Movies App Won't Properly Play 5.1 Surround Sound Anymore
I have an Apple TV v4 connected directly via HDMI to a Yahama RX-V479 receiver, and have recently noticed that purchased & rented movies are no longer playing in 5.1 surround sound. All other apps play multichannel sound just fine (i.e. Netflix) - it seems to be only the Movies app that is having playback issues.
The ATV is configured properly to output uncompressed 5.1 LPCM:
Settings > Audio and Video > Surround Sound > Best Quality Available
Based on Apple's support article (About surround sound settings on your Apple TV (4th generation) - Apple Support) this should result in an uncompressed 5.1 LPCM signal, since I am connected via HDMI and my receiver supports this.
When playing surround sound content in any other app (like Netflix), this works as expected. The receiver detects the uncompressed 5.1 LPCM signal and plays the multitrack output just fine. The display on the receiver indicates it is receiving a 5.1 LPCM signal. I hear surround sound played thru all the speakers. All is well.
But when I play back any purchased or rented movies from the Movies app that have 5.1 surround sound, the output is limited to 2 channels. The receiver shows a 2.1 channel LPCM source and there is no sound from the rear speakers. I cannot get the Movies app to play any content in 5.1 surround, even though I have previously purchased movies that are clearly 5.1 and used to work just fine. This is even the case for trailers played on the Movies app, some of which I know are in 5.1 surround.
As an experiment, I tried setting the ATV to output 5.1 Dolby Digital to see the affect:
Settings > Audio and Video > Surround Sound > Dolby Digital 5.1
As expected, Netflix works just fine. The receiver detects, displays, and outputs a 5.1 Dolby Digital signal and it plays properly on all speakers. Playing movies thru the Movies app *still* only outputs 2.1 channel LPCM. It doesn't output Dolby Digital at all.
As I said, every other app on the ATV behaves properly, so I don't think it is an issue with the ATV settings or the receiver. It only occurs with the Movies app and content that is streaming from the iTunes store (either rented or purchased). It's as if the Movies app has suddenly lost the ability to properly output surround sound. Has anyone else seen this kind of behaviour lately? Could this be a bug introduced in a recent update or an issue with content streaming from Apple?
Apple TV, tvOS
