--- a/dom/media/platforms/apple/AppleATDecoder.cpp
+++ b/dom/media/platforms/apple/AppleATDecoder.cpp
@@ -308,18 +308,19 @@ AppleATDecoder::DecodeSample(MediaRawDat
       duration.ToSeconds());
 #endif
 
   AudioSampleBuffer data(outputData.Elements(), outputData.Length());
   if (!data.Data()) {
     return NS_ERROR_OUT_OF_MEMORY;
   }
   if (mChannelLayout && !mAudioConverter) {
-    AudioConfig in(*mChannelLayout.get(), rate);
-    AudioConfig out(channels, rate);
+    AudioConfig in(*mChannelLayout, rate);
+    AudioConfig out(AudioConfig::ChannelLayout::SMPTEDefault(*mChannelLayout),
+                    rate);
     if (!in.IsValid() || !out.IsValid()) {
       return MediaResult(NS_ERROR_DOM_MEDIA_DECODE_ERR,
                          RESULT_DETAIL("Invalid audio config"));
     }
     mAudioConverter = MakeUnique<AudioConverter>(in, out);
   }
   if (mAudioConverter) {
     MOZ_ASSERT(mAudioConverter->CanWorkInPlace());