/packager/hls/base/simple_hls_notifier.cc
index c9b36ecb2e..03e63b0cd3 100644
--- a/packager/hls/base/simple_hls_notifier.cc
+++ b/packager/hls/base/simple_hls_notifier.cc
@@ -146,7 +146,6 @@ bool SimpleHlsNotifier::NotifyNewStream(const MediaInfo& media_info,
                                         const std::string& group_id,
                                         uint32_t* stream_id) {
   DCHECK(stream_id);
-  *stream_id = sequence_number_.GetNext();
 
   MediaPlaylist::MediaPlaylistType type;
   switch (profile()) {
@@ -171,6 +170,7 @@ bool SimpleHlsNotifier::NotifyNewStream(const MediaInfo& media_info,
     return false;
   }
 
+  *stream_id = sequence_number_.GetNext();
   base::AutoLock auto_lock(lock_);
   master_playlist_->AddMediaPlaylist(media_playlist.get());
   media_playlist_map_.insert(
diff --git a/packager/media/event/hls_notify_muxer_listener.cc b/packager/media/event/hls_notify_muxer_listener.cc
index 96007b5d4d..fcd17bb0ff 100644
--- a/packager/media/event/hls_notify_muxer_listener.cc
+++ b/packager/media/event/hls_notify_muxer_listener.cc
@@ -36,6 +36,12 @@ void HlsNotifyMuxerListener::OnEncryptionInfoReady(
     const std::vector<uint8_t>& key_id,
     const std::vector<uint8_t>& iv,
     const std::vector<ProtectionSystemSpecificInfo>& key_system_infos) {
+  if (!media_started_) {
+    next_key_id_ = key_id;
+    next_iv_ = iv;
+    next_key_system_infos_ = key_system_infos;
+    return;
+  }
   for (const ProtectionSystemSpecificInfo& info : key_system_infos) {
     const bool result = hls_notifier_->NotifyEncryptionUpdate(
         stream_id_, key_id, info.system_id(), iv, info.pssh_data());
@@ -43,6 +49,28 @@ void HlsNotifyMuxerListener::OnEncryptionInfoReady(
   }
 }
 
+void HlsNotifyMuxerListener::OnEncryptionStart() {
+  if (!media_started_) {
+    DLOG(WARNING) << "Media not started, cannot notify encryption start.";
+    return;
+  }
+  if (next_key_id_.empty()) {
+    DCHECK(next_iv_.empty());
+    DCHECK(next_key_system_infos_.empty());
+    return;
+  }
+
+  for (const ProtectionSystemSpecificInfo& info : next_key_system_infos_) {
+    const bool result = hls_notifier_->NotifyEncryptionUpdate(
+        stream_id_, next_key_id_, info.system_id(), next_iv_,
+        info.pssh_data());
+    LOG_IF(WARNING, !result) << "Failed to add encryption info";
+  }
+  next_key_id_.clear();
+  next_iv_.clear();
+  next_key_system_infos_.clear();
+}
+
 void HlsNotifyMuxerListener::OnMediaStart(const MuxerOptions& muxer_options,
                                           const StreamInfo& stream_info,
                                           uint32_t time_scale,
@@ -56,7 +84,12 @@ void HlsNotifyMuxerListener::OnMediaStart(const MuxerOptions& muxer_options,
   const bool result = hls_notifier_->NotifyNewStream(
       media_info, playlist_name_, ext_x_media_name_, ext_x_media_group_id_,
       &stream_id_);
-  LOG_IF(WARNING, !result) << "Failed to notify new stream.";
+  if (!result) {
+    LOG(WARNING) << "Failed to notify new stream.";
+    return;
+  }
+
+  media_started_ = true;
 }
 
 void HlsNotifyMuxerListener::OnSampleDurationReady(uint32_t sample_duration) {}
diff --git a/packager/media/event/hls_notify_muxer_listener.h b/packager/media/event/hls_notify_muxer_listener.h
index 5390295f14..b402ea144f 100644
--- a/packager/media/event/hls_notify_muxer_listener.h
+++ b/packager/media/event/hls_notify_muxer_listener.h
@@ -45,6 +45,7 @@ class HlsNotifyMuxerListener : public MuxerListener {
                              const std::vector<uint8_t>& iv,
                              const std::vector<ProtectionSystemSpecificInfo>&
                                  key_system_info) override;
+  void OnEncryptionStart() override;
   void OnMediaStart(const MuxerOptions& muxer_options,
                     const StreamInfo& stream_info,
                     uint32_t time_scale,
@@ -71,6 +72,12 @@ class HlsNotifyMuxerListener : public MuxerListener {
   hls::HlsNotifier* const hls_notifier_;
   uint32_t stream_id_ = 0;
 
