Multichannel Audio Technologies

Transcription

1 Multichannel Audio Technologies Dr. Gavin Kearney Room 23, Top Floor, Printing House What is multichannel audio? 1. A way of expanding and enriching the sound of audio playback 2. Recording additional sound channels that can be reproduced on additional speakers. (e.g. two and 3 channel stereo) 3. Most commonly used in SURROUND sound applications (e.g. 5.1, 7.1 surround sound) Where can we find it? 1. Cinema 2. Home entertainment 3. Video games 4. Live sound reinforcement 5. Audio Visual Installations 1

2 Why do we need it? 1. Enhancement and spatialisation of music! 2. Enhanced cinematic experience (Spatial effects) 3. Perception of Naturalness (Sound field reconstruction).. IMMERSION!!! Enhancement and spatialisation of music! - Surround sound allows us to set up new musical perspectives Audience View Enhancement and spatialisation of music! - Surround sound allows us to set up new musical perspectives Ensemble View 2

3 Enhancement and spatialisation of music! - It frees us to position and move audio for greater emotive effect more immersive music! Enhancement and spatialisation of music! - We can (with reasonable effect) superimpose one acoustic environment onto another Why do we need it? 1. Enhancement and spatialisation of music! 2. Enhanced cinematic experience (Spatial effects) 3. Naturalness (Sound field reconstruction) 3

4 Enhanced cinematic experience Enhanced cinematic experience - Usually consist of 5 channels (Front left, front centre, front right, rear left, rear right) and a Low Frequency Effects channel (LFE). Enhanced cinematic experience - Not designed for accurate full surround imaging, just good frontal imaging with rear sound effects. 4

5 Why do we need it? 1. Enhancement and spatialisation of music! 2. Enhanced cinematic experience (Spatial effects) 3. Naturalness (Sound field reconstruction) Naturalness - Good spatialisation can give the feeling that you re there! - Huge applications in music, gaming, 3-D cinema, teleconferencing, interactive installations - Involves sound field reconstruction! How do we create the spatialised audio? 1. Multichannel recording techniques! 2. Multichannel spatialisation techniques! 3. Loudspeaker Layouts 4. Codec choices 5

6 Recording Techniques? Spatialisation? Amplitude Based Systems e.g. VBAP Spatialisation? Soundfield Based: Ambisonics + + = 6

7 Spatialisation? Physical Based: Wave Field Synthesis 7

8 - Dolby Surround Pro Logic II - Dolby Surround Pro Logic II Discrete: Dolby Digital, DTS 8

9 - Dolby Surround Pro Logic II Discrete: Dolby Digital, DTS Dolby Pro Logic IIx, Dolby Digital EX, DTS ES - Dolby Surround Pro Logic II Discrete: Dolby Digital, DTS Dolby Pro Logic IIx, Dolby Digital EX, DTS ES Dolby Digital Plus, DTS-HD - Dolby Surround Pro Logic II Discrete: Dolby Digital, DTS Dolby Pro Logic IIx, Dolby Digital EX, DTS ES Dolby Digital Plus, DTS-HD - SDDS (Sony Dynamic Digital Sound) 9

10 Cinematic Solutions: : Twice as good as 5.1! - Actually has 14 discrete channels: Five front speakers: Five surround channels: Two LFE channels: LFE Left, LFE Right Two Height channels: Left Height, Right Height Cinematic Solutions: Ultra-High Definition (NHK Corp) Codecs? - Most commercial surround sound systems utilise specific audio codecs. 10

11 Conclusions - Multichannel audio is an effective medium for enhancement of music, cinema, and other auditory presentations. - The application and desired auditory effect determines the loudspeaker layout and decoding scheme. - The aims of this course are to aid the audio engineer/ spatial musician in determining which multichannel scheme works best for a given application and environment, and to motivate further innovation in multichannel audio technologies. Multi-channel Audio Technologies: 12, 2 Hour Lectures, 2 Assignments Course Outline Week 1: Introduction to Multichannel Audio Technology Week 2: Mixing for Discrete 5.1 Surround Sound Week 3: Mastering for Discrete 5.1 Surround Sound Week 4: Up-mixing and Down-mixing surround sound Week 5: Surround Sound Recording Techniques 1 Week 6: Surround Sound Recording Techniques 2. Week 7: Mixing Recorded surround Audio/ Surround Sound with Height Week 8: Introduction to Ambisonics Week 9: More about Ambisonics Week 10: Spatial Impulse Response Rendering Week 11: Binaural and Transaural Surround Sound Technology Week 12: The future of Multichannel Audio Extra Spatial Music Seminar before Christmas 11