The Research And IP Core Implementation On Surrounding Technology Based On The HRTF

When peoples pursuit the video playback effect of realistic and presence, they requestmore and more audio playing effect, such as the demand for the sense of presence, surrounded,strength and so on. And then the concept of spatial hearing has been raised. It is known thatthe traditional spatial hearing is mainly emphasizing the interaural time difference (ITD) andthe interaural level difference (ILD), the implementation way is only using the expensivemulti-channel playback system.With the development of digital signal processing technology, the head related transferfunctions (HRTF) theory has been put out. The early HRTF research mainly about theimprovement and analysis of the channel signal of multi-channel playback system, there aremany famous research institutions for measuring and establishing the HRTF database. Whendigital signal processors (DSPs) have been arisen, it provided a re-use researching hardwareplatform for the HRTF researchers, and the concept of virtual space hearing was introduced tothe field of DSP. From the end of the last century, many people using HRTF theory andimplementing virtual auditory playback system.The Virtual Auditory which process the audio signal can simulate the acoustic pressurewhich generated by a real sound source at the corresponding location in the human ear canalby using head related transfer functions, it can give the listener a realistic spatial sound image.The spatial sound effect which implement by this way have many advantages such as simplehardware structure, stability, and it can easily obtain the true and nature sound image. so it hasa very wide range on application field.In recent years, whether in hardware or algorithm, the new digital signal processingtechniques was continuously proposed. For the popularity of FPGA, digital signal processingprovides a new hardware platform, the IP core (Intellectual Property core) was well known asmany related commercialization company were arisen in nowadays. At the same time, FPGAsignal processing platform provided a new playing space for virtual Auditory.We developed an IP core by using HRTF on the FPGA hardware platform. At the first,we reviewed the development of the audio signal processing, and introduced the traditionalspatial hearing theory, and then continuously introduced related theory and the principle aboutthe virtual replay and head related transfer functions, the next content is about designing a IIRfilter by using prony method base the theory above, and applied it to the virtual multi-channelplayback system as a continue, finally we implement this HRTF IP core. The mainly part ofthis IP core was implemented by using a direct type II IIR filter structure, so it can achieve thegoal of high efficiency. Based on this Filter, we deduced a module by adopting the5.1-channel audio playback model, and then obtained a mathematical model of two-channelaudio playback by using5.1-channel audio stream. Finally, we come to a complete digital signal processing. On this basis, we implemented a complete IP core with the Verilog HDLlanguage.And coupled with the FPGA is high-speed when it does signal processing, we build atest system of this IP core. As the preliminary test, the result showed that the IP core has ahigh processing efficiency and good spatial effects features.This IP core has been tested in laboratory, and it has reached the desired goal. It providesa good idea for the HRTF implement on FPGA, especially in space-constrained handhelddevices.