--- a/dom/media/platforms/wrappers/H264Converter.cpp
+++ b/dom/media/platforms/wrappers/H264Converter.cpp
@@ -29,16 +29,21 @@ H264Converter::H264Converter(PlatformDec
   , mDecoder(nullptr)
   , mGMPCrashHelper(aParams.mCrashHelper)
   , mLastError(NS_OK)
   , mType(aParams.mType)
   , mOnWaitingForKeyEvent(aParams.mOnWaitingForKeyEvent)
   , mDecoderOptions(aParams.mOptions)
 {
   CreateDecoder(mOriginalConfig, aParams.mDiagnostics);
+  if (mDecoder) {
+    MOZ_ASSERT(mp4_demuxer::AnnexB::HasSPS(mOriginalConfig.mExtraData));
+    // The video metadata contains out of band SPS/PPS (AVC1) store it.
+    mOriginalExtraData = mOriginalConfig.mExtraData;
+  }
 }
 
 H264Converter::~H264Converter()
 {
 }
 
 RefPtr<MediaDataDecoder::InitPromise>
 H264Converter::Init()
@@ -323,19 +328,34 @@ H264Converter::DecodeFirstSample(MediaRa
     ->Track(mDecodePromiseRequest);
 }
 
 nsresult
 H264Converter::CheckForSPSChange(MediaRawData* aSample)
 {
   RefPtr<MediaByteBuffer> extra_data =
     mp4_demuxer::AnnexB::ExtractExtraData(aSample);
-  if (!mp4_demuxer::AnnexB::HasSPS(extra_data)
-      || mp4_demuxer::AnnexB::CompareExtraData(extra_data,
-                                               mCurrentConfig.mExtraData)) {
+  if (!mp4_demuxer::AnnexB::HasSPS(extra_data)) {
+    MOZ_ASSERT(mCanRecycleDecoder.isSome());
+    if (!*mCanRecycleDecoder) {
+      // If the decoder can't be recycled, the out of band extradata will never
+      // change as the H264Converter will be recreated by the MediaFormatReader
+      // instead. So there's no point in testing for changes.
+      return NS_OK;
+    }
+    // This sample doesn't contain inband SPS/PPS
+    // We now check if the out of band one has changed.
+    if (mp4_demuxer::AnnexB::HasSPS(aSample->mExtraData) &&
+        !mp4_demuxer::AnnexB::CompareExtraData(aSample->mExtraData,
+                                               mOriginalExtraData)) {
+      extra_data = mOriginalExtraData = aSample->mExtraData;
+    }
+  }
+  if (mp4_demuxer::AnnexB::CompareExtraData(extra_data,
+                                            mCurrentConfig.mExtraData)) {
     return NS_OK;
   }
 
   RefPtr<MediaRawData> sample = aSample;
   MOZ_ASSERT(mCanRecycleDecoder.isSome());
   if (*mCanRecycleDecoder) {
     // Do not recreate the decoder, reuse it.
     UpdateConfigFromExtraData(extra_data);

--- a/dom/media/platforms/wrappers/H264Converter.h
+++ b/dom/media/platforms/wrappers/H264Converter.h
@@ -76,16 +76,18 @@ private:
 
   bool CanRecycleDecoder() const;
 
   void DecodeFirstSample(MediaRawData* aSample);
 
   RefPtr<PlatformDecoderModule> mPDM;
   const VideoInfo mOriginalConfig;
   VideoInfo mCurrentConfig;
+  // Current out of band extra data (as found in metadata's VideoInfo).
+  RefPtr<MediaByteBuffer> mOriginalExtraData;
   RefPtr<layers::KnowsCompositor> mKnowsCompositor;
   RefPtr<layers::ImageContainer> mImageContainer;
   const RefPtr<TaskQueue> mTaskQueue;
   RefPtr<MediaRawData> mPendingSample;
   RefPtr<MediaDataDecoder> mDecoder;
   MozPromiseRequestHolder<InitPromise> mInitPromiseRequest;
   MozPromiseRequestHolder<DecodePromise> mDecodePromiseRequest;
   MozPromiseHolder<DecodePromise> mDecodePromise;