Bug 1668824 - On macOS and Windows, prefer ffmpeg to decode mp3s. r=jya

Differential Revision: https://phabricator.services.mozilla.com/D92235

dom/media/platforms/apple/AppleDecoderModule.cpp

@@ -14,6 +14,7 @@
 #include "VPXDecoder.h"
 #include "mozilla/DebugOnly.h"
 #include "mozilla/Logging.h"
+#include "mozilla/StaticPrefs_media.h"
 #include "mozilla/gfx/gfxVars.h"
 
 extern "C" {
@@ -73,7 +74,8 @@ already_AddRefed<MediaDataDecoder> AppleDecoderModule::CreateAudioDecoder(
 
 bool AppleDecoderModule::SupportsMimeType(
     const nsACString& aMimeType, DecoderDoctorDiagnostics* aDiagnostics) const {
-  return aMimeType.EqualsLiteral("audio/mpeg") ||
+  return (aMimeType.EqualsLiteral("audio/mpeg") &&
+          !StaticPrefs::media_ffvpx_mp3_enabled()) ||
          aMimeType.EqualsLiteral("audio/mp4a-latm") ||
          MP4Decoder::IsH264(aMimeType) || VPXDecoder::IsVP9(aMimeType);
 }

dom/media/platforms/wmf/WMFDecoderModule.cpp

@@ -210,6 +210,7 @@ bool WMFDecoderModule::Supports(const TrackInfo& aTrackInfo,
     return true;
   }
   if (aTrackInfo.mMimeType.EqualsLiteral("audio/mpeg") &&
+      !StaticPrefs::media_ffvpx_mp3_enabled() &&
       CanCreateWMFDecoder<CLSID_CMP3DecMediaObject>()) {
     return true;
   }