diff --git a/dom/media/platforms/PDMFactory.cpp b/dom/media/platforms/PDMFactory.cpp
index f14b8a0bd5d..54006762716 100644
--- a/dom/media/platforms/PDMFactory.cpp
+++ b/dom/media/platforms/PDMFactory.cpp
@@ -32,9 +32,7 @@
 #include "FuzzingWrapper.h"
 #include "H264Converter.h"
 
-#include "OpusDecoder.h"
-#include "VorbisDecoder.h"
-#include "VPXDecoder.h"
+#include "AgnosticDecoderModule.h"
 
 namespace mozilla {
 
@@ -112,22 +110,15 @@ PDMFactory::CreateDecoder(const TrackInfo& aConfig,
                           layers::ImageContainer* aImageContainer)
 {
   nsRefPtr<PlatformDecoderModule> current = GetDecoder(aConfig.mMimeType);
+  if (!current) {
+    return nullptr;
+  }
   nsRefPtr<MediaDataDecoder> m;
 
   if (aConfig.GetAsAudioInfo()) {
-    if (!current && VorbisDataDecoder::IsVorbis(aConfig.mMimeType)) {
-      m = new VorbisDataDecoder(*aConfig.GetAsAudioInfo(),
-                                aTaskQueue,
-                                aCallback);
-    } else if (!current && OpusDataDecoder::IsOpus(aConfig.mMimeType)) {
-      m = new OpusDataDecoder(*aConfig.GetAsAudioInfo(),
-                              aTaskQueue,
-                              aCallback);
-    } else if (current) {
-      m = current->CreateAudioDecoder(*aConfig.GetAsAudioInfo(),
+    m = current->CreateAudioDecoder(*aConfig.GetAsAudioInfo(),
                                       aTaskQueue,
                                       aCallback);
-    }
     return m.forget();
   }
 
@@ -145,34 +136,27 @@ PDMFactory::CreateDecoder(const TrackInfo& aConfig,
     callback = callbackWrapper.get();
   }
 
-  if (!current && VPXDecoder::IsVPX(aConfig.mMimeType)) {
-    m = new VPXDecoder(*aConfig.GetAsVideoInfo(),
-                       aImageContainer,
-                       aTaskQueue,
-                       callback);
-  } else if (current) {
-    if (H264Converter::IsH264(aConfig)) {
-      nsRefPtr<H264Converter> h
-        = new H264Converter(current,
-                            *aConfig.GetAsVideoInfo(),
-                            aLayersBackend,
-                            aImageContainer,
-                            aTaskQueue,
-                            callback);
-      const nsresult rv = h->GetLastError();
-      if (NS_SUCCEEDED(rv) || rv == NS_ERROR_NOT_INITIALIZED) {
-        // The H264Converter either successfully created the wrapped decoder,
-        // or there wasn't enough AVCC data to do so. Otherwise, there was some
-        // problem, for example WMF DLLs were missing.
-        m = h.forget();
-      }
-    } else {
-      m = current->CreateVideoDecoder(*aConfig.GetAsVideoInfo(),
-                                      aLayersBackend,
-                                      aImageContainer,
-                                      aTaskQueue,
-                                      callback);
+  if (H264Converter::IsH264(aConfig)) {
+    nsRefPtr<H264Converter> h
+      = new H264Converter(current,
+                          *aConfig.GetAsVideoInfo(),
+                          aLayersBackend,
+                          aImageContainer,
+                          aTaskQueue,
+                          callback);
+    const nsresult rv = h->GetLastError();
+    if (NS_SUCCEEDED(rv) || rv == NS_ERROR_NOT_INITIALIZED) {
+      // The H264Converter either successfully created the wrapped decoder,
+      // or there wasn't enough AVCC data to do so. Otherwise, there was some
+      // problem, for example WMF DLLs were missing.
+      m = h.forget();
     }
+  } else {
+    m = current->CreateVideoDecoder(*aConfig.GetAsVideoInfo(),
+                                    aLayersBackend,
+                                    aImageContainer,
+                                    aTaskQueue,
+                                    callback);
   }
 
   if (callbackWrapper && m) {
@@ -186,10 +170,7 @@ bool
 PDMFactory::SupportsMimeType(const nsACString& aMimeType)
 {
   nsRefPtr<PlatformDecoderModule> current = GetDecoder(aMimeType);
-  return current ||
-    VPXDecoder::IsVPX(aMimeType) ||
-    OpusDataDecoder::IsOpus(aMimeType) ||
-    VorbisDataDecoder::IsVorbis(aMimeType);
+  return !!current;
 }
 
