diff --git a/packager/media/base/fixed_key_source.cc b/packager/media/base/fixed_key_source.cc
index bae4c5de22..2688d01294 100644
--- a/packager/media/base/fixed_key_source.cc
+++ b/packager/media/base/fixed_key_source.cc
@@ -21,7 +21,8 @@ Status FixedKeySource::FetchKeys(EmeInitDataType init_data_type,
   return Status::OK;
 }
 
-Status FixedKeySource::GetKey(TrackType track_type, EncryptionKey* key) {
+Status FixedKeySource::GetKey(const std::string& stream_label,
+                              EncryptionKey* key) {
   DCHECK(key);
   DCHECK(encryption_key_);
   *key = *encryption_key_;
@@ -43,7 +44,7 @@ Status FixedKeySource::GetKey(const std::vector<uint8_t>& key_id,
 }
 
 Status FixedKeySource::GetCryptoPeriodKey(uint32_t crypto_period_index,
-                                          TrackType track_type,
+                                          const std::string& stream_label,
                                           EncryptionKey* key) {
   // Create a copy of the key.
   *key = *encryption_key_;
diff --git a/packager/media/base/fixed_key_source.h b/packager/media/base/fixed_key_source.h
index df07d946de..0a8ed06b76 100644
--- a/packager/media/base/fixed_key_source.h
+++ b/packager/media/base/fixed_key_source.h
@@ -32,11 +32,11 @@ class FixedKeySource : public KeySource {
   /// @{
   Status FetchKeys(EmeInitDataType init_data_type,
                    const std::vector<uint8_t>& init_data) override;
-  Status GetKey(TrackType track_type, EncryptionKey* key) override;
+  Status GetKey(const std::string& stream_label, EncryptionKey* key) override;
   Status GetKey(const std::vector<uint8_t>& key_id,
                 EncryptionKey* key) override;
   Status GetCryptoPeriodKey(uint32_t crypto_period_index,
-                            TrackType track_type,
+                            const std::string& stream_label,
                             EncryptionKey* key) override;
   /// @}
 
diff --git a/packager/media/base/fixed_key_source_unittest.cc b/packager/media/base/fixed_key_source_unittest.cc
index 34f61bdf80..9f5aa4b8cb 100644
--- a/packager/media/base/fixed_key_source_unittest.cc
+++ b/packager/media/base/fixed_key_source_unittest.cc
@@ -53,7 +53,7 @@ TEST(FixedKeySourceTest, CreateFromHexStrings_Succes) {
   ASSERT_NE(nullptr, key_source);
 
   EncryptionKey key;
-  ASSERT_OK(key_source->GetKey(KeySource::TRACK_TYPE_SD, &key));
+  ASSERT_OK(key_source->GetKey("SomeStreamLabel", &key));
 
   EXPECT_HEX_EQ(kKeyIdHex, key.key_id);
   EXPECT_HEX_EQ(kKeyHex, key.key);
@@ -70,7 +70,7 @@ TEST(FixedKeySourceTest, CreateFromHexStrings_EmptyPssh) {
   ASSERT_NE(nullptr, key_source);
 
   EncryptionKey key;
-  ASSERT_OK(key_source->GetKey(KeySource::TRACK_TYPE_SD, &key));
+  ASSERT_OK(key_source->GetKey("SomeStreamLabel", &key));
 
   EXPECT_HEX_EQ(kKeyIdHex, key.key_id);
   EXPECT_HEX_EQ(kKeyHex, key.key);
diff --git a/packager/media/base/key_source.cc b/packager/media/base/key_source.cc
index 240c92538b..b652396e85 100644
--- a/packager/media/base/key_source.cc
+++ b/packager/media/base/key_source.cc
@@ -12,47 +12,12 @@ namespace shaka {
 namespace media {
 
