tvOS cuts off beginning of Apple Music tracks w/spatial audio? (Atmos)

[JeffPerrin]

Has anyone else noticed how tvOS frequently cuts off the very beginning of songs when spatial audio is enabled? ie. Navigate to a track in Apple Music (on tvOS) and click on it to play. Pick a song you're familiar with that has a strong or percussive intro so as to hear when this happens. ("Tom Sawyer" by Rush is a good one, for example.)

 

[priitv8]

No, I haven't. But I will give it a try.
I know that gapless play has gaps, when you listen to Atmos rendering of a gapless album.

 

[waw74]

what speakers are you using?

it's possible it's the speakers, and not the appleTV.
Atmos seems to take a moment to sync up, and some speakers might be slower than others.

 

[JeffPerrin]

I've ruled out external gear. Happens both on my Denon AVR 7.1.4 systems and my Bravio (Atmos-supported) TV speakers.

Only thing left I can think of are the HDMI cables...

 

[priitv8]

Only thing left I can think of are the HDMI cables...

Do you think Atmos takes longer to travel along the copper line?
HDMI 1.4 should be fully sufficient.
It must be the lead time it takes to sync with the stream and start decoding.

 

[JeffPerrin]

Do you think Atmos takes longer to travel along the copper line?

Of course not. But you never know - stranger things have been the cause of trouble. Like I said, it's the ONLY variable left on my end I can think of to rule out.

It must be the lead time it takes to sync with the stream and start decoding.

That's what I'm thinking. But this would be a tvOS issue as the Atmos is decoded onboard the ATV. Which is why I'm asking if anyone else has noticed this. Did you happen to check into this on your set-up yet?

 

[priitv8]

That's what I'm thinking. But this would be a tvOS issue as the Atmos is decoded onboard the ATV. Which is why I'm asking if anyone else has noticed this. Did you happen to check into this on your set-up yet?

Did not have the chance yet, unfortunately. But will take my time tomorrow.
I think this is closely related to the gapless playback issue everyone is having with Atmos music tracks.
That one I have tested myself, and confirm, that I get small gaps between gapless tracks (e.g. Beatles Abbey Road 50th anniversary album).
PS, I am trying to dig a little deeper into inner workings of Atmos. I think it should not be deadly complicated to create an object visualizer for the DD+ Atmos, at least. Something like they show here:

 

[waw74]

I've got the Sonos Arc (and surrounds), If I pause a show with Atmos, when I re-start it, all of the sound comes out behind me for just a blip then the audio goes to where it's supposed to be. it seems to be all channels of audio equally out of the left and right surrounds. Same thing happens when I skip forward or back, it happens whenever playback resumes. I haven't noticed it at the beginning of shows, but it might just not be making noise.

I think Atmos takes a moment to lock in, Since it's not a straight 1 to 1 pairing between the channels and the speakers, the decoder has to receive and interpret the data to sort out where each of the "channels" are supposed to be, and where those locations relate to each of it's speakers. It's possible that in my case, sonos makes the blip, while other speakers are smart enough to mute for that split second.

in some more testing just now, it seems that happens on several apps on the appleTV with atmos, all sound comes out of the back for a blip, then it sorts itself out. (Music, Netflix, aTV+, and Disney+,). DD5.1 doesn't do it. I can pause and play at about 1 second intervals, and it does it every single time.

I can't tell If it does it when using the TV's speakers (LG CX, supports atmos on internal speakers), since they're all in the front.

I did try Tom Sawyer, it sounded like it might be cut off a little bit on the TV, but not enough that it's very noticable. it also sounds like it's doing the "all in the back" thing with sonos. but it's hard to tell

I did a test using the same apps that are built into the TV and it doesn't seem to happen.
I do have a test tone file that I can play on the TV with pink noise on each channel for a bit. it does seem to hiccup for a moment when it starts playback, but I don't have a way to play it on the aTV while preserving the audio.


and just to get it all in one place
aTV 4k - 1st gen
LG CX
Sonos Arc


The viewer in the video seems to be a companion app to the Trinnov AV line of receivers, the base model is $17,500, and they go up to $29,000. And that doesn't include Atmos, if you want to do that, it's a $2,500 add on

Audio Synthesis: Trinnov Altitude32 AV Processor

When JBL fired up the latest iteration of its state-of-the-art Synthesis system at 2015 CEDIA Expo, more than a few jaws dropped (ours included). The system mated a mind-blowing array of 32 speakers with a 17-foot-wide screen and a battery of amplifiers that delivered 10-plus kilowatts of power...

www.soundandvision.com

 

[JeffPerrin]

I've got the Sonos Arc (and surrounds), If I pause a show with Atmos, when I re-start it, all of the sound comes out behind me for just a blip then the audio goes to where it's supposed to be.

I've noticed this as well and just figure it was an Atmos quirk. Never noticed the beginning of material cut-off until Apple Music (on tvOS only, though). Thanks for the detailed report! 👍

 

[priitv8]

I've noticed this as well and just figure it was an Atmos quirk. Never noticed the beginning of material cut-off until Apple Music (on tvOS only, though). Thanks for the detailed report! 👍

I can confirm that I see the same behaviour. My AVR does not steer sound anywhere, it is just mute until it starts decoding. This phenomenon only appears when I jump to a new track. Once playing, when I jump the timeline back to beginning (0:00) i hear also the very first beats, that go missing in the virgin play of a new track.

 

[JeffPerrin]

I can confirm that I see the same behaviour. My AVR does not steer sound anywhere, it is just mute until it starts decoding. This phenomenon only appears when I jump to a new track. Once playing, when I jump the timeline back to beginning (0:00) i hear also the very first beats, that go missing in the virgin play of a new track.