+  bool media_started_ = false;
+  // Cached encryption info before OnMediaStart() is called.
+  std::vector<uint8_t> next_key_id_;
+  std::vector<uint8_t> next_iv_;
+  std::vector<ProtectionSystemSpecificInfo> next_key_system_infos_;
+
   DISALLOW_COPY_AND_ASSIGN(HlsNotifyMuxerListener);
 };
 
diff --git a/packager/media/event/hls_notify_muxer_listener_unittest.cc b/packager/media/event/hls_notify_muxer_listener_unittest.cc
index 9b09543e32..be8739db87 100644
--- a/packager/media/event/hls_notify_muxer_listener_unittest.cc
+++ b/packager/media/event/hls_notify_muxer_listener_unittest.cc
@@ -83,7 +83,126 @@ class HlsNotifyMuxerListenerTest : public ::testing::Test {
   HlsNotifyMuxerListener listener_;
 };
 
+// Verify that NotifyEncryptionUpdate() is not called before OnMediaStart() is
+// called.
+TEST_F(HlsNotifyMuxerListenerTest, OnEncryptionInfoReadyBeforeMediaStart) {
+  ProtectionSystemSpecificInfo info;
+  std::vector<uint8_t> system_id(kAnySystemId,
+                                 kAnySystemId + arraysize(kAnySystemId));
+  info.set_system_id(system_id.data(), system_id.size());
+  std::vector<uint8_t> pssh_data(kAnyData, kAnyData + arraysize(kAnyData));
+  info.set_pssh_data(pssh_data);
+
+  std::vector<uint8_t> key_id(16, 0x05);
+  std::vector<ProtectionSystemSpecificInfo> key_system_infos;
+  key_system_infos.push_back(info);
+
+  std::vector<uint8_t> iv(16, 0x54);
+
+  EXPECT_CALL(mock_notifier_, NotifyEncryptionUpdate(_, _, _, _, _)).Times(0);
+  listener_.OnEncryptionInfoReady(kInitialEncryptionInfo, FOURCC_cbcs, key_id,
+                                  iv, key_system_infos);
+}
+
+TEST_F(HlsNotifyMuxerListenerTest, OnMediaStart) {
+  VideoStreamInfoParameters video_params = GetDefaultVideoStreamInfoParams();
+  scoped_refptr<StreamInfo> video_stream_info =
+      CreateVideoStreamInfo(video_params);
+
+  EXPECT_CALL(mock_notifier_,
+              NotifyNewStream(_, StrEq(kDefaultPlaylistName),
+                              StrEq("DEFAULTNAME"), StrEq("DEFAULTGROUPID"), _))
+      .WillOnce(Return(true));
+
+  MuxerOptions muxer_options;
+  listener_.OnMediaStart(muxer_options, *video_stream_info, 90000,
+                         MuxerListener::kContainerMpeg2ts);
+}
+
+// OnEncryptionStart() should NotifyEncryptionUpdate() after
+// OnEncryptionInfoReady() and OnMediaStart().
+TEST_F(HlsNotifyMuxerListenerTest, OnEncryptionStart) {
+  ProtectionSystemSpecificInfo info;
+  std::vector<uint8_t> system_id(kAnySystemId,
+                                 kAnySystemId + arraysize(kAnySystemId));
+  info.set_system_id(system_id.data(), system_id.size());
+  std::vector<uint8_t> pssh_data(kAnyData, kAnyData + arraysize(kAnyData));
+  info.set_pssh_data(pssh_data);
+
+  std::vector<uint8_t> key_id(16, 0x05);
+  std::vector<ProtectionSystemSpecificInfo> key_system_infos;
+  key_system_infos.push_back(info);
+
+  std::vector<uint8_t> iv(16, 0x54);
+
+  EXPECT_CALL(mock_notifier_, NotifyEncryptionUpdate(_, _, _, _, _)).Times(0);
+  listener_.OnEncryptionInfoReady(kInitialEncryptionInfo, FOURCC_cbcs, key_id,
+                                  iv, key_system_infos);
+  ::testing::Mock::VerifyAndClearExpectations(&mock_notifier_);