 EncryptionKey::EncryptionKey() {}
+
 EncryptionKey::~EncryptionKey() {}
 
-KeySource::~KeySource() {}
-
-KeySource::TrackType KeySource::GetTrackTypeFromString(
-    const std::string& track_type_string) {
-  if (track_type_string == "SD")
-    return TRACK_TYPE_SD;
-  if (track_type_string == "HD")
-    return TRACK_TYPE_HD;
-  if (track_type_string == "UHD1")
-    return TRACK_TYPE_UHD1;
-  if (track_type_string == "UHD2")
-    return TRACK_TYPE_UHD2;
-  if (track_type_string == "AUDIO")
-    return TRACK_TYPE_AUDIO;
-  if (track_type_string == "UNSPECIFIED")
-    return TRACK_TYPE_UNSPECIFIED;
-  LOG(WARNING) << "Unexpected track type: " << track_type_string;
-  return TRACK_TYPE_UNKNOWN;
-}
-
-std::string KeySource::TrackTypeToString(TrackType track_type) {
-  switch (track_type) {
-    case TRACK_TYPE_SD:
-      return "SD";
-    case TRACK_TYPE_HD:
-      return "HD";
-    case TRACK_TYPE_UHD1:
-      return "UHD1";
-    case TRACK_TYPE_UHD2:
-      return "UHD2";
-    case TRACK_TYPE_AUDIO:
-      return "AUDIO";
-    default:
-      NOTIMPLEMENTED() << "Unknown track type: " << track_type;
-      return "UNKNOWN";
-  }
-}
-
 KeySource::KeySource() {}
 
+KeySource::~KeySource() {}
+
 }  // namespace media
 }  // namespace shaka
diff --git a/packager/media/base/key_source.h b/packager/media/base/key_source.h
index 2883e6cb82..59932a9a9b 100644
--- a/packager/media/base/key_source.h
+++ b/packager/media/base/key_source.h
@@ -44,17 +44,6 @@ struct EncryptionKey {
 /// KeySource is responsible for encryption key acquisition.
 class KeySource {
  public:
-  enum TrackType {
-    TRACK_TYPE_UNKNOWN = 0,
-    TRACK_TYPE_SD = 1,
-    TRACK_TYPE_HD = 2,
-    TRACK_TYPE_UHD1 = 3,
-    TRACK_TYPE_UHD2 = 4,
-    TRACK_TYPE_AUDIO = 5,
-    TRACK_TYPE_UNSPECIFIED = 6,
-    NUM_VALID_TRACK_TYPES = 6
-  };
-
   KeySource();
   virtual ~KeySource();
 
@@ -65,12 +54,13 @@ class KeySource {
   virtual Status FetchKeys(EmeInitDataType init_data_type,
                            const std::vector<uint8_t>& init_data) = 0;
 
-  /// Get encryption key of the specified track type.
-  /// @param track_type is the type of track for which retrieving the key.
+  /// Get encryption key of the specified stream label.
+  /// @param stream_label is the label of stream for which retrieving the key.
   /// @param key is a pointer to the EncryptionKey which will hold the retrieved
   ///        key. Owner retains ownership, and may not be NULL.
   /// @return OK on success, an error status otherwise.
-  virtual Status GetKey(TrackType track_type, EncryptionKey* key) = 0;
+  virtual Status GetKey(const std::string& stream_label,
+                        EncryptionKey* key) = 0;
 
   /// Get the encryption key specified by the CENC key ID.
   /// @param key_id is the unique identifier for the key being retreived.
@@ -83,20 +73,14 @@ class KeySource {
   /// Get encryption key of the specified track type at the specified index.
   /// @param crypto_period_index is the sequence number of the key rotation
   ///        period for which the key is being retrieved.
-  /// @param track_type is the type of track for which retrieving the key.
+  /// @param stream_label is the label of stream for which retrieving the key.
   /// @param key is a pointer to the EncryptionKey which will hold the retrieved
   ///        key. Owner retains ownership, and may not be NULL.
   /// @return OK on success, an error status otherwise.
   virtual Status GetCryptoPeriodKey(uint32_t crypto_period_index,
-                                    TrackType track_type,
+                                    const std::string& stream_label,
                                     EncryptionKey* key) = 0;
 
-  /// Convert string representation of track type to enum representation.
-  static TrackType GetTrackTypeFromString(const std::string& track_type_string);
-
-  /// Convert TrackType to string.
-  static std::string TrackTypeToString(TrackType track_type);
-
  private:
   DISALLOW_COPY_AND_ASSIGN(KeySource);
 };
diff --git a/packager/media/base/playready_key_source.cc b/packager/media/base/playready_key_source.cc
index ed6a6d52cd..bbca55c362 100644
--- a/packager/media/base/playready_key_source.cc
+++ b/packager/media/base/playready_key_source.cc
@@ -316,9 +316,10 @@ Status PlayReadyKeySource::FetchKeys(EmeInitDataType init_data_type,
   return Status::OK;
 }
 