Thanks for checking (and confirming!) And I should have stated above this primarily happens when "manually" selecting or jumping to a new track. Thanks for mentioning that important detail. 👍 👍

 

[cshamis]

Don’t guess! Ask an engineer!

Here’s what’s happening. Before the song starts the playback device has not established a “channel” to send the music on. So the DAC in your system, the Dolby digital, the amp, or your TV, or /whatever/ digital processors are kinda like switched “off”.

When you hit play it takes the electronics a second to realize that the digital channel has gone from “off” to “on”. This sort of thing is called “handshaking” in computer terminology; and in a modern digital audio systems there can be quite a bit of it.

Once the channel is recognized by your gear as “on” then the music will play. But sometimes the music starts before the handshake has a chance to complete and THAT is why it cuts off the first few notes. Pauses/unpause just sends digital “zeros” across the line… but the channel is still established so it’s usually instantaneous. But, if you hit “stop” then it turns off the channel and your gear has to re-handshake to start up again.

Here’s another analogy. When you first hit play on a track it’s like making a call on your phone. It takes a second for the call to go through and the other person to pickup. Pressing “mute” it’s like hitting pause. You’re still connected, but there’s no sound being transmitted. Hitting stop would be like hanging up. If you want to play something else you have to call them back.

When playing one track into another the channel is never shut off, so things just flow smoothly to the next track.

So what can be done?

Well, for starters the nice people at iTunes could restore the recordings original “lead in” from all the songs they store in the cloud. Though it might costs a few extra terabytes. But I’ll bet they save 10s of thousands of dollars doing this. Then we might not have this problem.

Or, the tvOS people at Apple could fix it by opening the audio channel and giving a slight delay of a second or two to give the gear a fighting chance to complete the handshake before they start streaming the beginning of the song. This would only have to be done for the first song.

Or, you can buy better gear. Better gear handshakes faster (or smarter) so this isn’t a problem.

Or, you could simplify your setup, instead of running your Apple TV thought your tv and then back out to your receiver which then sends it to your Bluetooth speakers… all that can add extra protocol handshakes that may take a second to get ready. Eliminating as much as possible might help.

But really, Apple could fix it really easily but they probably won’t, because I don’t think they really care anymore. Because it’s not really a hard problem.

That makes me kinda sad, but there it is.

 

[Casey Royals]

Possibly caused by the “Quick Start” setting, the song isn’t getting a chance to download enough before it begins playing. If you turn the Quick Start setting off you can’t use ATMOS ?

 

[JeffPerrin]

Or, you can buy better gear. Better gear handshakes faster (or smarter) so this isn’t a problem.

Or, you could simplify your setup, instead of running your Apple TV thought your tv and then back out to your receiver which then sends it to your Bluetooth speakers… all that can add extra protocol handshakes that may take a second to get ready. Eliminating as much as possible might help.

Running fairly recent, popular Denon AVR connected directly to ATV - no smart TV or bluetooth speakers involved. Agreed on handshake issue, but my money is firmly on this being a tvOS problem, not related to consumer-end set-up. (Have tested various set-ups, ruling out the AVR as well.)

Possibly caused by the “Quick Start” setting, the song isn’t getting a chance to download enough before it begins playing.

Not sure what you mean... Where is the Quick Start setting for tvOS?

 

[Casey Royals]

Not sure what you mean... Where is the Quick Start setting for tvOS?

see here: https://support.apple.com/en-au/HT212714

“You can't play sound in Dolby Atmos if Quick Start is turned off in Settings. To check, go to Settings > Apps > iTunes Films and TV Shows > Quick Start.”

 

[priitv8]

see here: https://support.apple.com/en-au/HT212714

“You can't play sound in Dolby Atmos if Quick Start is turned off in Settings. To check, go to Settings > Apps > iTunes Films and TV Shows > Quick Start.”

I wonder if that “quick start” is just a disguise name and actually just turns on HLS streaming?

 

[appleCakes]

I can confirm I have the same problem as priitv8 (clipping at start after stop or jumping track); high end set up, all wired, Denon receiver with HDMI 48 Gbps cable everywhere; using eARC (Apple TV direct to LG C2 TV, TV eARC HDMI to Denon receiver and then to 5.1.2 top speakers) — seems like tvOS should fix this by adding a bit delay at start.. any tips appreciated.

 

[cmorello69]

I have been chasing this problem down for a while as well. I even went as far as calling Apple TV support and being on with them for an hour. The supervisor was clueless about this and from what he read of his information, went as far to tell me that spacial audio on the Apple TV Music app was ONLY for AirPods and compatible headphones. Obviously, I didn't get any resolution from them.

I confirmed just about all that's been said here and engineer cshamis seems to have the best answer I've gotten so far. My Apple TV is high speed HDMI cabled into my Denon AVR-X4500H which would seem (for the price) to be beefy enough to quickly switch into Dolby Atmos mode fairly quickly. For me, each song takes between 1 1/2 to almost 3 seconds into the song before the receiver puts out the audio. I didn't notice until today that Dolby Atmos movies also have a couple seconds of silence before the soundtrack is audible. I suppose that if there is an AV receiver that somehow stays in Atmos between tracks, that would solve the issue for music. I don't know successful googling for that would be but I'll try when I have the chance.

Edit: doing the googling above and found another person with the problem, explanation, and my same model AV receiver. https://discussions.apple.com/thread/253877772

Final edit: Chatted with a Denon tech support person. He confirmed above that the receiver needs that time at the beginning of the streamed file to "negotiate" the signal to switch to Dolby Atmos. So, the question would be whether another receiver brand can switch much more quickly or just stay in Atmos mode some how.