+
+  ON_CALL(mock_notifier_, NotifyNewStream(_, _, _, _, _))
+      .WillByDefault(Return(true));
+  VideoStreamInfoParameters video_params = GetDefaultVideoStreamInfoParams();
+  scoped_refptr<StreamInfo> video_stream_info =
+      CreateVideoStreamInfo(video_params);
+  MuxerOptions muxer_options;
+
+  EXPECT_CALL(mock_notifier_, NotifyEncryptionUpdate(_, _, _, _, _)).Times(0);
+  listener_.OnMediaStart(muxer_options, *video_stream_info, 90000,
+                         MuxerListener::kContainerMpeg2ts);
+  ::testing::Mock::VerifyAndClearExpectations(&mock_notifier_);
+
+  EXPECT_CALL(mock_notifier_,
+              NotifyEncryptionUpdate(_, key_id, system_id, iv, pssh_data))
+      .WillOnce(Return(true));
+  listener_.OnEncryptionStart();
+}
+
+// NotifyEncryptionUpdate() should not be called if NotifyNewStream() fails in
+// OnMediaStart().
+TEST_F(HlsNotifyMuxerListenerTest, NoEncryptionUpdateIfNotifyNewStreamFails) {
+  ProtectionSystemSpecificInfo info;
+  std::vector<uint8_t> system_id(kAnySystemId,
+                                 kAnySystemId + arraysize(kAnySystemId));
+  info.set_system_id(system_id.data(), system_id.size());
+  std::vector<uint8_t> pssh_data(kAnyData, kAnyData + arraysize(kAnyData));
+  info.set_pssh_data(pssh_data);
+
+  std::vector<uint8_t> key_id(16, 0x05);
+  std::vector<ProtectionSystemSpecificInfo> key_system_infos;
+  key_system_infos.push_back(info);
+
+  std::vector<uint8_t> iv(16, 0x54);
+
+  EXPECT_CALL(mock_notifier_, NotifyEncryptionUpdate(_, _, _, _, _)).Times(0);
+  listener_.OnEncryptionInfoReady(kInitialEncryptionInfo, FOURCC_cbcs, key_id,
+                                  iv, key_system_infos);
+  ::testing::Mock::VerifyAndClearExpectations(&mock_notifier_);
+
+  EXPECT_CALL(mock_notifier_, NotifyNewStream(_, _, _, _, _))
+      .WillOnce(Return(false));
+  VideoStreamInfoParameters video_params = GetDefaultVideoStreamInfoParams();
+  scoped_refptr<StreamInfo> video_stream_info =
+      CreateVideoStreamInfo(video_params);
+  MuxerOptions muxer_options;
+
+  EXPECT_CALL(mock_notifier_, NotifyEncryptionUpdate(_, _, _, _, _)).Times(0);
+  listener_.OnMediaStart(muxer_options, *video_stream_info, 90000,
+                         MuxerListener::kContainerMpeg2ts);
+}
+
+// Verify that after OnMediaStart(), OnEncryptionInfoReady() calls
+// NotifyEncryptionUpdate().
 TEST_F(HlsNotifyMuxerListenerTest, OnEncryptionInfoReady) {
+  ON_CALL(mock_notifier_, NotifyNewStream(_, _, _, _, _))
+      .WillByDefault(Return(true));
+  VideoStreamInfoParameters video_params = GetDefaultVideoStreamInfoParams();
+  scoped_refptr<StreamInfo> video_stream_info =
+      CreateVideoStreamInfo(video_params);
+  MuxerOptions muxer_options;
+  listener_.OnMediaStart(muxer_options, *video_stream_info, 90000,
+                         MuxerListener::kContainerMpeg2ts);
+
   ProtectionSystemSpecificInfo info;
   std::vector<uint8_t> system_id(kAnySystemId,
                                  kAnySystemId + arraysize(kAnySystemId));
@@ -104,21 +223,6 @@ TEST_F(HlsNotifyMuxerListenerTest, OnEncryptionInfoReady) {
                                   iv, key_system_infos);
 }
 