-Status PlayReadyKeySource::GetKey(TrackType track_type, EncryptionKey* key) {
+Status PlayReadyKeySource::GetKey(const std::string& stream_label,
+                                  EncryptionKey* key) {
   // TODO(robinconnell): Currently all tracks are encrypted using the same
-  // key_id and key.  Add the ability to encrypt each track_type using a
+  // key_id and key.  Add the ability to encrypt each stream_label using a
   // different key_id and key.
   DCHECK(key);
   DCHECK(encryption_key_);
@@ -337,7 +338,7 @@ Status PlayReadyKeySource::GetKey(const std::vector<uint8_t>& key_id,
 }
 
 Status PlayReadyKeySource::GetCryptoPeriodKey(uint32_t crypto_period_index,
-                                              TrackType track_type,
+                                              const std::string& stream_label,
                                               EncryptionKey* key) {
   // TODO(robinconnell): Implement key rotation.
   *key = *encryption_key_;
diff --git a/packager/media/base/playready_key_source.h b/packager/media/base/playready_key_source.h
index 290e18281e..90b9fb5f87 100644
--- a/packager/media/base/playready_key_source.h
+++ b/packager/media/base/playready_key_source.h
@@ -42,11 +42,11 @@ class PlayReadyKeySource : public KeySource {
   /// @{
   Status FetchKeys(EmeInitDataType init_data_type,
                    const std::vector<uint8_t>& init_data) override;
-  Status GetKey(TrackType track_type, EncryptionKey* key) override;
+  Status GetKey(const std::string& stream_label, EncryptionKey* key) override;
   Status GetKey(const std::vector<uint8_t>& key_id,
                 EncryptionKey* key) override;
   Status GetCryptoPeriodKey(uint32_t crypto_period_index,
-                            TrackType track_type,
+                            const std::string& stream_label,
                             EncryptionKey* key) override;
   /// @}
   virtual Status FetchKeysWithProgramIdentifier(const std::string& program_identifier);
diff --git a/packager/media/base/widevine_key_source.cc b/packager/media/base/widevine_key_source.cc
index 57df7e7f90..49be200a85 100644
--- a/packager/media/base/widevine_key_source.cc
+++ b/packager/media/base/widevine_key_source.cc
@@ -237,13 +237,14 @@ Status WidevineKeySource::FetchKeys(EmeInitDataType init_data_type,
   return FetchKeysInternal(!kEnableKeyRotation, 0, widevine_classic);
 }
 
-Status WidevineKeySource::GetKey(TrackType track_type, EncryptionKey* key) {
+Status WidevineKeySource::GetKey(const std::string& stream_label,
+                                 EncryptionKey* key) {
   DCHECK(key);
-  if (encryption_key_map_.find(track_type) == encryption_key_map_.end()) {
+  if (encryption_key_map_.find(stream_label) == encryption_key_map_.end()) {
     return Status(error::INTERNAL_ERROR,
-                  "Cannot find key of type " + TrackTypeToString(track_type));
+                  "Cannot find key for '" + stream_label + "'.");
   }
-  *key = *encryption_key_map_[track_type];
+  *key = *encryption_key_map_[stream_label];
   return Status::OK;
 }
 
@@ -261,7 +262,7 @@ Status WidevineKeySource::GetKey(const std::vector<uint8_t>& key_id,
 }
 
 Status WidevineKeySource::GetCryptoPeriodKey(uint32_t crypto_period_index,
-                                             TrackType track_type,
+                                             const std::string& stream_label,
                                              EncryptionKey* key) {
   DCHECK(key_production_thread_.HasBeenStarted());
   // TODO(kqyang): This is not elegant. Consider refactoring later.
@@ -279,7 +280,7 @@ Status WidevineKeySource::GetCryptoPeriodKey(uint32_t crypto_period_index,
       key_production_started_ = true;
     }
   }
-  return GetKeyInternal(crypto_period_index, track_type, key);
+  return GetKeyInternal(crypto_period_index, stream_label, key);
 }
 
 void WidevineKeySource::set_signer(std::unique_ptr<RequestSigner> signer) {
@@ -292,12 +293,10 @@ void WidevineKeySource::set_key_fetcher(
 }
 
