2.3) Changing Properties
If an Object or Container is selected, the Sound SFX Property Editor view to the right displays settings that affect how the sound file contained within the selected Object will play. There are numerous Properties available depending on which Object or Container is selected. You will learn about some of them intuitively or through trial and error, but let’s discuss the most common and important ones before diving into the details.
First of select the dog Random Container.
As you can see to the right, there are the two most important Properties for any Object or Container, the Volume Fader and the Pitch Property. This is very convenient for the Technical Sound Designer because usually in Audio production tools, the pitch control is not prominently displayed even though you use it regularly. This is especially the case in Game Audio where pitch adjustment is constantly used, oftentimes to create the illusion of having an abundance of different sounds using only a single sound played at varying pitches.
Play back the dog Random Container a couple of times, and adjust the Volume Fader.
If the Volume Fader says 0, it means 0dBFS. This means that the sound files are being played back at exactly the level they have been exported in a Digital Audio Workstation by the Sound Designer. You don’t need to be a rocket scientist to find out that if you increase the level above 0dBFS then the sound gets louder. If you decrease the level to a negative value then the sound gets quieter. You can watch the meter to the right as it always displays the current level in dBFS the sound is being played back in. (Pic01 Volume Fader)
Play back the dog Random Container a couple of times and adjust the Pitch Property.
The Pitch Property value is expressed as musical cents. On a piano, there is 100 cents of pitch change between any two keys that are side by side, whether they’re black or white keys. The Pitch Property default value is 0, meaning that the Audio associated with the Object will play back at its original pitch. If you change it to for example -1200 cents, it means that the Object will play back one musical octave below the original pitch. Also notice that as the sound gets deeper in pitch, the playback speed is getting slower and the length of the sound clip is getting longer. This process is called Resampling. (Pic02 Pitch Property)
Now, play back the dog Random Container a couple of times and adjust the Filter Property.
There are two Filter Options, a Low- and High- Pass Filter for the sound. The value range is from 0 to 100, with each step having another cut-off frequency. (Pic03 Filters) It is not necessary to get more technical yet, just listen to how the sound changes as you apply a Filter. Let’s say the sound assets from the Sound Designer are a bit off frequency-wise, you as a Technical Sound Designer could apply some basic filtering to fix it or just you use those Filters in your creative process. You will do this in a later lesson.
With the basics covered, play back the level01 Blend Container and listen to the Atmo sounds all together.
As you might notice, the Atmo is very loud in the beginning. The reason for this is that the Blend Container plays back all Containers within at the same time. The second thing you might notice is, that after a couple of seconds the playback stops altogether. Now, let’s imagine that the Platformer Game fires an Event with a Play Action of this Blend Container in the beginning of the level and the sound stops after just a few seconds. Needless to say, there is an obvious problem with the Sound Design. You can change this using Looping and Crossfading Properties in the Play Type and Play Mode Section in the Property Editor for Random Containers. (Pic04 Play Type + Play Mode)
Depending on your screen size you will have to change the window size of the Property Editor in order to see all Properties of the selected Object or Container.
Look at the Play Type. It is very self-explanatory.
The Play Type dictates how the Random Container selects sounds within. You can choose between Random and Sequence Playback. In Wwise, Random can mean either a Standard Random selection, where each Object within the Container has an equal chance of being selected for playback, or a Shuffle Random selection, where Objects are removed from the selection pool after they have been played. You can leave Standard Random for now. To avoid that one Object is being selected twice in a row, there is a convenient option to avoid repeating last played element. Choose a value to your liking. This value is dependent on the Scope of your Object. With a Global Scope you can avoid repetition globally, if you play back the Object a couple of times simultaneously on different Game Objects within your game. With a Game Object Scope you can avoid repetition per every single Game Object within your game. (Pic05 Avoid Repeat and Scope)
Now look at the Play Mode.
The Play Mode dictates if the Random Container should play one random sound per Step, which means one sound for every Play Action, or if the playback should be Continuous. A single sound per Play Action is okay for the Robot because a new Event with a Play Action is triggering a new sound at the start of every animation cycle, but for the dog you want it to not only bark once but rather in a Loop as long as the Atmo is being played back. Therefore you can choose Continuous, Loop and Infinite. Any specific Number of Loops is possible, but in this case Infinite playback is the right choice. You want the dog Random Container only to stop if a dedicated Event with a Stop Action is being called by the game engine, for example at the end of the level as the Player Character transitions to the next level. (Pic06 Loop Playback)
Listen to the Random Container.
You have now created a loop, but the playback doesn’t sound right. The dig is now barking constantly back to back which could start to annoy a players very quickly. There is a neat trick to create random silence in between different dog barks with different weighting.
Create an empty Sound SFX Object within the dog Random Container.
It is highlighted in red, since there is no sound associated with the Object. You can see the silence Object in the Contents Editor to the right. (Pic07 Silence Object)
Click on the empty silence Object and choose Add Source >> in the Contents Editor. Choose Wwise Silence.
Now the silence Sound SFX Object is colored in white, which means it has an Audio Source. This time the Audio Source is not an sound file but rather silence. (Pic08 Wwise Silence) You can choose the Duration of the silence in seconds, such as a Random Minimum and a Random Maximum. The later two are offsets from the Duration value and they define the minimum or maximum possible length of the silence. (Pic09 Silence Randomisation) This is very convenient, because you can create silence in between dog barks, that has a random length within a defined range each time a silence Object is being selected by the Random Container.
Select the dog Random Container one last time and look at the Contents Editor.
You can also assign a Weight value to each of the Objects within a Random Container. The weight value can increase or decrease the likelihood that an Object is selected for playback. The Weight value set for a particular Object is relative to the sum of all Weights in the Container. This basically means that the number assigned for each Object represents the number of chances the Object will be selected for playback out of the summed total. For example, if there are two Objects in the Container with Weight values of 1 and 100, the first Object will have a 1/101 chance of being played and the second Object will have a 100/101 chance of being played. Let’s increase the Weight for the silence Objects to reduce the dog barking within our looped Random Container. (Pic10 Weighting).
For the last Property you are going to work with, select the wind Container and listen to the wind sound.
After a few seconds the sound stops. You now know what to do. Choose the right Play Type and set the Play Mode to Continuous. Listen to the wind sound. It now plays back a newly picked sound file back to back. The only problem is the transition. There is a small noticeable click in between two sound files, because the waveforms don’t perfectly match. To make it sound professional click the checkbox for Transitions, choose a logarithmic Crossfade or Xfade (power) as it is called by Wwise and set a length for the Crossfade between the current and next sound file being picked. (Pic11 Transitions).
There are many different Transition Types, all with different use cases. The Xfade (amp) and Xfade (power) are very similar, they both perform a Crossfade. It really depends on the kind of Audio material you want to crossfade which one sounds best, but for Transitions from one sound file to a similar sounding one the logarithmic Crossfade or Xfade (power) Crossfade sounds best.