The sound of Wreckfest 2 - Dev Blog #03

Welcome to another edition of Wreckfest 2 Dev Blog. This time around we look at some of the audio upgrades and improvements in the game and related to car sounds. 

As you may recall from the previous design articles about careers, the term "alternative motorsports" got mentioned a lot. This sets much of the tone and direction also for audio designs. 

What this means is, every bit of audio in the game to come across authentic and support the immersion of 'being there'. Whether you are racing to win or enjoying a day out at the races to spectate the competition, the sounds you hear should support both experiences and adjust dynamically to meet the needs of momentary gameplay situations. 

A lot of what we need to build up the authenticity starts with the cars. To that end we've gone to the lengths of having some proper vehicles recorded, ones that are true the sports. It's not uncommon for these grassroots racing builds to run engine swaps and other mods. For that they sound unlike any daily drivers you'd see on the streets. 

Just rest your eyes on some of these beauties: [carousel autoadvance="true"][/carousel]

Such cars establish the foundation for Wreckfest 2 to have a unique sonic imprint against other car games. 

From sourcing to session arrangements to rigging to driving, recording cars all proper requires an experienced team and a lot of equipment. For that we've chosen to outsource the whole chunk of this work with partners in Europe and the US. 

For one road recording session example, here's a video of the source car for Bravion. It's shot by one of the recording engineers, standing at a trackside station to capture exterior angles for passbys etc. Video also shows the nice countryside location and some of the station mic setups. 

What little spec we have for this car, it's a BMW E39 with a 2.5 -litre I6 engine. Car is built for ice-racing; take note of that cool snowplough bumper mod! 

Then, for an example of a dyno recording, here's a 1965 El Camino all rigged up for the session, pulling a rpm ramp. You can see some of the recording setup, with exhaust mics placed over various distances. 

Early into the video there's also one physics-related detail demonstration: Prior to starting the actual rpm ramp portion of the dyno pull, the engine is first brought into lowest stable rpm at neutral load, after which the engine load increase gets swept in. This is a great example of how much the change in load can affect the exhaust sound character on V8 engines. 

The engine on this car is a swap; a 6.2-liter General Motors LS3 small-block V8, with upgraded throttle body, camshaft and forged pistons & rods. 3-inch Borla exhausts seal the deal. The source car itself is run to compete in autocross and similar track races. This LS3 is the source for our in-game car Rocket. 

Overall direction we have with car engine sound upgrades is to greatly improve dynamic response and bring sonic similarity on-par between the recorded and in-game cars. To that end we are incorporating a lot of the modern bells & whistles, like new audio synthesis techniques, cockpit reverberation models and sound layering. 

All this combined helps us to raise the overall sound quality and introduce additional, dynamic textures to increase immersion. Say for example, if you install a turbocharger, we can then dynamically add that sound layer on top of the basic sound model of the engine block. 

Compared to Wreckfest 1, we are also greatly increasing positional and directional sound of various parts that a car has. Say, depending on where the engine block or end of exhaust pipe are on the car, sounds of both will play from a correct location on the car. Move or chop off the exhaust pipe and the location of sound gets repositioned along.  

Here's a video of these object -based sounds in action: 

Whereas Wreckfest 1 had a static audio mix, we now have it fully dynamic between all sound sources of a car, based on which camera view or angle is active. Directionality of sound means f.ex. that, if you're looking at the car from opposite side to the exhaust pipe, its sound will be slightly muffled for the end of pipe being out of sight. 

But don't just take all this technobabble for an improvement: For a solid comparison of how much we can one-up sound quality with all this new tech, check out the video below. Here we have the same exact source recording of a truck diesel engine but implemented in both Wreckfest games with what tech each has. 

Quite the difference isn't it?! 

Driving a car would be nothing without wheel sounds. They are your "feet on the ground" and for that, the most important audio feedback you can have to a physics-based car game. To improve this area of car sounds, we've upgraded the player car to have sounds per wheel and created entirely dynamic sound models. 

When all the wheels have their own sounds, it means that each can react individually to these parameters, to sit on alternate surface materials etc. When in cockpit view, you also unlock detail like surround panning, with each wheel playing from the appropriate direction. 

Each wheel responds to the bristle -based tire contact physics simulation running at 360 fps, over six key parameters: 

• Surface material of tire contact (or loss of contact) 

• Lateral slip of tire contact 

• Longitudinal slip of tire contact 

• Weight load on the wheel 

• Wheel linear velocity 

• Wheel angular velocity 

The dynamic sound models we have are of this generic design. Here, the same model will work across all axle positions and drive configurations any car may have. Physics response allows for dynamic response based on car configuration. For example, the less power a car has, the less longitudinal slip there is, and thus tires will have less of launch slip screech on asphalt. Tires can screech also when a stationary car is pushed sideways or is sliding on locked wheels, etc. 

Here's an example video of Roadslayer and asphalt tire contact, with all assists disabled (for more slip!). Video also shows some of the physics simulation readouts. Take note how the sound changes whether an individual wheel is on the inside or outside of a turn, with weight load changing accordingly. 

Big part of how we experience sounds of cars in real life, it has more to do with the environment the car is in, rather than just the car itself. For a sneak peek, let's look at a few key features that we are building into our work-in-progress track editor tool, to introduce environment to the game. 

What 'environment' means in terms of audio, it covers both the passive and active sound sources. Passive sound ties to physical qualities of the surroundings, like structures and materials in a specific location, all which contribute to effects like certain reverberation characteristics. These are what the (active) sounds of a car will react with. We can refer to all these passive sound details simply as 'spatial audio'. 

Having the said reverberation, anything typical to a specific location across a racetrack, is the most important detail of spatial audio for us. Think of narrow passages (f.ex. tunnels or canyons), building interiors or bridge underpasses. These all are great examples of localized reverberation. Being able to define these into each track will greatly enhance feel of game environment; the immersion and authenticity to it. 

Here is a video that shows the setup of a reverb zone object, and the work-in-progress tooling in our editor. 

Come global launch, we will also offer a selection of reverb models for you to assign while building a modded track. 

Second important detail is to have active spatial audio of any environment, any ambience born of a specific location. Say, if you're driving on a forest road, you would no doubt hear sounds like birds chirping and the trees rustling in the wind. 

To support such groups of sound, we have a ambient audio component that can be added to game objects when needed. Here's a snapshot of the object attached to a crane. 

Third, when you have track-specific sounds like mentioned above, you also need a place to store the audio assets to. This is a feature that is missing from Wreckfest 1, but one we're now adding: An editor component to store soundbank references with a track. This allows to load customized soundsets with your modded tracks, instead of being limited just to what turnkey offerings (biomes, machinery etc.) we may ship with the game. 

That's about it for now, the overview of some of what we have cooking on the audio side of things. 

But what do you think? Does our Bravion feel like a worthy in-game version of the E39 that was recorded? Did the diesel engine feel like a worthy upgrade? Some other audio detail here that raised questions? 

If you have any specific WF2 dev topic you'd like to hear about in this blog, please don't hesitate to leave a request in the comments section.  

Thank you for reading through, we hope you found this interesting and until next time. 

Ta ta!