Introduction to Audio Post-Processing Ivan Lee, Jun. 2005

2 Outline Overview Dolby Pro Logic II Dolby Virtual Speaker BBE & BBE ViVA SRS WOW & TruSurround XT (TBD) Q & A

3 Overview Tech. Comp. 2 channel Enhancement 2–to-multi ch. Matrix Decode Multi-to-2 ch. Virtual Surround Proprietary Sound Dolby Pro Logic II, Bass Management Virtual Speaker Headphone SRSWOWCircle Surround IITruSurround XT BBEBBE, ViVA RealtekEQ,Bass,Treble Collection of the APP Technology

4 Overview - Dolby Dolby Pro Logic II Sophisticated, matrix decoding technology that expands any two-channel source audio, such as CDs and stereo-encoded videocassettes, video games and TV broadcasts, to a five-channel full bandwidth (range) playback (Left/Center/Right/Left surround/Right surround), resulting in a surround experience. Dolby Virtual Speaker Highly advanced signal processing technology that delivers 5.1-channel surround sound from just two speakers. It's ideal for PCs and spaces where a full 5.1 home theater is not practical.

5 Overview - Dolby Dolby Headphone Revolutionary signal processing technology that delivers 5.1- channel surround sound over any pair of headphones for a richer, more spacious and less fatiguing listening experience.

6 Overview - BBE BBE HD Sound Natural Musical Realism Speech intelligibility Truly lifelike movie experience Improves simulated “surround” effects BBE Mach3Bass Extends the bass response BBE ViVA Integrates a 3D enhancement effect with BBE HD Sound BBE MP Integrates BBE with MP harmonic and restoration.For MP3 and all lossy audio compressions

7 Overview - SRS SRS The SRS® (Sound Retrieval System) 3D Stereo system is designed to retrieve and restore spatial information, directional cues, and other sonic nuances which are either missing or altered by the electronic reproduction of stereo and/or the microphone mixing process. SRS WOW FOCUS : Clarity Improvement TruBass : Bass Enhancement SRS : 3D-Audio

8 Overview - SRS SRS TruSurround SRS TruSurround delivers a compelling, virtual surround sound experience through any two- speaker, including internal television speakers and headphones. SRS TruSurround XT SRS TruSurround SRS Dialog Clarity Enhancement TruBass WOW

9 Dolby Pro Logic II Pro Logic II matrix decoder receives 2 channels and delivers feeds for three, four or more loudspeakers. To express Lt and Rt in terms of the intended direction of a source,independent of the magnitude. To express Lt and Rt in terms of the intended direction of a source,independent of the magnitude.

10 Dolby Pro Logic II Source Analysis L t 2 + R t 2 = 1 L t (α) = cos((α – 90)/2), R t (α) = sin((α – 90)/2)

11 Dolby Pro Logic II

12 Dolby Pro Logic II

13 Dolby Pro Logic II

14 Dolby Pro Logic II

15 Dolby Pro Logic II ParameterMovieMusicVirtualProLogicMatrix Surround delay10 – 25ms0 –15msNo10 – 25ms0 – 15ms Surround filterNoShelfNo7 kHz LPFShelf Surround coherenceOnOff OnOff Panorama controlOffOpt.Off Dimension controlOffOpt.Off Center-Width controlOffOpt.Off Auto-BalanceOnOffOn Off

16 Dolby Virtual Speaker Crosstalk Cancellation Listening Zone Sonic Signatures

17 Dolby Virtual Speaker

18 Dolby Virtual Speaker

19 Dolby Virtual Speaker Reference Mode Wide Mode

20 BBE & BBE ViVA The state variable filter has several advantages of biquads as a synthesizer filter. Lowpass, highpass, bandpass, and band reject are available simultaneously. Also, frequency and Q control are independent and their values calculated easily. f = 2 ‧ sin(PI ‧ Fc/Fs), q = 1/Q

21 BBE & BBE ViVA Block Diagram of BBE

22 BBE & BBE ViVA 3D Stereo of BBE ViVA

23 BBE & BBE ViVA Compressor / AGC in BBE ViVA

24 BBE & BBE ViVA Block Diagram of BBE ViVA

25 SRS WOW & TruSurround XT (TBD)

26 Q & A