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FX Direct Audio System for V+

FX Direct Audio System for V+. What Is FXDirect ®. Audio Subsystem Add-on to V+ Currently built-in Consists of Objects for Manipulation of Audio Synthesis/sampling Mixing. What Is FXDirect ®. V+ Wrapper Around DirectSound ® Can be used with advanced hardware (SMx)

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FX Direct Audio System for V+

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  1. FXDirect Audio System for V+

  2. What Is FXDirect® • Audio Subsystem Add-on to V+ • Currently built-in • Consists of Objects for Manipulation of Audio • Synthesis/sampling • Mixing

  3. What Is FXDirect® • V+ Wrapper Around DirectSound® • Can be used with advanced hardware (SMx) • FXDirect alone – 4 channels (OTS sound Cards) • FXDirect with SMx – Up to 50 Channels

  4. Overview • Basic Sampling Theory • Evolution of Audio Generation • Sampling Versus Synthesis • Microsoft DirectX • FXDirect • Demo and Hands-On

  5. Basic Sampling Theory • “Sampling” is Digitizing Waveforms • Finite sample rate • Typical 22khz, up to 48khz

  6. Analog/Digital - Digital/Analog

  7. Bandwidth Issues • Nyquist Frequency • Maximum Usable Frequency is ½ Sample Rate • Assumes Ideal Conditions

  8. Bandwidth Issues • Higher Sample Rates • More samples (memory & processor overhead) • Higher quality • Lower Sample Rates • Less samples, lower quality of audio • Typical Industry • CD quality audio is 44.1khz • Telephone quality is 8khz.

  9. Sample Bit Depths • More Bits Per Sample • Higher Quality (Lower THD) • Typical Industry • CD quality 16 Bit • Telephone quality is 12 Bit • Up to 24 With Gadget Labs System

  10. Sample Rate vs. Control Rate Processing • Sample Rate • Processor Runs at Sample Rate • Processor Manipulates Samples • Very High Overhead • Control Rate • Processor Runs at 20 – 30Hz • Processor Manipulates Buffers of Samples • At 22kHz SR, Buffer Would be 733 Samples, 1 Sec.

  11. Sample Rate Processing • SimPhonics FX-30 System • Manipulate Individual Samples • DSP Iterates at Sample Rate

  12. Control Rate Processing • Much Lower Processing Rates • Typically 20 – 30Hz • Samples Are Stored As “Chunks” or Buffers

  13. Which Technique to Use? • Good Question • PC Technology Can’t Operate at SR • Very Inefficient • Dedicated DSP is Ideal for SRP • Big Bucks • Non Standard

  14. When to Use SRP • Mixing Low Latency Audio Input • Delays Using CRP are Unacceptable • Simulating Voice Systems (Intercoms, etc) • Super Special Stuff • ???

  15. New Technology and Standards Make CRP Work for Simulation • Before DirectX, No Standard Mixing API • Intel’s MMX Initiative • Intel and Microsoft Collaborate/Squabble • Microsoft Launches DirectX® • DirectSound is a Subset of DirectX

  16. DirectSound

  17. Sample Rate Conversion • Important DirectSound Feature • Different SR Secondary Buffers are Combined • DirectSound Does the SRC • Quality and Overhead User Configurable • Control Panel, Multimedia Icon

  18. Using FXDirect with DirectSound

  19. Dynamic Control of Sounds • Since DirectSound Performs SRC: • Frequency and Amplitude May be Controlled in Real-Time • Since Any Waveform Can Be Used: • CRP Can Be Used in Most Cases for SRP. • I.E. Sine Wave Can Be Synthesized Off-Line and Used as a Secondary Buffer FXDirect Object • Therefore, Don’t Let Them Tell You: • You can’t Use CRP for Simulation Systems

  20. Multiple Channels

  21. Practical Example

  22. FXDirect Operation • FXDirect can use Almost Any Sound Card • Direct Sound Driver for Best Performance • Full Duplex for Voice I/O • WDM Driver Desirable

  23. FXDirect Operation Platform Shell Configure Menu Associates FXDirect Channels with Audio Outputs

  24. Channels Versus Outputs • Multi-Channel Cards are VERY Rare • Most Do Not Use WDM Driver • Others Do Not Enumerate Channels Properly • As of Today, Only Two Exist • Gadget Labs With Stage Research and SimPhonics Drivers • Echo Corporation’s Layla System

  25. FXDirect Operation Stereo Channels are Actually 2 Outputs, Left and Right

  26. FXDirect Messages • Message Area of the Platform Shell • Run-time and Initialization Messages • Always Look at this Area When There is Trouble

  27. FXDirect Hands-onand Demo

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