Off topic in Sound Science. the new old moderation.

[Ryokan]

I’ll probably delete this thread as I clearly never enforced anything I said I would. I can’t, it’s instantly too much work thanks to a billion off topics per month( number provided by the protesters).

All those moments will be lost in time, like tears in rain

 

[bigshot]

The file being played on my AirPod Max when I select Spatial Audio is not the same file you are playing when you select Atmos on your Apple TV. They may have both started as the same basic master, but they don't sound the same and they don't have the same number of channels. Yours is delivered in a proprietary multichannel Atmos file format, and mine is passed across as a lossy two channel file using bluetooth.

Spatial Audio for headphones isn't the same thing as Atmos for speakers. I can't figure out how you would argue that it is. I can only guess that you don't have AirPods and have never heard Spatial Audio playback. It's signal processing to synthesize surround sound, just like what Boom 3D does, or those fake stereo gadgets they used to sell in the 70s. It isn't a multichannel format itself.

You can't play an Atmos file on your iPhone and output it through line out to hear true multichannel Atmos on speakers. The iPhone only supports Spatial Audio output through bluetooth to AirPods or sound played back on its internal speaker. However, an Apple TV can output either true Atmos or spatial audio for headphones.

You can call Spatial Audio Atmos, but that's basically using a brand name, not a specific file format. It's a huge stretch to claim that Spatial Audio recreates the sound of a cinema. That is sales pitch. Purple prose. What it does is to open up the sound of headphones and makes it sound subjectively better. It's sophisticated signal processing that adds some semi-defined stock depth cues.

 

[Davesrose]

Again, repetition does not make something fact. An Apple Music file that's listed as Dolby Atmos is 5.1 channels and Dolby Atmos metadata. That is the same source that goes to a AVR or Apple Spatial Audio (in which a 3D sound field is simulated with multiple object tracks, to then be rendered on whatever the playback system is). I can't figure out why you continue to make these claims, even when there's been quotes presented, as well as description given by a professional who has mixed in Atmos.


What is Apple spatial audio:

"Apple spatial audio takes 5.1, 7.1 and Dolby Atmos signals and applies directional audio filters, adjusting the frequencies that each ear hears so that sounds can be placed virtually anywhere in 3D space. Sounds will appear to be coming from in front of you, from the sides, the rear and even above. The idea is to recreate the audio experience of a cinema."

 

[Ryokan]

Again, repition does not make something fact. An Apple Music file that's listed as Dolby Atmos is 5.1 channels and Dolby Atmos metadata. That is the same source that goes to a AVR or Apple Spatial Audio (in which a 3D sound field is simulated with multiple object tracks, to then be rendered on whatever the playback system is). I can't figure out why you continue to make these claims, even when there's been quotes presented, as well as description given by a professional who has mixed in Atmos.


What is Apple spatial audio:

"Apple spatial audio takes 5.1, 7.1 and Dolby Atmos signals and applies directional audio filters, adjusting the frequencies that each ear hears so that sounds can be placed virtually anywhere in 3D space. Sounds will appear to be coming from in front of you, from the sides, the rear and even above. The idea is to recreate the audio experience of a cinema."

Was Dolby Atmos designed purely for a multi speaker set up? so using headphones would be severely limiting the effect?

 

[Davesrose]

Was Dolby Atmos designed purely for a multi speaker set up? so using headphones would be severely limiting the effect?

It was designed to be able to have flexible positional audio for speakers or headphones. It's especially useful for cinemas, which previously just had arrays of speakers with the same channel. The Atmos processor first simulates a 3D sound field from the source's embedded channels and objects. It can then send a specific signal to each speaker/driver

 

[bigshot]

Was Dolby Atmos designed purely for a multi speaker set up? so using headphones would be severely limiting the effect?

Yes and yes.

When I play a Dolby Atmos song from the Apple Store on my iPhone listening with my AirPods Max, I am not listening to a 5.1 file with Atmos metadata... Because the iPhone doesn't support playback of 5.1 and I don't believe bluetooth supports metadata.

My guess is that Atmos files in the Apple Music Store for playback on speakers are AAC multichannel files and the Spatial Audio files for headphones are pre-processed 2 channel AAC files with matrixed elements that get placed by the headphones to accomplish head tracking. The iPhone or Apple TV send a flag back to the Apple Music Store to tell it what you are listening to so it sends the proper file for your playback device.

Using an Apple TV, it isn't possible to play an Atmos track on both speakers and headphones at the same time. This is probably because it would be very difficult to sync up two completely separate files.