 Status WidevineKeySource::GetKeyInternal(uint32_t crypto_period_index,
-                                         TrackType track_type,
+                                         const std::string& stream_label,
                                          EncryptionKey* key) {
   DCHECK(key_pool_);
   DCHECK(key);
-  DCHECK_LE(track_type, NUM_VALID_TRACK_TYPES);
-  DCHECK_NE(track_type, TRACK_TYPE_UNKNOWN);
 
   std::shared_ptr<EncryptionKeyMap> encryption_key_map;
   Status status = key_pool_->Peek(crypto_period_index, &encryption_key_map,
@@ -310,11 +309,11 @@ Status WidevineKeySource::GetKeyInternal(uint32_t crypto_period_index,
     return status;
   }
 
-  if (encryption_key_map->find(track_type) == encryption_key_map->end()) {
+  if (encryption_key_map->find(stream_label) == encryption_key_map->end()) {
     return Status(error::INTERNAL_ERROR,
-                  "Cannot find key of type " + TrackTypeToString(track_type));
+                  "Cannot find key for '" + stream_label + "'.");
   }
-  *key = *encryption_key_map->at(track_type);
+  *key = *encryption_key_map->at(stream_label);
   return Status::OK;
 }
 
@@ -545,11 +544,9 @@ bool WidevineKeySource::ExtractEncryptionKey(
       }
     }
 
-    std::string track_type_str;
-    RCHECK(track_dict->GetString("type", &track_type_str));
-    TrackType track_type = GetTrackTypeFromString(track_type_str);
-    DCHECK_NE(TRACK_TYPE_UNKNOWN, track_type);
-    RCHECK(encryption_key_map.find(track_type) == encryption_key_map.end());
+    std::string stream_label;
+    RCHECK(track_dict->GetString("type", &stream_label));
+    RCHECK(encryption_key_map.find(stream_label) == encryption_key_map.end());
 
     std::unique_ptr<EncryptionKey> encryption_key(new EncryptionKey());
 
@@ -573,7 +570,7 @@ bool WidevineKeySource::ExtractEncryptionKey(
 
       encryption_key->key_system_info.push_back(info);
     }
-    encryption_key_map[track_type] = std::move(encryption_key);
+    encryption_key_map[stream_label] = std::move(encryption_key);
   }
 
   // If the flag exists, create a common system ID PSSH box that contains the
diff --git a/packager/media/base/widevine_key_source.h b/packager/media/base/widevine_key_source.h
index 65a60f43e3..2e57f12bd0 100644
--- a/packager/media/base/widevine_key_source.h
+++ b/packager/media/base/widevine_key_source.h
@@ -39,11 +39,11 @@ class WidevineKeySource : public KeySource {
   /// @{
   Status FetchKeys(EmeInitDataType init_data_type,
                    const std::vector<uint8_t>& init_data) override;
-  Status GetKey(TrackType track_type, EncryptionKey* key) override;
+  Status GetKey(const std::string& stream_label, EncryptionKey* key) override;
   Status GetKey(const std::vector<uint8_t>& key_id,
                 EncryptionKey* key) override;
   Status GetCryptoPeriodKey(uint32_t crypto_period_index,
-                            TrackType track_type,
+                            const std::string& stream_label,
                             EncryptionKey* key) override;
   /// @}
 
@@ -68,13 +68,14 @@ class WidevineKeySource : public KeySource {
   void set_key_fetcher(std::unique_ptr<KeyFetcher> key_fetcher);
 
  private:
-  typedef std::map<TrackType, std::unique_ptr<EncryptionKey>> EncryptionKeyMap;
+  typedef std::map<std::string, std::unique_ptr<EncryptionKey>>
+      EncryptionKeyMap;
   typedef ProducerConsumerQueue<std::shared_ptr<EncryptionKeyMap>>
       EncryptionKeyQueue;
 
   // Internal routine for getting keys.
   Status GetKeyInternal(uint32_t crypto_period_index,
-                        TrackType track_type,
+                        const std::string& stream_label,
                         EncryptionKey* key);
 