-TEST_F(HlsNotifyMuxerListenerTest, OnMediaStart) {
-  VideoStreamInfoParameters video_params = GetDefaultVideoStreamInfoParams();
-  scoped_refptr<StreamInfo> video_stream_info =
-      CreateVideoStreamInfo(video_params);
-
-  EXPECT_CALL(mock_notifier_,
-              NotifyNewStream(_, StrEq(kDefaultPlaylistName),
-                              StrEq("DEFAULTNAME"), StrEq("DEFAULTGROUPID"), _))
-      .WillOnce(Return(true));
-
-  MuxerOptions muxer_options;
-  listener_.OnMediaStart(muxer_options, *video_stream_info, 90000,
-                         MuxerListener::kContainerMpeg2ts);
-}
-
 // Make sure it doesn't crash.
 TEST_F(HlsNotifyMuxerListenerTest, OnSampleDurationReady) {
   listener_.OnSampleDurationReady(2340);
diff --git a/packager/media/event/mock_muxer_listener.h b/packager/media/event/mock_muxer_listener.h
index c89f5f2a13..d30dab8b9d 100644
--- a/packager/media/event/mock_muxer_listener.h
+++ b/packager/media/event/mock_muxer_listener.h
@@ -30,6 +30,8 @@ class MockMuxerListener : public MuxerListener {
            const std::vector<uint8_t>& iv,
            const std::vector<ProtectionSystemSpecificInfo>& key_system_info));
 
+  MOCK_METHOD0(OnEncryptionStart, void());
+
   MOCK_METHOD4(OnMediaStart,
                void(const MuxerOptions& muxer_options,
                     const StreamInfo& stream_info,
diff --git a/packager/media/event/mpd_notify_muxer_listener.cc b/packager/media/event/mpd_notify_muxer_listener.cc
index dd14843308..fd017f8ca6 100644
--- a/packager/media/event/mpd_notify_muxer_listener.cc
+++ b/packager/media/event/mpd_notify_muxer_listener.cc
@@ -54,6 +54,8 @@ void MpdNotifyMuxerListener::OnEncryptionInfoReady(
   }
 }
 
+void MpdNotifyMuxerListener::OnEncryptionStart() {}
+
 void MpdNotifyMuxerListener::OnMediaStart(
     const MuxerOptions& muxer_options,
     const StreamInfo& stream_info,
diff --git a/packager/media/event/mpd_notify_muxer_listener.h b/packager/media/event/mpd_notify_muxer_listener.h
index fa2e81cde2..cfed22ce14 100644
--- a/packager/media/event/mpd_notify_muxer_listener.h
+++ b/packager/media/event/mpd_notify_muxer_listener.h
@@ -39,6 +39,7 @@ class MpdNotifyMuxerListener : public MuxerListener {
                              const std::vector<uint8_t>& iv,
                              const std::vector<ProtectionSystemSpecificInfo>&
                                  key_system_info) override;
+  void OnEncryptionStart() override;
   void OnMediaStart(const MuxerOptions& muxer_options,
                     const StreamInfo& stream_info,
                     uint32_t time_scale,
diff --git a/packager/media/event/muxer_listener.h b/packager/media/event/muxer_listener.h
index 87fc929912..393a9ab5f2 100644
--- a/packager/media/event/muxer_listener.h
+++ b/packager/media/event/muxer_listener.h
@@ -64,6 +64,12 @@ class MuxerListener {
       const std::vector<uint8_t>& iv,
       const std::vector<ProtectionSystemSpecificInfo>& key_system_info) = 0;
 
