【作者】 王旭辉；

【导师】 张民选；

【作者基本信息】 国防科学技术大学 ， 电子科学与技术， 2006， 硕士

【摘要】 音视频编/解码技术的实现方法主要有采用专用编/解码芯片和基于DSP的软件编/解码两种技术。后者因其具有较强的灵活性、可扩展性和可控性,逐渐成为主流的编/解码技术之一。视频处理的一大特点在于其高数据流量和高带宽消耗,因此存储接口的性能就成为了影响视频DSP性能的关键因素之一。我校研制的YHFT-Dx高性能DSP处理器具有很强的处理能力,然而其存储访问速度极大的限制了其音视频处理能力。本文针对YHFT-Dx需进一步提升存储访问速度的需求,设计实现了YHFT-Dx的外部存储器接口,扩展了YHFT-Dx的存储访问能力,使其可以同时支持DDR2 SDRAM存储器和异步存储器。设计中采用了基于异步FIFO的缓冲、固定请求优先级下的令牌轮转、基于Cache行偏移量优先读取、双通道多频率存储控制等设计技术,有效提升了流媒体存储访问速度。论文给出了读写请求派发、读写请求缓冲、DDR2访问控制器、异步访问控制器、控制寄存器组等各部件的详细描述,并进行了详细的模拟验证。通过本文的工作,YHFT-Dx不但能够更好地支持异步存储器,还能够支持速度更快,容量更大的DDR2 SDRAM存储器。支持DDR2 SDRAM的存储接口的配套实现,使得进一步提高视频DSP的性能和适用范围成为可能,也为今后进一步的研究打下了良好的基础。更多还原

【Abstract】 The technology for audio/video coding/decoding is mainly implemented by two methods, the specific coder/decoder chips, and the coding/decoding algorithms based on DSPs. The latter becomes the mainstream for video coding/decoding due to its strong flexibility, extendibility and controllability. High data stream and bandwidth requirement is the main characteristic of video processing. Thus, the performance of memory interface is vital to VDSP. The high-performance DSP processor YHFT-Dx designed by our university has strong processing ability, but the low speed of memory access limits its utilization for audio/video coding/decoding.To improve the speed of memory access of DSPs, an innovative external memory interface for YHFT-Dx is proposed in this thesis, which enhances the interface access ability. The key technologies of this design include the asynchronous FIFOs based on buffers, the fixed request priority based on circling token, first reading based on the cache offset, and memory controlling of double channels and multi-frequency. Furthermore, this thesis gives the detail design of read/write requests dispatching unit, the buffer unit of read/write requests, the memory control unit of DDR2 SDRAM, the memory control unit of asynchronous memories, unit of controlling registers and some other components, and gives the detail function verification for this module. The external memory interface designed for YHFT-Dx can support not only asynchronous memories but also DDR2 SDRAM which have higher operation frequency and larger capacity.The implementation of memory interface supporting DDR2 SDRAM memories further improves the performance of VDSP, expands its application range, and lays a good foundation for further study.更多还原