   // The closure task to fetch keys repeatedly.
diff --git a/packager/media/base/widevine_key_source_unittest.cc b/packager/media/base/widevine_key_source_unittest.cc
index b9d8ebf203..6490ae3bba 100644
--- a/packager/media/base/widevine_key_source_unittest.cc
+++ b/packager/media/base/widevine_key_source_unittest.cc
@@ -197,17 +197,14 @@ class WidevineKeySourceTest : public Test {
 
   void VerifyKeys(bool classic) {
     EncryptionKey encryption_key;
-    const std::string kTrackTypes[] = {"SD", "HD", "UHD1", "UHD2", "AUDIO"};
-    for (size_t i = 0; i < arraysize(kTrackTypes); ++i) {
-      ASSERT_OK(widevine_key_source_->GetKey(
-          KeySource::GetTrackTypeFromString(kTrackTypes[i]),
-          &encryption_key));
-      EXPECT_EQ(GetMockKey(kTrackTypes[i]), ToString(encryption_key.key));
+    const std::string kStreamLabels[] = {"SD", "HD", "UHD1", "UHD2", "AUDIO"};
+    for (const std::string& stream_label : kStreamLabels) {
+      ASSERT_OK(widevine_key_source_->GetKey(stream_label, &encryption_key));
+      EXPECT_EQ(GetMockKey(stream_label), ToString(encryption_key.key));
       if (!classic) {
         ASSERT_EQ(add_common_pssh_ ? 2u : 1u,
                   encryption_key.key_system_info.size());
-        EXPECT_EQ(GetMockKeyId(kTrackTypes[i]),
-                  ToString(encryption_key.key_id));
+        EXPECT_EQ(GetMockKeyId(stream_label), ToString(encryption_key.key_id));
         EXPECT_EQ(GetMockPsshData(),
                   ToString(encryption_key.key_system_info[0].pssh_data()));
 
@@ -220,10 +217,10 @@ class WidevineKeySourceTest : public Test {
 
           const std::vector<std::vector<uint8_t>>& key_ids =
               encryption_key.key_system_info[1].key_ids();
-          ASSERT_EQ(arraysize(kTrackTypes), key_ids.size());
-          for (size_t j = 0; j < arraysize(kTrackTypes); ++j) {
+          ASSERT_EQ(arraysize(kStreamLabels), key_ids.size());
+          for (const std::string& stream_label : kStreamLabels) {
             // Because they are stored in a std::set, the order may change.
-            const std::string key_id_str = GetMockKeyId(kTrackTypes[j]);
+            const std::string key_id_str = GetMockKeyId(stream_label);
             const std::vector<uint8_t> key_id(key_id_str.begin(),
                                               key_id_str.end());
             EXPECT_THAT(key_ids, testing::Contains(key_id));
@@ -243,21 +240,6 @@ class WidevineKeySourceTest : public Test {
   DISALLOW_COPY_AND_ASSIGN(WidevineKeySourceTest);
 };
 
-TEST_F(WidevineKeySourceTest, GetTrackTypeFromString) {
-  EXPECT_EQ(KeySource::TRACK_TYPE_SD,
-            KeySource::GetTrackTypeFromString("SD"));
-  EXPECT_EQ(KeySource::TRACK_TYPE_HD,
-            KeySource::GetTrackTypeFromString("HD"));
-  EXPECT_EQ(KeySource::TRACK_TYPE_UHD1,
-            KeySource::GetTrackTypeFromString("UHD1"));
-  EXPECT_EQ(KeySource::TRACK_TYPE_UHD2,
-            KeySource::GetTrackTypeFromString("UHD2"));
-  EXPECT_EQ(KeySource::TRACK_TYPE_AUDIO,
-            KeySource::GetTrackTypeFromString("AUDIO"));
-  EXPECT_EQ(KeySource::TRACK_TYPE_UNKNOWN,
-            KeySource::GetTrackTypeFromString("FOO"));
-}
-
 TEST_F(WidevineKeySourceTest, GenerateSignatureFailure) {
   EXPECT_CALL(*mock_request_signer_, GenerateSignature(_, _))
       .WillOnce(Return(false));
@@ -531,23 +513,19 @@ TEST_P(WidevineKeySourceParameterizedTest, KeyRotationTest) {
   ASSERT_OK(widevine_key_source_->FetchKeys(content_id_, kPolicy));
 
   EncryptionKey encryption_key;
+  const std::string kStreamLabels[] = {"SD", "HD", "UHD1", "UHD2", "AUDIO"};
   for (size_t i = 0; i < arraysize(kCryptoPeriodIndexes); ++i) {
-    const std::string kTrackTypes[] = {"SD", "HD", "UHD1", "UHD2", "AUDIO"};
-    for (size_t j = 0; j < 5; ++j) {
+    for (const std::string& stream_label : kStreamLabels) {
       ASSERT_OK(widevine_key_source_->GetCryptoPeriodKey(
-          kCryptoPeriodIndexes[i],
-          KeySource::GetTrackTypeFromString(kTrackTypes[j]),
-          &encryption_key));
-      EXPECT_EQ(GetMockKey(kTrackTypes[j], kCryptoPeriodIndexes[i]),
+          kCryptoPeriodIndexes[i], stream_label, &encryption_key));
+      EXPECT_EQ(GetMockKey(stream_label, kCryptoPeriodIndexes[i]),
                 ToString(encryption_key.key));
     }
   }
 