+  /// Called when the muxer starts encrypting the segments.
+  /// Further segments notified via OnNewSegment() are encrypted.
+  /// This may be called more than once e.g. per segment, but the semantics does
+  /// not change.
+  virtual void OnEncryptionStart() = 0;
+
   /// Called when muxing starts.
   /// For MPEG DASH Live profile, the initialization segment information is
   /// available from StreamInfo.
diff --git a/packager/media/event/vod_media_info_dump_muxer_listener.cc b/packager/media/event/vod_media_info_dump_muxer_listener.cc
index 11a6f9401b..b598df62ba 100644
--- a/packager/media/event/vod_media_info_dump_muxer_listener.cc
+++ b/packager/media/event/vod_media_info_dump_muxer_listener.cc
@@ -62,6 +62,8 @@ void VodMediaInfoDumpMuxerListener::OnMediaStart(
   }
 }
 
+void VodMediaInfoDumpMuxerListener::OnEncryptionStart() {}
+
 void VodMediaInfoDumpMuxerListener::OnSampleDurationReady(
     uint32_t sample_duration) {
   // Assume one VideoInfo.
diff --git a/packager/media/event/vod_media_info_dump_muxer_listener.h b/packager/media/event/vod_media_info_dump_muxer_listener.h
index fba8a5d027..70daa66da8 100644
--- a/packager/media/event/vod_media_info_dump_muxer_listener.h
+++ b/packager/media/event/vod_media_info_dump_muxer_listener.h
@@ -38,6 +38,7 @@ class VodMediaInfoDumpMuxerListener : public MuxerListener {
                              const std::vector<uint8_t>& iv,
                              const std::vector<ProtectionSystemSpecificInfo>&
                                  key_system_info) override;
+  void OnEncryptionStart() override;
   void OnMediaStart(const MuxerOptions& muxer_options,
                     const StreamInfo& stream_info,
                     uint32_t time_scale,
diff --git a/packager/media/formats/mp2t/ts_segmenter.cc b/packager/media/formats/mp2t/ts_segmenter.cc
index 1eb80636ec..458c2c3989 100644
--- a/packager/media/formats/mp2t/ts_segmenter.cc
+++ b/packager/media/formats/mp2t/ts_segmenter.cc
@@ -57,8 +57,18 @@ Status TsSegmenter::Initialize(const StreamInfo& stream_info,
     }
     if (!status.ok())
       return status;
+
     encryption_key_ = encryption_key.Pass();
     clear_lead_in_seconds_ = clear_lead_in_seconds;
+
+    if (listener_) {
+      // For now this only happens once, so send true.
+      const bool kIsInitialEncryptionInfo = true;
+      listener_->OnEncryptionInfoReady(
+          kIsInitialEncryptionInfo, FOURCC_cbcs, encryption_key_->key_id,
+          encryption_key_->iv, encryption_key_->key_system_info);
+    }
+
     status = NotifyEncrypted();
     if (!status.ok())
       return status;
@@ -174,13 +184,8 @@ Status TsSegmenter::Flush() {
 
 Status TsSegmenter::NotifyEncrypted() {
   if (encryption_key_ && total_duration_in_seconds_ >= clear_lead_in_seconds_) {
-    if (listener_) {
-      // For now this only happens once, so send true.
-      const bool kIsInitialEncryptionInfo = true;
-      listener_->OnEncryptionInfoReady(
-          kIsInitialEncryptionInfo, FOURCC_cbcs, encryption_key_->key_id,
-          encryption_key_->iv, encryption_key_->key_system_info);
-    }
+    if (listener_)
+      listener_->OnEncryptionStart();
 
     if (!pes_packet_generator_->SetEncryptionKey(encryption_key_.Pass()))
       return Status(error::INTERNAL_ERROR, "Failed to set encryption key.");
diff --git a/packager/media/formats/mp2t/ts_segmenter_unittest.cc b/packager/media/formats/mp2t/ts_segmenter_unittest.cc
index 77ea659560..07acf20cb9 100644
--- a/packager/media/formats/mp2t/ts_segmenter_unittest.cc
+++ b/packager/media/formats/mp2t/ts_segmenter_unittest.cc
@@ -481,6 +481,44 @@ TEST_F(TsSegmenterTest, WithEncryptionNoClearLead) {
                                  kClearLeadSeconds));
 }
 
