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Positional Audio and Window Highlighting for the Access Grid

Positional Audio and Window Highlighting for the Access Grid. Robert Putnam (putnam@bu.edu) Boston University Scientific Computing and Visualization. Agenda. The problem Prototype positional audio Prototype window highlighting Distribution/installation Discussion. Who's talking now?.

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Positional Audio and Window Highlighting for the Access Grid

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  1. Positional Audio and Window Highlighting for the Access Grid Robert Putnam (putnam@bu.edu) Boston University Scientific Computing and Visualization

  2. Agenda • The problem • Prototype positional audio • Prototype window highlighting • Distribution/installation • Discussion Boston University Scientific Computing and Visualization Group

  3. Who's talking now? • In some AG contexts, it is not always clear which video window contains the current speaker. The problem is exacerbated by: • Multiple, concurrent speakers • Users unfamiliar with the AG • Users unfamiliar with each other • Remedy: look for familiar face or moving lips. Boston University Scientific Computing and Visualization Group

  4. What’s that noise? • In some AG contexts, it is not always clear who is transmitting echo or noise. • Remedies: • Broadcast appeal • Operator mutes RAT streams one at a time until offender is found. Boston University Scientific Computing and Visualization Group

  5. Solution #1: Positional audio • Use location of site's video window(s) to determine its audio position in stereo field. Boston University Scientific Computing and Visualization Group

  6. Solution #1: Positional audio • Preliminary system design • Components • (Minimally modified) vic and RAT • “Agent” which communicates with vic and RAT • Sequence of events • Operator moves window • Agent gets report of window movement from vic • Agent sends audio panning command to RAT • Need: communications & audio localization layers. vic agent ? RAT ? ? Boston University Scientific Computing and Visualization Group

  7. Positional audio • RAT has built-in support for “3D audio”* • RAT’s localization methods: • Interaural Intensity Difference (IID) • Difference in sound intensity between near and far ear. • Interaural Time Difference (ITD) • Difference in time of arrival between near and far ear • Head Related Transfer Function (HRTF) • 3D-location-specific filtering effect of ears, head, and torso. • *Actually “1D,” since there’s only a single degree of freedom. Boston University Scientific Computing and Visualization Group

  8. Positional audio • Revised system design: • What about communications? Next slide… vic agent ? RAT 3D audio ? Boston University Scientific Computing and Visualization Group

  9. Message Bus • RAT’s control, user interface and engine already communicate via the Message Bus (“mbus*”): • So… rat-ui rat-engine mbus rat-control *see www.mbus.org Boston University Scientific Computing and Visualization Group

  10. Positional audio • Revised system design: • Next: what mbus message is used to enable 3D audio? vic agent RAT 3D audio mbus mbus Boston University Scientific Computing and Visualization Group

  11. 3D audio mbus message • 3D audio mode is enabled for a given RAT source via an audio.3d.user.settings message: audio.3d.user.settings rat-ui rat-engine tcl mbus Boston University Scientific Computing and Visualization Group *see www.mbus.org

  12. Talking to RAT • So, agent sends audio.3d.user.settings message to rat-engine: • ssrc = “Synchronization source” = RTCP stream id • azimuth = horizontal angular distance of listener from sound source. (90 = panned left; -90 = panned right; 0 = panned center) audio.3d.user.settings ssrc azimuth vic ? agent rat-engine mbus mbus Boston University Scientific Computing and Visualization Group

  13. Listening to vic • Next, create new mbus message • window.xy • Normalized xpos (0 – 1.0) • Normalized ypos (0 – 1.0) • Name of video window (e.g., “LANL(Video)”) • Whenever video window is moved, resized, or renamed, send window.xy message to agent. vic window.xy agent audio.3d.user.settings rat-engine mbus mbus Boston University Scientific Computing and Visualization Group

  14. Associating vic and RAT streams • Agent responsible for determining which video windows correspond to which RAT streams (ssrc’s): • As of AGtk 2.4, it is assumed that vic and RAT streams have the same name • I.e., RAT “LANL” corresponds to vic “LANL(Video)” vic window.xy agent rtp.source.name rat-engine “LANL(Video)” 04b6910a “LANL” Boston University Scientific Computing and Visualization Group

  15. Solution #2: Window highlighting • System shown at May 2003 AG retreat • Feature request: visual indication of current speaker • But, danger of distraction/fatigue (i.e. too much visual clutter or “flashing”). Boston University Scientific Computing and Visualization Group

  16. Window highlighting • Change border color of site’s video windows when its audio rises above a threshold. • Two new mbus messages: • RAT: rat.source.amplitude(source_id amplitude) • Report each stream’s peak amplitude 2-3X / second • vic: highlight.window(window_id on_off) window.xy audio.3d.user.settings vic agent rat-engine highlight.window rat.source.amplitude Boston University Scientific Computing and Visualization Group

  17. Window highlighting Boston University Scientific Computing and Visualization Group

  18. Window highlighting • Window stays highlighted during brief pauses in audio unless another site begins transmitting. • Each site’s local video windows also highlight when RAT transmitting (“On Air” alert). • Window border highlight color and width is configurable in AG service. Boston University Scientific Computing and Visualization Group

  19. Setting up the system • Install stereo speakers/amplifiers • Install stereo wiring to and from echo canceller (aka “the Gentner”): RAT pc line out l r Gentner amplifier l r l r l r Boston University Scientific Computing and Visualization Group

  20. Setting up the system • Create left+right echo cancellation reference: Boston University Scientific Computing and Visualization Group

  21. Setting up the system • Remove or disable original video consumer and audio services and add two new ones: • HighlightVideoConsumerService.zip • PositionalAudioService.zip Boston University Scientific Computing and Visualization Group

  22. Setting up the system • Configure HighlightVideoConsumerService: Venue Client Windows Desktop Boston University Scientific Computing and Visualization Group

  23. What next? • Ready for beta testers! Get it here: • http://scv.bu.edu/~putnam/ag-audio/services-2.4.zip • Zip file contains services for Windows / Linux, PIG / multi-computer configurations. • Request features / report bugs here: • putnam@bu.edu Boston University Scientific Computing and Visualization Group

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