The study and implementation of embedded MPEG-4 image encoder for spacecraft
Lihua Zuo, Qingxue Wu, Zhuang Tian · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2005
Images of astronauts must be transmitted to the earth in a low bit rate so as to lessen the tension of channel in spacecraft. In this paper, an approach to 384kbps Image Encoder for spacecraft is presented. With FPGA and special chips, a prototype which has a feature of lower time delays, better performance of motion estimation and higher resolution has been designed and implemented. This paper explores the motion compensation and texture coding as the basic coding structure, the MPEG-4 Image Encoder is coded in a content-based and object-based modern method, according to the thought of contour-texture. The coding module is the kernel component of the system that performs the DCT, quantification, motion texture coding, motion estimation and motion compensation, etc. Meanwhile, the digital video signals are compressed by this one. Pursuant to MPEG-4 standard, inter-frame coding and intra-frame DCT are adopted to reduce temporal and spatial redundancy. Variable length coding is also used to match the bit length and the signal frequency, in order to lower the bit rate further more. The bit rate ultimately reaches 384kbps. In special chips, data processing, transforming, coding, estimating and compensating are controlled by DSP which cooperates with FPGA. Error correction coding is also implemented by special chips under the control of DSP.