+// Verify that the muxer listener pointer is not used without checking that it's
+// not null.
+TEST_F(TsSegmenterTest, WithEncryptionNoClearLeadNoMuxerListener) {
+  scoped_refptr<VideoStreamInfo> stream_info(new VideoStreamInfo(
+      kTrackId, kTimeScale, kDuration, kH264VideoCodec, kCodecString, kLanguage,
+      kWidth, kHeight, kPixelWidth, kPixelHeight, kTrickPlayRate,
+      kNaluLengthSize, kExtraData, arraysize(kExtraData), kIsEncrypted));
+  MuxerOptions options;
+  options.segment_duration = 10.0;
+  options.segment_template = "file$Number$.ts";
+
+  TsSegmenter segmenter(options, nullptr);
+
+  EXPECT_CALL(*mock_ts_writer_, Initialize(_)).WillOnce(Return(true));
+  EXPECT_CALL(*mock_ts_writer_, SignalEncypted());
+  EXPECT_CALL(*mock_pes_packet_generator_, Initialize(_))
+      .WillOnce(Return(true));
+
+  EXPECT_CALL(*mock_pes_packet_generator_, SetEncryptionKeyMock(_))
+      .WillOnce(Return(true));
+
+  segmenter.InjectTsWriterForTesting(mock_ts_writer_.Pass());
+  segmenter.InjectPesPacketGeneratorForTesting(
+      mock_pes_packet_generator_.Pass());
+
+  MockKeySource mock_key_source;
+  EXPECT_CALL(mock_key_source, GetKey(KeySource::TRACK_TYPE_HD, _))
+      .WillOnce(Return(Status::OK));
+
+  const uint32_t k480pPixels = 640 * 480;
+  // Set this to 0 so that Finalize will call
+  // PesPacketGenerator::SetEncryptionKey().
+  // Even tho no samples have been added.
+  const double kClearLeadSeconds = 0;
+  EXPECT_OK(segmenter.Initialize(*stream_info, &mock_key_source, k480pPixels,
+                                 kClearLeadSeconds));
+}
+
 // Verify that encryption notification is sent to objects after clear lead.
 TEST_F(TsSegmenterTest, WithEncryptionWithClearLead) {
   scoped_refptr<VideoStreamInfo> stream_info(new VideoStreamInfo(
@@ -568,13 +606,14 @@ TEST_F(TsSegmenterTest, WithEncryptionWithClearLead) {
   EXPECT_CALL(mock_key_source, GetKey(KeySource::TRACK_TYPE_HD, _))
       .WillOnce(Return(Status::OK));
 
+  EXPECT_CALL(mock_listener, OnEncryptionInfoReady(_, _, _, _, _));
   EXPECT_OK(segmenter.Initialize(*stream_info, &mock_key_source, 0,
                                  kClearLeadSeconds));
   EXPECT_OK(segmenter.AddSample(sample1));
 
   // These should be called AFTER the first AddSample(), before the second
   // segment.
-  EXPECT_CALL(mock_listener, OnEncryptionInfoReady(_, _, _, _, _));
+  EXPECT_CALL(mock_listener, OnEncryptionStart());
   EXPECT_CALL(*mock_pes_packet_generator_raw, SetEncryptionKeyMock(_))
       .WillOnce(Return(true));
   EXPECT_CALL(*mock_ts_writer_raw, SignalEncypted());
diff --git a/packager/media/formats/mp4/encrypting_fragmenter.cc b/packager/media/formats/mp4/encrypting_fragmenter.cc
index 46fd66fd30..610d511316 100644
--- a/packager/media/formats/mp4/encrypting_fragmenter.cc
+++ b/packager/media/formats/mp4/encrypting_fragmenter.cc
@@ -66,7 +66,8 @@ EncryptingFragmenter::EncryptingFragmenter(
     int64_t clear_time,
     FourCC protection_scheme,
     uint8_t crypt_byte_block,
-    uint8_t skip_byte_block)
+    uint8_t skip_byte_block,
+    MuxerListener* listener)
     : Fragmenter(info, traf),
       info_(info),
       encryption_key_(encryption_key.Pass()),
@@ -75,7 +76,8 @@ EncryptingFragmenter::EncryptingFragmenter(
       clear_time_(clear_time),
       protection_scheme_(protection_scheme),
       crypt_byte_block_(crypt_byte_block),
-      skip_byte_block_(skip_byte_block) {
+      skip_byte_block_(skip_byte_block),
+      listener_(listener) {
   DCHECK(encryption_key_);
   switch (video_codec_) {
     case kCodecVP8:
@@ -143,6 +145,9 @@ Status EncryptingFragmenter::InitializeFragment(int64_t first_sample_dts) {
     traf()->header.flags |=
         TrackFragmentHeader::kSampleDescriptionIndexPresentMask;
     traf()->header.sample_description_index = kClearSampleDescriptionIndex;
+  } else {
+    if (listener_)
+      listener_->OnEncryptionStart();
   }
   return PrepareFragmentForEncryption(enable_encryption);
 }
diff --git a/packager/media/formats/mp4/encrypting_fragmenter.h b/packager/media/formats/mp4/encrypting_fragmenter.h
index 01d64da76f..bd666779f3 100644
--- a/packager/media/formats/mp4/encrypting_fragmenter.h
+++ b/packager/media/formats/mp4/encrypting_fragmenter.h
@@ -12,6 +12,7 @@
 #include "packager/media/base/fourccs.h"
 #include "packager/media/codecs/video_slice_header_parser.h"
 #include "packager/media/codecs/vpx_parser.h"
+#include "packager/media/event/muxer_listener.h"
 #include "packager/media/formats/mp4/fragmenter.h"
 