   // The old crypto period indexes should have been garbage collected.
   Status status = widevine_key_source_->GetCryptoPeriodKey(
-      kFirstCryptoPeriodIndex,
-      KeySource::TRACK_TYPE_SD,
-      &encryption_key);
+      kFirstCryptoPeriodIndex, kStreamLabels[0], &encryption_key);
   EXPECT_EQ(error::INVALID_ARGUMENT, status.error_code());
 }
 
diff --git a/packager/media/crypto/encryption_handler.cc b/packager/media/crypto/encryption_handler.cc
index ec5855c118..96801635cc 100644
--- a/packager/media/crypto/encryption_handler.cc
+++ b/packager/media/crypto/encryption_handler.cc
@@ -56,18 +56,7 @@ uint8_t GetNaluLengthSize(const StreamInfo& stream_info) {
   return video_stream_info.nalu_length_size();
 }
 
-// TODO(kqyang): Update KeySource to accept string base stream label.
-KeySource::TrackType ToTrackType(const std::string& track_type) {
-  if (track_type == "SD")
-    return KeySource::TRACK_TYPE_SD;
-  if (track_type == "HD")
-    return KeySource::TRACK_TYPE_HD;
-  if (track_type == "AUDIO")
-    return KeySource::TRACK_TYPE_AUDIO;
-  return KeySource::TRACK_TYPE_SD;
-}
-
-KeySource::TrackType GetTrackTypeForEncryption(
+std::string GetStreamLabelForEncryption(
     const StreamInfo& stream_info,
     const std::function<std::string(
         const EncryptionParams::EncryptedStreamAttributes& stream_attributes)>&
@@ -84,7 +73,7 @@ KeySource::TrackType GetTrackTypeForEncryption(
     stream_attributes.oneof.video.width = video_stream_info.width();
     stream_attributes.oneof.video.height = video_stream_info.height();
   }
-  return ToTrackType(stream_label_func(stream_attributes));
+  return stream_label_func(stream_attributes);
 }
 }  // namespace
 
@@ -151,7 +140,7 @@ Status EncryptionHandler::ProcessStreamInfo(StreamInfo* stream_info) {
       stream_info->time_scale();
   codec_ = stream_info->codec();
   nalu_length_size_ = GetNaluLengthSize(*stream_info);
-  track_type_ = GetTrackTypeForEncryption(
+  stream_label_ = GetStreamLabelForEncryption(
       *stream_info, encryption_options_.stream_label_func);
   switch (codec_) {
     case kCodecVP9:
@@ -195,7 +184,7 @@ Status EncryptionHandler::ProcessStreamInfo(StreamInfo* stream_info) {
     // convenience.
     encryption_key.key = encryption_key.key_id;
   } else {
-    status = key_source_->GetKey(track_type_, &encryption_key);
+    status = key_source_->GetKey(stream_label_, &encryption_key);
     if (!status.ok())
       return status;
   }
@@ -228,7 +217,7 @@ Status EncryptionHandler::ProcessMediaSample(MediaSample* sample) {
     if (current_crypto_period_index != prev_crypto_period_index_) {
       EncryptionKey encryption_key;
       Status status = key_source_->GetCryptoPeriodKey(
-          current_crypto_period_index, track_type_, &encryption_key);
+          current_crypto_period_index, stream_label_, &encryption_key);
       if (!status.ok())
         return status;
       if (!CreateEncryptor(encryption_key))
diff --git a/packager/media/crypto/encryption_handler.h b/packager/media/crypto/encryption_handler.h
index 5c795cf7f6..e81ee2883b 100644
--- a/packager/media/crypto/encryption_handler.h
+++ b/packager/media/crypto/encryption_handler.h
@@ -78,7 +78,7 @@ class EncryptionHandler : public MediaHandler {
 
