Heard About: Battlefield 4

Sadly, there’s no shortage of real-life reference for a Battlefield title, courtesy of the world’s recent and ongoing conflicts. Visceral footage of the Arab Spring and Syrian situations flood news channels, YouTube and social media sites defining today’s sound of war.

Audio director Ben Minto says this can influence how his team approaches each title.

“At DICE, we’re constantly evolving source material, benchmarks, processes, techniques and ideas – only towards the last six months’ development do we really lock things down,” he says.

“Each release is like an audio snapshot of the time. Bad Company was war as recorded through a Handy Cam mic. Bad Company 2 was akin to mobile phone recordings uploaded to YouTube. For Battlefield 3, the ‘unedited war’ vibe of contemporary Iraq and Afghanistan documentaries was the benchmark, resulting in a more refined and decipherable soundscape for the game.

“For Battlefield 4, we wanted to recapture the rawness of BC2, but not at the expense of clarity and readability. And whilst your firearm is the key way you interact with the environment, you have a big part to play too, so we’ve taken player foley out of the High Dynamic Range mixing system. Now explosions will not cull your footsteps; there’s a constant sonic connection between character and world.

“We’ve also applied learning from Iron Sights/Zeroth Person implementation – so firing from the hip sounds different to firing down the sights – to the foley sounds. We’re repeatedly asking how can we bring sounds closer to the player, such as using subtle, neutral self-voice emotes from the ubiquitous ‘being shot’, to the G-force strains in-cockpit or breathing in water when in danger of drowning.

“We have extended our systems to deal with events near you, and then on you. The sound of a water sprinkler changes when you stand under it and get the ‘water on helmet sound’, making it personal. This is the ‘Go-Pro helmet-mounted camera’ take.”

MILITARY MIXERS

A recent innovation was achieved by extending the use of context-sensitive dynamic parameter controllers, dubbed ‘mixers’. ‘Context sensitive’ means it can be activated by almost anything: area triggers, scripting logic, number of bullets remaining, health, screen transitions, special events and so on. ‘Dynamic’ means they can vary depending on external controllers.

Many mixers can be concurrently active and, by applying a hierarchical dominance rule-set, summed together.
Minto continues: “A parameter is any value, not just the ‘amplitude’, ‘gain’ or ‘loudness’ of an individual asset/channel. It can be anything from frequency and pitch, to internally-defined parameters like Area Type (used for selecting gun tails), Storminess (explained below) or even a simple binary Indoor/Outdoor switcher.

“Mixing a storm is difficult within an interactive environment, and more so when you have an automated mixing system trying to help. You want your storm assets to punch through and ‘feel’ loud but this doesn’t necessarily mean ‘play’ loud. The storm is dynamic in both assets and implementation so a fixed solution would feel unnatural. Our ethos is let the sound come first and then figure how to drive everything from that.

“We took the output of the Storm Sampler Nodes – samplers being the wav container playback entities within Frostbite – into an LPF, then into a VU meter. This is equivalent to an envelope follower; from there the outputted VU level is slewed, clamped and scaled to give us a value between zero and one – this becomes the Storminess parameter, which gives a close approximation to the storm intensity.

“The Storminess parameter is then used to drive other parameters in many different context-sensitive mixers. For the Angry Sea section first shown at E3, the mixers running include a side-chain-like amplitude mixer: the storminess amplitude will reduce volume of buses prior to the HDR, like shouting into the wind, or in some cases give a volume bump.

“The visual swell of the ocean and tilt offset of the deck is controlled by a unique sound patch for the area, and in addition to this we combine the Storminess with the wind direction to further modify the player’s pitch and roll, which in turn, is very effective at selling the intensity of the storm effect.

“An additional feature includes a zero-ing of the effect when entering Iron Sights for accuracy, which delivers a tighter more compressed feel to the mix in a smaller, more chaotic window of dynamic range.

“The envelope follower is just one example of a new core system that enables a tighter synergy between cause and effect. Now, for example, the waveform of the explosion is the key driver for the aftershock visual shake and effect, whereas previously the only connection was initial timing and intention. Now there is an intensity and story-match between the disciplines, creating a more unified experience.”