 namespace shaka {
@@ -43,7 +44,8 @@ class EncryptingFragmenter : public Fragmenter {
                        int64_t clear_time,
                        FourCC protection_scheme,
                        uint8_t crypt_byte_block,
-                       uint8_t skip_byte_block);
+                       uint8_t skip_byte_block,
+                       MuxerListener* listener);
 
   ~EncryptingFragmenter() override;
 
@@ -95,6 +97,7 @@ class EncryptingFragmenter : public Fragmenter {
   const FourCC protection_scheme_;
   const uint8_t crypt_byte_block_;
   const uint8_t skip_byte_block_;
+  MuxerListener* listener_;
 
   scoped_ptr<VPxParser> vpx_parser_;
   scoped_ptr<VideoSliceHeaderParser> header_parser_;
diff --git a/packager/media/formats/mp4/key_rotation_fragmenter.cc b/packager/media/formats/mp4/key_rotation_fragmenter.cc
index f8eea8be8a..c5be9d778a 100644
--- a/packager/media/formats/mp4/key_rotation_fragmenter.cc
+++ b/packager/media/formats/mp4/key_rotation_fragmenter.cc
@@ -34,7 +34,8 @@ KeyRotationFragmenter::KeyRotationFragmenter(MovieFragment* moof,
                            clear_time,
                            protection_scheme,
                            crypt_byte_block,
-                           skip_byte_block),
+                           skip_byte_block,
+                           muxer_listener),
       moof_(moof),
       encryption_key_source_(encryption_key_source),
       track_type_(track_type),
diff --git a/packager/media/formats/mp4/segmenter.cc b/packager/media/formats/mp4/segmenter.cc
index 5b35794e00..a487be4919 100644
--- a/packager/media/formats/mp4/segmenter.cc
+++ b/packager/media/formats/mp4/segmenter.cc
@@ -259,7 +259,8 @@ Status Segmenter::Initialize(const std::vector<MediaStream*>& streams,
     fragmenters_[i] = new EncryptingFragmenter(
         streams[i]->info(), &moof_->tracks[i], encryption_key.Pass(),
         clear_lead_in_seconds * streams[i]->info()->time_scale(),
-        protection_scheme, pattern.crypt_byte_block, pattern.skip_byte_block);
+        protection_scheme, pattern.crypt_byte_block, pattern.skip_byte_block,
+        muxer_listener_);
   }
 
   // Choose the first stream if there is no VIDEO.
diff --git a/packager/media/formats/webm/segmenter.cc b/packager/media/formats/webm/segmenter.cc
index d4c40114b9..f40771953a 100644
--- a/packager/media/formats/webm/segmenter.cc
+++ b/packager/media/formats/webm/segmenter.cc
@@ -166,6 +166,8 @@ Status Segmenter::AddSample(scoped_refptr<MediaSample> sample) {
       LOG(ERROR) << "Error encrypting frame.";
       return status;
     }
+    if (encrypt_frame && muxer_listener_)
+      muxer_listener_->OnEncryptionStart();
   }