   const EncryptionOptions encryption_options_;
   KeySource* key_source_ = nullptr;
-  KeySource::TrackType track_type_ = KeySource::TRACK_TYPE_UNKNOWN;
+  std::string stream_label_;
   // Current encryption config and encryptor.
   std::shared_ptr<EncryptionConfig> encryption_config_;
   std::unique_ptr<AesCryptor> encryptor_;
diff --git a/packager/media/crypto/encryption_handler_unittest.cc b/packager/media/crypto/encryption_handler_unittest.cc
index edafd6a394..f5a58b310e 100644
--- a/packager/media/crypto/encryption_handler_unittest.cc
+++ b/packager/media/crypto/encryption_handler_unittest.cc
@@ -56,10 +56,11 @@ const uint8_t kKeyRotationDefaultKeyId[] = {
 
 class MockKeySource : public FixedKeySource {
  public:
-  MOCK_METHOD2(GetKey, Status(TrackType track_type, EncryptionKey* key));
+  MOCK_METHOD2(GetKey,
+               Status(const std::string& stream_label, EncryptionKey* key));
   MOCK_METHOD3(GetCryptoPeriodKey,
                Status(uint32_t crypto_period_index,
-                      TrackType track_type,
+                      const std::string& stream_label,
                       EncryptionKey* key));
 };
 
@@ -657,7 +658,7 @@ TEST_F(EncryptionHandlerTrackTypeTest, AudioTrackType) {
         return kAudioStreamLabel;
       };
   SetUpEncryptionHandler(encryption_options);
-  EXPECT_CALL(mock_key_source_, GetKey(KeySource::TRACK_TYPE_AUDIO, _))
+  EXPECT_CALL(mock_key_source_, GetKey(kAudioStreamLabel, _))
       .WillOnce(
           DoAll(SetArgPointee<1>(GetMockEncryptionKey()), Return(Status::OK)));
   ASSERT_OK(Process(GetAudioStreamInfoStreamData(kStreamIndex, kTimeScale)));
@@ -676,7 +677,7 @@ TEST_F(EncryptionHandlerTrackTypeTest, VideoTrackType) {
         return kSdVideoStreamLabel;
       };
   SetUpEncryptionHandler(encryption_options);
-  EXPECT_CALL(mock_key_source_, GetKey(KeySource::TRACK_TYPE_SD, _))
+  EXPECT_CALL(mock_key_source_, GetKey(kSdVideoStreamLabel, _))
       .WillOnce(
           DoAll(SetArgPointee<1>(GetMockEncryptionKey()), Return(Status::OK)));
   std::unique_ptr<StreamData> stream_data =
diff --git a/packager/media/formats/wvm/wvm_media_parser.cc b/packager/media/formats/wvm/wvm_media_parser.cc
index 5d13b3ff1e..e419c6b2f2 100644
--- a/packager/media/formats/wvm/wvm_media_parser.cc
+++ b/packager/media/formats/wvm/wvm_media_parser.cc
@@ -1076,8 +1076,8 @@ bool WvmMediaParser::GetAssetKey(const uint8_t* asset_id,
     return false;
   }
 
-  status = decryption_key_source_->GetKey(KeySource::TRACK_TYPE_HD,
-                                          encryption_key);
+  const char kHdStreamLabel[] = "HD";
+  status = decryption_key_source_->GetKey(kHdStreamLabel, encryption_key);
   if (!status.ok()) {
     LOG(ERROR) << "Fetch Key(s) failed for AssetID = "
                << ntohlFromBuffer(asset_id) << ", error = " << status;
diff --git a/packager/media/formats/wvm/wvm_media_parser_unittest.cc b/packager/media/formats/wvm/wvm_media_parser_unittest.cc
index b7ddf5cc22..47265bc034 100644
--- a/packager/media/formats/wvm/wvm_media_parser_unittest.cc
+++ b/packager/media/formats/wvm/wvm_media_parser_unittest.cc
@@ -55,8 +55,8 @@ class MockKeySource : public FixedKeySource {
   MOCK_METHOD2(FetchKeys,
                Status(EmeInitDataType init_data_type,
                       const std::vector<uint8_t>& init_data));
-  MOCK_METHOD2(GetKey, Status(TrackType track_type,
-                              EncryptionKey* key));
+  MOCK_METHOD2(GetKey,
+               Status(const std::string& stream_label, EncryptionKey* key));
 
  private:
   DISALLOW_COPY_AND_ASSIGN(MockKeySource);