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Game Audio

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

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Game Audio

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  1. Game Audio Mark Peskir November 14, 2005 ITCS 5010

  2. Overview • Terms/Fundamentals • Computers and Sound • Parameters, Filters, Effects • Types of Sound Production • Planning For Game Audio

  3. Definitions Sound: compression waves transmitted through a medium Wave: cycle of compression and rarefaction Amplitude: measure of sound wave pressure Coming soon: cool stuff

  4. Definitions Frequency: speed of wave oscillation Measured in Hertz (Hz) Pitch: a particular constant frequency Hertz (Hz): number of oscillations per second decibels (dB): measure of the degree of amplitude Note: a predefined pitch used in music

  5. Common Frequency Ranges Human Hearing: 20Hz – 20kHz Human Voice: 90 – 300 Hz Middle C: 261 Hz

  6. Digital Sound A “unit” of digital sound is called a sample The sampling rate is the number of samples taken per second Bit depth: size of sound sample data See Figure 5.5.2, pg 598

  7. Nyquist Limit A 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?!

  8. Common Sampling Rates “CD Audio” quality: 16 bit, 44.1 k IP Voice Chat (BattleCom, TeamSpeak): 8 – 16 bit, 16k – 24k sample rate Burger King drive-thru: ??? High-End sound cards support: 24/96, 24/192 The Tradeoff: Performance vs. Quality

  9. 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

  10. Sound Formats Sample: 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 music!

  11. 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)

  12. ADSR Envelope Attack, Decay, Sustain, Release Could define a variety of sound aspects (pitch, volume, rate of repetition) What would the envelopes look like for: • Revving a car engine • Cymbal crash • John Williams choir

  13. Other Sound Parameters Pan: the “left/right” location of the sound Volume: ratio of amplitude played Pitch/Frequency: can be assigned to override a sound’s actual pitch 3DGS: sound mySound = <gosh.wav>; snd_tune(mySound, 50, 100, -100); play mySound at 50% vol, 100% freq, left

  14. Pass Filters Low Pass Filter: only allow sounds below a certain frequency High Pass Filter: only allow sounds above a certain frequency Band Pass Filter: only allow sounds in a given frequency range used for cutting “highs” and/or “lows”

  15. 3D Sound Methods Head Relative Transfer Function (HRTF) • used in stereo speaker config • dynamically changes balance for L/R • reduces high frequencies if behind Today: Dolby Surround Sound – 5.1, 6.1, 7.2!

  16. Environmental Effects Echo: early reflections Reverberation (reverb): late reflections Diffusion: the “breaking up” of a sound reflecting off of a rough surface (carpet) Obstruction: the blocking of a sound’s direct path to the ear Occlusion: high freqs being blocked by a material, while low freqs pass through (car bass with windows up, underwater)

  17. Environmental Effects Two 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: ???

  18. Half Life 2: Soundscape DSP

  19. Audio Systems MIDI: Musical Instrument Digital Interface • file contains sound “instructions” • metaphor: sheet music for a computer • uses preloaded sound banks Digital Audio: actual recording • generally much better sound quality • more “real” • downside: much bigger file sizes

  20. Audio Systems MIDI: Digital Audio:

  21. Advanced Audio Programming • Programmers should not have to deal with audio! • Audio scripts handle production of sound (HL2 DSP presets) • Common problems: sound variation, repetition, looping, ambience

  22. Advanced Music Programming • HALO 2: Quantum Audio – music has starts, ends, middles, transitions • Interactive Music: “musical boxcars”

  23. Voice Interaction Phoneme: individual voice sound Lip Synching: matching phonemes to mouth animation Voice Playback: generating words using phonemes Voice Recognition: decoding voice input to understood text of some kind Dragon Naturally Speaking

  24. Half Life 2: Phoneme Extractor

  25. When you’re Project Lead: • Create an audio development process Pre-production: Production: audio engine SFX workflow game style Music workflow file system VO workflow Foley workflow

  26. 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

  27. 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

  28. 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!

  29. The End Thanks for listening

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