--- a/dom/media/MediaFormatReader.cpp
+++ b/dom/media/MediaFormatReader.cpp
@@ -283,16 +283,17 @@ MediaFormatReader::OnDemuxerInitDone(nsr
         // We have no decoder for this track. Error.
         mMetadataPromise.Reject(NS_ERROR_DOM_MEDIA_METADATA_ERR, __func__);
         return;
       }
       mInfo.mVideo = *videoInfo->GetAsVideoInfo();
       for (const MetadataTag& tag : videoInfo->mTags) {
         tags->Put(tag.mKey, tag.mValue);
       }
+      mVideo.mOriginalInfo = Move(videoInfo);
       mVideo.mCallback = new DecoderCallback(this, TrackInfo::kVideoTrack);
       mVideo.mTimeRanges = mVideo.mTrackDemuxer->GetBuffered();
       mTrackDemuxersMayBlock |= mVideo.mTrackDemuxer->GetSamplesMayBlock();
     } else {
       mVideo.mTrackDemuxer->BreakCycles();
       mVideo.mTrackDemuxer = nullptr;
     }
   }
@@ -311,16 +312,17 @@ MediaFormatReader::OnDemuxerInitDone(nsr
                   (!platform ||
                    platform->SupportsMimeType(audioInfo->mMimeType, nullptr));
 
     if (audioActive) {
       mInfo.mAudio = *audioInfo->GetAsAudioInfo();
       for (const MetadataTag& tag : audioInfo->mTags) {
         tags->Put(tag.mKey, tag.mValue);
       }
+      mAudio.mOriginalInfo = Move(audioInfo);
       mAudio.mCallback = new DecoderCallback(this, TrackInfo::kAudioTrack);
       mAudio.mTimeRanges = mAudio.mTrackDemuxer->GetBuffered();
       mTrackDemuxersMayBlock |= mAudio.mTrackDemuxer->GetSamplesMayBlock();
     } else {
       mAudio.mTrackDemuxer->BreakCycles();
       mAudio.mTrackDemuxer = nullptr;
     }
   }
@@ -398,31 +400,35 @@ MediaFormatReader::EnsureDecoderCreated(
 
   decoder.mDecoderInitialized = false;
 
   MonitorAutoLock mon(decoder.mMonitor);
 
   switch (aTrack) {
     case TrackType::kAudioTrack: {
       decoder.mDecoder = mPlatform->CreateDecoder({
-        decoder.mInfo ? *decoder.mInfo->GetAsAudioInfo() : mInfo.mAudio,
+        decoder.mInfo
+        ? *decoder.mInfo->GetAsAudioInfo()
+        : *decoder.mOriginalInfo->GetAsAudioInfo(),
         decoder.mTaskQueue,
         decoder.mCallback.get(),
         mCrashHelper,
         decoder.mIsBlankDecode,
         &result
       });
       break;
     }
 
     case TrackType::kVideoTrack: {
       // Decoders use the layers backend to decide if they can use hardware decoding,
       // so specify LAYERS_NONE if we want to forcibly disable it.
       decoder.mDecoder = mPlatform->CreateDecoder({
-        mVideo.mInfo ? *mVideo.mInfo->GetAsVideoInfo() : mInfo.mVideo,
+        decoder.mInfo
+        ? *decoder.mInfo->GetAsVideoInfo()
+        : *decoder.mOriginalInfo->GetAsVideoInfo(),
         decoder.mTaskQueue,
         decoder.mCallback.get(),
         mKnowsCompositor,
         GetImageContainer(),
         mCrashHelper,
         decoder.mIsBlankDecode,
         &result
       });

--- a/dom/media/MediaFormatReader.h
+++ b/dom/media/MediaFormatReader.h
@@ -420,16 +420,18 @@ private:
     // Used by the MDSM to determine if video decoding is hardware accelerated.
     // This value is updated after a frame is successfully decoded.
     Atomic<bool> mIsHardwareAccelerated;
     // Sample format monitoring.
     uint32_t mLastStreamSourceID;
     Maybe<uint32_t> mNextStreamSourceID;
     media::TimeIntervals mTimeRanges;
     Maybe<media::TimeUnit> mLastTimeRangesEnd;
+    // TrackInfo as first discovered during ReadMetadata.
+    UniquePtr<TrackInfo> mOriginalInfo;
     RefPtr<SharedTrackInfo> mInfo;
     Maybe<media::TimeUnit> mFirstDemuxedSampleTime;
     // Use BlankDecoderModule or not.
     bool mIsBlankDecode;
 
   };
 
   class DecoderDataWithPromise : public DecoderData {