PlayStation lead system architect, Mark Cerny has explained how the upcoming Dolby Atmos feature works on the PS5. If you missed it, Sony is currently beta-testing a new PS5 system software which includes Dolby Atmos support for surround sound systems (and other things such as 8TB SSD support). However, since the beta went live, users have raised questions over how the tech works and how Sony aims to convert its current 3D Tempest feature into Dolby Atmos containers.
Cerny’s statement regarding Dolby Atmos on the PS5 was actually brought on after a video by Digital Foundry was posted on YouTube where the members of the team discussed the tech and incorrectly speculated how it worked.
The biggest thing to take away from this Dolby Atmos support on the PS5 is that it provides lag-free sound. On the Xbox and PC, Dolby Atmos is almost unusable at times due to the sound lag when enabled. For example, when you shoot a gun in Gears 5, theres a 500ms lag between seeing the shot and hearing the gunfire.
In a statement posted on Eurogamer, Cerny explains in depth how Dolby Atmos works and how Sony has taken the existing audio and automatically converted it to Dolby Atmos. Essentially, all games with 7.1 and 5,1 surround sound will make use of the Dolby Atmos container as the sound will go through the Tempest Engine and that would render the game sound into the channels on the system.
Cerny says that game sound already had 36 Ambisonic channels. These channels include direction where sound came from – including overhead sounds. That’s because developers already code their games to include this information even before thinking about Dolby Atmos. So when a game sends these 36 Ambisonic channels to the Tempest Engine going forward, it will know that overhead channels go to overhead speakers.
Of course, Cerny states that going forward, we can expect games to fully embrace Dolby Atmos even more as devs create experiences tailored for the 7.1.4 speaker setup. At launch of the software, the Tempest Engine will simply channel the overhead sound to the correct overhead speaker but Cerny claims sound designers can verify the highest quality of audio and emphasis these sounds in the future.
You can read the entire statement below. I simply broke it down above to make things easier and quicker to read.
It’s probably easiest to talk about Tempest-based 3D Audio and the Dolby device support in terms of Ambisonic audio, which is increasingly popular these days (note there are other strategies for 3D Audio, including ones that use discrete 3D audio objects, but situation is rather similar).
Ambisonic audio can be viewed as a pretty radical extension of stereo audio. With stereo audio, the game’s audio engine (or the middleware being used) will add a sound source into one or both channels based on its location – if the source is to the right of the listener it’s primarily added into the right channel, and so on. With Ambisonic audio, there are a lot more channels – fifth order is very common and uses 36 channels, so it allows pretty good locality to the audio. A sound source is then added into those 36 channels based on location; the math is a bit more complex than when using stereo but not overwhelmingly so. Because the audio processing is channel based (albeit at 36 channels rather than 2 channels), the audio designer keeps very good control of mixing, filters, etc., and strategies like dynamic range compression (where audibility of certain important audio such as player character voice is ensured) can be used as usual.
The Ambisonic audio channels are then handed off to the Tempest 3D AudioTech engine for rendering, which is to say that the Tempest engine uses the player’s HRTF and the speaker locations to create an appropriate audio stream for each speaker. The Ambisonic audio channels encode all directions, including above the player; even if rendering for headphones, this is very important, because it allows a sound “above” the player to be processed in such a way to sound as if it is truly coming from above – this is of course where the HRTF with its encoding of head and ear shape comes in.
Up until the most recent update, the Tempest engine would render the information in the Ambisonic channels into headphones, stereo TV speakers, and 5.1 and 7.1 audio setups. Now 7.1.4 has been introduced, with its four overhead speakers, but really nothing changes in the overall Tempest rendering strategy – the 36 Ambisonic channels already include audio coming from all directions, including above the player. To put that differently, the support of the four overhead speakers is “first class” support, they are handled just like any other speakers. Also note the rendering latency for these new speaker setups is identical to what it has been in the past for stereo, 5.1 and 7.1.
As a result, the 7.1.4 experience for existing games should be quite good. It is true that the game teams could not test with these speaker setups but support should be pretty automatic, the necessary game audio data is already there in Ambisonic form. Going forward, there’s an opportunity for improvement as the sound designers can verify the highest quality of audio on 7.1.4 speaker setups as well.