 void
@@ -231,6 +212,10 @@ PDMFactory::CreatePDMs()
     StartupPDM(m);
   }
 #endif
+
+  m = new AgnosticDecoderModule();
+  StartupPDM(m);
+
   if (sUseBlankDecoder) {
     m = CreateBlankDecoderModule();
     StartupPDM(m);
diff --git a/dom/media/platforms/agnostic/AgnosticDecoderModule.cpp b/dom/media/platforms/agnostic/AgnosticDecoderModule.cpp
new file mode 100644
index 00000000000..c877e80f392
--- /dev/null
+++ b/dom/media/platforms/agnostic/AgnosticDecoderModule.cpp
@@ -0,0 +1,61 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "AgnosticDecoderModule.h"
+#include "OpusDecoder.h"
+#include "VorbisDecoder.h"
+#include "VPXDecoder.h"
+
+namespace mozilla {
+
+bool
+AgnosticDecoderModule::SupportsMimeType(const nsACString& aMimeType)
+{
+  return VPXDecoder::IsVPX(aMimeType) ||
+    OpusDataDecoder::IsOpus(aMimeType) ||
+    VorbisDataDecoder::IsVorbis(aMimeType);
+}
+
+already_AddRefed<MediaDataDecoder>
+AgnosticDecoderModule::CreateVideoDecoder(const VideoInfo& aConfig,
+                                          layers::LayersBackend aLayersBackend,
+                                          layers::ImageContainer* aImageContainer,
+                                          FlushableTaskQueue* aVideoTaskQueue,
+                                          MediaDataDecoderCallback* aCallback)
+{
+  nsRefPtr<MediaDataDecoder> m;
+
+  if (VPXDecoder::IsVPX(aConfig.mMimeType)) {
+    m = new VPXDecoder(*aConfig.GetAsVideoInfo(),
+                       aImageContainer,
+                       aVideoTaskQueue,
+                       aCallback);
+  }
+
+  return m.forget();
+}
+
+already_AddRefed<MediaDataDecoder>
+AgnosticDecoderModule::CreateAudioDecoder(const AudioInfo& aConfig,
+                                          FlushableTaskQueue* aAudioTaskQueue,
+                                          MediaDataDecoderCallback* aCallback)
+{
+  nsRefPtr<MediaDataDecoder> m;
+
+  if (VorbisDataDecoder::IsVorbis(aConfig.mMimeType)) {
+    m = new VorbisDataDecoder(*aConfig.GetAsAudioInfo(),
+                              aAudioTaskQueue,
+                              aCallback);
+  } else if (OpusDataDecoder::IsOpus(aConfig.mMimeType)) {
+    m = new OpusDataDecoder(*aConfig.GetAsAudioInfo(),
+                            aAudioTaskQueue,
+                            aCallback);
+  }
+
+  return m.forget();
+}
+
+} // namespace mozilla
diff --git a/dom/media/platforms/agnostic/AgnosticDecoderModule.h b/dom/media/platforms/agnostic/AgnosticDecoderModule.h
new file mode 100644
index 00000000000..97cc23e799b
--- /dev/null
+++ b/dom/media/platforms/agnostic/AgnosticDecoderModule.h
@@ -0,0 +1,39 @@
+#if !defined(AgnosticDecoderModule_h_)
+#define AgnosticDecoderModule_h_
+
+#include "PlatformDecoderModule.h"
+
+namespace mozilla {
+
+class AgnosticDecoderModule : public PlatformDecoderModule {
+public:
+  AgnosticDecoderModule() = default;
+  virtual ~AgnosticDecoderModule() = default;
+
+  bool SupportsMimeType(const nsACString& aMimeType) override;
+
+  ConversionRequired
+  DecoderNeedsConversion(const TrackInfo& aConfig) const override
+  {
+    return ConversionRequired::kNeedNone;
+  }
+
+protected:
+  // Decode thread.
+  already_AddRefed<MediaDataDecoder>
+  CreateVideoDecoder(const VideoInfo& aConfig,
+                     layers::LayersBackend aLayersBackend,
+                     layers::ImageContainer* aImageContainer,
+                     FlushableTaskQueue* aVideoTaskQueue,
+                     MediaDataDecoderCallback* aCallback) override;
+
+  // Decode thread.
+  already_AddRefed<MediaDataDecoder>
+  CreateAudioDecoder(const AudioInfo& aConfig,
+                     FlushableTaskQueue* aAudioTaskQueue,
+                     MediaDataDecoderCallback* aCallback) override;
+};
+
+} // namespace mozilla
+
+#endif /* AgnosticDecoderModule_h_ */
diff --git a/dom/media/platforms/agnostic/BlankDecoderModule.cpp b/dom/media/platforms/agnostic/BlankDecoderModule.cpp
index f176055f59d..5b6e788f296 100644
--- a/dom/media/platforms/agnostic/BlankDecoderModule.cpp
+++ b/dom/media/platforms/agnostic/BlankDecoderModule.cpp
@@ -259,27 +259,10 @@ public:
 
 };
 
-class AgnosticDecoderModule : public BlankDecoderModule {
-public:
-
-  bool SupportsMimeType(const nsACString& aMimeType) override
-  {
-    // This module does not support any decoders itself,
-    // agnostic decoders are created in PlatformDecoderModule::CreateDecoder
-    return false;
-  }
-};
-
 already_AddRefed<PlatformDecoderModule> CreateBlankDecoderModule()
 {
   nsRefPtr<PlatformDecoderModule> pdm = new BlankDecoderModule();
   return pdm.forget();
 }
 
-already_AddRefed<PlatformDecoderModule> CreateAgnosticDecoderModule()
-{
-  nsRefPtr<PlatformDecoderModule> adm = new AgnosticDecoderModule();
-  return adm.forget();
-}
-
 } // namespace mozilla
diff --git a/dom/media/platforms/moz.build b/dom/media/platforms/moz.build
index ae84d1f0144..8a217ce267c 100644
--- a/dom/media/platforms/moz.build
+++ b/dom/media/platforms/moz.build
@@ -5,6 +5,7 @@
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 EXPORTS += [
+    'agnostic/AgnosticDecoderModule.h',
     'agnostic/OpusDecoder.h',
     'agnostic/VorbisDecoder.h',
     'agnostic/VPXDecoder.h',
@@ -14,6 +15,7 @@ EXPORTS += [
 ]
 
 UNIFIED_SOURCES += [
+    'agnostic/AgnosticDecoderModule.cpp',
     'agnostic/BlankDecoderModule.cpp',
     'agnostic/OpusDecoder.cpp',
     'agnostic/VorbisDecoder.cpp',