 

[Davesrose]

Wrong again. When I bring up Apple Music on my iphone, it will list what albums are Dolby Atmos surround (which with streaming is 5.1 channels plus positional data). I can even airplay surround to my AVR. Why you continue with these claims, when quotes have been provided....


What is Apple spatial audio:

"Apple spatial audio takes 5.1, 7.1 and Dolby Atmos signals and applies directional audio filters, adjusting the frequencies that each ear hears so that sounds can be placed virtually anywhere in 3D space. Sounds will appear to be coming from in front of you, from the sides, the rear and even above. The idea is to recreate the audio experience of a cinema."

 

[Ryokan]

Yes and yes.

When I play a Dolby Atmos song from the Apple Store on my iPhone listening with my AirPods Max, I am not listening to a 5.1 file with Atmos metadata... Because the iPhone doesn't support playback of 5.1 and I don't believe bluetooth supports metadata.

My guess is that Atmos files in the Apple Music Store for playback on speakers are AAC multichannel files and the Spatial Audio files for headphones are pre-processed 2 channel AAC files with matrixed elements that get placed by the headphones to accomplish head tracking. The iPhone or Apple TV send a flag back to the Apple Music Store to tell it what you are listening to so it sends the proper file for your playback device.

That's a very complex system.

 

[Davesrose]

That's a very complex system.

One that's conjecture and not based on any written literature.

 

[bigshot]

That's a very complex system.

Apple is a walled garden, and Spatial Audio is exclusive to their own devices, so they have designed the equipment to suit the software and vice versa.

DR. you can't play 5.1 on your phone, you can only pass the file on to a device that *can* play it. The iPhone doesn't support 5.1 for playback itself. Your misunderstanding seems to be because you've never used Spatial Audio with AirPods and the iPhone. It's different than the Atmos files you are used to.

 

[Davesrose]

no, again, you're wrong bigshot. Bluetooth is a wireless data transmission protocol: it isn't just used with 2 channel stereo. It is also a Dolby Atmos certified device:
Can You Stream Dolby Atmos Music Through Airplay?

Apple is not walled off in stating that their devices are Atmos certified, and are using Dolby Atmos as a source. Here's another quote emphasizing the fact that Atmos is 5.1 with metadata. But you do you in thinking your conjectures trump actual literature

What is Apple spatial audio? How it works and how to use it
"Also important to note is that media content must be available in the 5.1, 7.1 or Dolby Atmos surround sound formats for it to work with spatial audio. "

 

[bigshot]

The DAC in AirPods only supports two codecs... SBC and AAC. It's BLUETOOTH, not Airplay (which is WIFI).

They aren't shoving 5.1 discrete with Atmos metadata across bluetooth to a little white peanut that goes in your ear and processing it there. They're sending two channel AAC with all of the hokus-pokus signal processing baked into it. That signal processing is probably done at the Apple Music Store and the AirPods internal processing consists of using the internal gyro data to calculate and process the head tracking. I've figured out some of what that is doing. It's more than just potting the sound back and forth. But I won't waste my time trying to talk about it here.

 

[Davesrose]

"Also important to note is that media content must be available in the 5.1, 7.1 or Dolby Atmos surround sound formats for it to work with spatial audio. "

Depending on standards, Dolby Atmos can be encapsulated in different sound formats (including ALAC).

Apple Music announces Spatial Audio with Dolby Atmos; will bring Lossless Audio to entire catalog

Frequently asked questions

Listen to Dolby Atmos music on iPhone

 

[Elegiac]

All those moments will be lost in time, like tears in rain

Will I dream?

#GreatRobotsOfHistory

 

[bigshot]

AirPods Max doesn't support ALAC or lossless. It has to be transcoded to AAC to be played on AirPods. The iPhone will sense that you are using AirPods and transcode on the fly.

Blu-rays use something like lossless Dolby True HD Atmos. That's the real home version of Atmos. The Apple TV uses multichannel lossy Dolby Atmos or AAC multichannel like in m4v movie files. (It doesn't support any DTS formats.) AirPods use AAC 2 channel with Dolby signal processing baked in for Spatial Audio, and they headset itself does some further processing. Apple uses the term "Spatial Audio" to describe any form of dimensional sound, regardless if the file is lossy or lossless, discrete or matrixed, or multichannel or two channel... It's all called "Spatial Audio". Dolby Atmos is the brand name associated with this vague terminology.