Non - Repeating Ambiances Within Crysis
In this article i will look at several different sections of the game, concentrating on the non repeating nature of the ambiances. throughout the game there are many different levels, all of which offer a different ambience to set the scene and also make the gameplay more realistic.
A non-repetitive ambiance is basically many layers of sounds that are not playing as a loop. these sounds can be triggered by an aspect of the gameplay but in the cases i will be looking at the sounds are randomised.
creating ambiances in this way not only gives the game more 'realism' but also allows the sound designer to build an impressive ambiance using up less memory. in this diagram you can see a very simple representation of how the layers could be called for playback within the game. the background track would always be playing, this would be the low rumble heard in the first section of the video. this is most likely to be 1 looped sound, as it has no variation and simply serves the purpose of letting the player know they are outside.
The middle distance sounds depicted in the diagram could be those of the distant bird sounds in the first section of the video or those of the waves hitting the shore in the night time section. these sounds are no doubt repeated after a period of time, but the way in which they are randomised covers this fact up. In the case of the waves hitting the shore in the night clip, there could be 4 different small loops containing wave sounds. Only one of these loops can be playing at any time, but one has to be playing.
The close-up sounds; ie the birds, frogs and flies, will again be short clips that are triggered in a random manner. Each of the sounds plays back with a probability of 6.5% making the random feel of these sounds much greater than those of the middle ground. it is possible that within crysis it is not imperative that these sounds be playing all the time, so there could be a short randomised delay between the triggering of each sound.
This effect could be accomplished in the Unreal 3 Editor quite simply like this:
The ambiance within the Crysis examples no doubt has many more layers than i have shown in the example. Also with the addition of the OpenAL and EAX 5.0 software, the sound designers have been able to add real time effects to the sounds for greater variation. Effects include Pitch and Volume variation and also some filtering of certain frequencies.
One of the features of the suit worn by the character in the game is 'Cloak Mode', then the player enters the cloaked mode the sound is changed by filtering out all of the top end frequencies (4000Hz and above). This filtering of the sound gives the player a slightly more 'closed off' feeling really giveng the impression of being cloaked. Below i have cut out 2 sections of the audio from the video and have viewed them in the frequencies view in Adobe Audition. the top picture is Uncolaked and the bottom picture is Cloaked.
This effect adds another aspect to the variation of the sound in the game, as the player can cloak or uncloak at any time.