Halo: Combat Evolved, the first release of the now renowned Halo series, came out in November 2001 as a launch title to accompany the release of the Xbox console and as a showcase of the platforms capabilities. This new console saw major developments in sound capability and was the first to allow for Dolby Surround during game play, not just for pre-prepared cinematic sections. To assist in my analysis of this title, I will at times make reference to the insights provided by the game’s composer Martin O’Donnell in his Gamasutra entry on the project.
It becomes clear, from reading O’Donnell’s article, that the sound team were well aware of the direct completion between video games and other visual arts in the media climate of the time. It is also evident that they knew the surround sound capabilities of the Xbox would allow them to engage in this struggle head-on, in terms of the audio. Overall their aim was to create a soundtrack that could rival a Hollywood blockbuster, but that was both realistic and immersive for the end user.
O‘Donnell mentions how he went about implementing a sense of continuity in the menu and opening cinematic sequences of the game and says he prefers “a consistent audio experience where sound or music isn’t abruptly cut off when the user makes a menu choice, where there can be a sense of elegance and continuity between the opening movie, interface and loading screen.” - But I would say that this game goes beyond that and continues this cinematic and immersive experience into the game itself, providing a fully encapsulating game play environment.
The implementation of this non-repetitive soundscape is taken care of by the game’s audio engine. The game’s sound library is made up of a range of different sound files for each audio event, that are relevant to certain environmental and physical conditions. The playing of this sound files and how they are played, is then organised by a system of sound-tags. The method by which these are recalled can be summarised thus:
- An in game action calls for a sound event to happen, in the form of a sound tag.
- The audio engine, upon receiving the sound-tag request, then takes into account player state, environmental factors, time since last sound occurrence, etc, to then call up an appropriate sound file.
- All of which takes place within a fraction of a second.
The sound-tag may also result in multiple sound files being called up and played back; for example an environmental soundscape may be made up of several layered sounds.
One of the most detectable ways in which this system is used is though the dialogue of the NPCs within the game. As the in-game dialogue is made up of many short fragments of speech, these can be combined in almost infinite combinations. O’Donnell notes “there are more than six thousand lines of dialogue in the game and one of the elements I still find enjoyable is listening to new and unique combinations of real-time interaction between the marine and alien AI’s. I literally never know what they’re going to say next.” However, although the bank of available dialogue is vast, the recall is very controlled and systematically organised. This is done with a complex web of situations where dialogue is needed: 12 main categories than split down into multiple smaller categories, each of which has several permutations of speech that would be relevant. “For example, in the category ‘hurting people’ one of 4 main sound-tags, ‘damaged enemy’ contains between 15 to 20 permutations depending on the character.” This means that if the end user happens to repeat a situation or scenario within the game, the dialogue has the scope to vary every time.
Similarly the sound effects are designed to vary. In creating overall ambience for the different settings within the game, as well as the continuous sounds (such as wind) one-shot sounds are used, that can be randomised in terms of surround sound position, repeating interval, volume and pitch, all with specified parameters. Other sounds, whose playback is directly triggered by the player, were designed like the dialogue to call up and play from a range of permutations. However, it is more evident that these sounds are aware of player state: “the automatic rifle sound-tag is a collection of gunfire sound file permutations that are called in sync with the weapons rate of fire. Each call is interrupted by the subsequent call until the trigger is released and then the permutation is allowed to finish playing.” This also helps to stop the audio environment becoming cluttered with sounds. Other examples of how the audio adapts include the pitch and volume variation of engine sounds in relation to factors relating to the current state of the vehicle.
The music playback is also linked to game play, albeit in a somewhat more basic way. The premise behind this system is that the playback of each musical cue consists of a ‘start’, a ‘loop’ and an ‘end’ section, the playback of which and transition between is controlled by what is happening on screen and a what stage a play is at in terms of mission progress and level position. A more detailed explanation of this can be found in the Producing Content section of O’Donnell’s article.
VIDEO EXAMPLE (at top)
The video example I have chosen to include, highlights a number of the issues addressed within the main body of analysis above. The example comes from the very beginning of the games narrative and thus is the first experience a player would have.
As the cinematic of the space ship crash ends, we smoothly transition into game play without any noticeable change to the audio track and are introduced to the ‘voice in your head’ that accompanies you throughout the game and guides you with objectives. As the player explores the area outside the ship this voice reacts to what is seen and incoming NPCs. In this scene, the waterfall provides an example of a sound that varies depending on character position. There are also a number of bird sounds that occur at random as the player walks around the environment; this adds to the realism by using a sound that the player would recognise and associate with the outdoors.
As well as the voice that is heard, the footsteps are another good example of where you can hear that a range of samples have been used and that they are called back at random. Contrastingly however, despite all the attention to detail and the clever implementation behind it, the machine gun sound does at times when the player is holding down the trigger, sound a little bit like a looped sound; although it is still clear that the audio engine is still working to cut all but the last sound short, until the sound would naturally die away.
In terms of music, there appears to be two main cues in this clip. The first being the tension music used as the ‘drop ships’ are seen and the second being the ominous drone that fades in after the last enemy is killed at the base over the hill.
As a means of contrast, this video shows a different players experience of the same level.
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