game audio
DESCRIPTION
Game Audio. Mark Peskir November 14, 2005 ITCS 5010. Overview. Terms/Fundamentals Computers and Sound Parameters, Filters, Effects Types of Sound Production Planning For Game Audio. Definitions. Sound: compression waves transmitted through a medium - PowerPoint PPT PresentationTRANSCRIPT
Game Audio
Mark PeskirNovember 14, 2005
ITCS 5010
Overview
• Terms/Fundamentals• Computers and Sound• Parameters, Filters, Effects• Types of Sound Production• Planning For Game Audio
DefinitionsSound: compression waves
transmitted through a mediumWave: cycle of compression and
rarefactionAmplitude: measure of sound wave
pressure
Coming soon: cool stuffComing soon: cool stuff
DefinitionsFrequency: speed of wave oscillation
Measured in Hertz (Hz)Pitch: a particular constant frequencyHertz (Hz): number of oscillations per
seconddecibels (dB): measure of the degree
of amplitudeNote: a predefined pitch used in music
Common Frequency Ranges
Human Hearing: 20Hz – 20kHzHuman Voice: 90 – 300 HzMiddle C: 261 Hz
Digital SoundA “unit” of digital sound is called a
sampleThe sampling rate is the number of
samples taken per secondBit depth: size of sound sample data
See Figure 5.5.2, pg 598
Nyquist LimitA sampling rate can only accurately
record sounds of frequencies at half its value
48 kHz sampling rate: can record a 24 kHz max frequency
That’s really high, so who cares?!That’s really high, so who cares?!
Common Sampling Rates“CD Audio” quality: 16 bit, 44.1 kIP Voice Chat (BattleCom, TeamSpeak):8 – 16 bit, 16k – 24k sample rateBurger King drive-thru: ???High-End sound cards support: 24/96, 24/192The Tradeoff: Performance vs. QualityThe Tradeoff: Performance vs. Quality
Flow of Tone Production• Tone is generated• Amplitude (volume)
set• Filters, effects, etc.
added• Sound is mixed with
other sounds• Sound signal sent to
speakers
Sound FormatsSample: short recording of live sound,
with frequency adjusted to produce other pitches/notes
Streaming Audio: a full soundtrack or complete sound effect, loaded into a buffer and played while the rest of sound loads
MechWarrior 2: used hybrid CD for MechWarrior 2: used hybrid CD for music!music!
Audio Compression• The Goal: reduce the amount of
data needed to produce quality sound (like JPEG images)
Two methods:• Bit reduction: reduce bit depth• Psychoacoustic Compression:
discard audio not generally heard (MP3)
ADSR EnvelopeAttack, Decay, Sustain, ReleaseCould define a variety of sound aspects(pitch, volume, rate of repetition)What would the envelopes look like for:What would the envelopes look like for:• Revving a car engineRevving a car engine• Cymbal crashCymbal crash• John Williams choirJohn Williams choir
Other Sound ParametersPan: the “left/right” location of the soundVolume: ratio of amplitude playedPitch/Frequency: can be assigned to
override a sound’s actual pitch3DGS:sound mySound = <gosh.wav>;snd_tune(mySound, 50, 100, -100);play mySound at 50% vol, 100% freq, leftplay mySound at 50% vol, 100% freq, left
Pass FiltersLow Pass Filter: only allow sounds
below a certain frequencyHigh Pass Filter: only allow sounds
above a certain frequencyBand Pass Filter: only allow sounds
in a given frequency rangeused for cutting “highs” and/or
“lows”
3D Sound MethodsHead Relative Transfer Function (HRTF)• used in stereo speaker config• dynamically changes balance for L/R• reduces high frequencies if behindToday: Dolby Surround Sound – 5.1, 6.1, 7.2!
Environmental EffectsEcho: early reflectionsReverberation (reverb): late reflectionsDiffusion: the “breaking up” of a sound
reflecting off of a rough surface (carpet)Obstruction: the blocking of a sound’s
direct path to the earOcclusion: high freqs being blocked by a
material, while low freqs pass through(car bass with windows up, underwater)
Environmental EffectsTwo current standards:• I3DL2: established by the Interactive
Audio Special Interest Group (IASIG)• EAX: created by Creative Labs for
SoundBlaster audio cards – multiple versions exist (1.0, 2.0, 3.0)
Difference in sound: ???Difference in sound: ???
Half Life 2: Soundscape DSP
Audio SystemsMIDI: Musical Instrument Digital Interface• file contains sound “instructions”• metaphor: sheet music for a computer• uses preloaded sound banksDigital Audio: actual recording• generally much better sound quality• more “real”• downside: much bigger file sizes
Audio SystemsMIDI:
Digital Audio:
Advanced Audio Programming
• Programmers should not have to Programmers should not have to deal with audio!deal with audio!
• Audio scripts handle production of sound (HL2 DSP presets)
• Common problems: sound variation, repetition, looping, ambience
Advanced Music Programming
• HALO 2: Quantum Audio – music has starts, ends, middles, transitions
• Interactive Music: “musical boxcars”
Voice InteractionPhoneme: individual voice soundLip Synching: matching phonemes to
mouth animationVoice Playback: generating words
using phonemesVoice Recognition: decoding voice
input to understood text of some kind
Dragon Naturally SpeakingDragon Naturally Speaking
Half Life 2: Phoneme Extractor
When you’re Project Lead:• Create an audio development
processPre-production: Production:audio engine SFX workflowgame style Music workflowfile system VO workflow
Foley workflow
When you’re Project Lead:• Create an audio asset list“How many sounds can this make?”“How often will we hear this?”“How much music can/should we
use?”• Excel spreadsheets are commonly
used
When you’re Project Lead:• Understand audio budget needs
•Audio Designer•Audio engineers•Composer•Voice actors•Recording equipment•Audio software•Audio hardware•Music gear
•Licenses (sounds, middleware)•Field Recording •Hired musicians•Music composition•Canned music, SFX, foley•SFX research•Sound processors•Sound file storage
When you’re Project Lead:• Integrate your audio team• Audio team works with art• Audio team works with animation• Audio team works with design• Audio team works with story writers
In short: COMMUNICATE!In short: COMMUNICATE!
The EndThanks for listening