Software Design Of Multi-Channel Aerial Video Encoder Based On DM8168 Processor

With the rapid development of unmanned aerial vehicle technology,its related derivatives spring up,especially aerial video technology.It has good application value in both military and civil fields.In view of the characteristic of aerial images,including multiple channel,high resolution,high frame rate and large scene,encoding software not only needs support multi-channel video compression for the local storage function,but also needs support high-quality and low bit-rate image compression for the remote transmission function.Therefore,a multi-channel video encoding software is designed for aerial vehicle based on DM8168,which is a heterogeneous multi-core processor from Texas Instruments,the main contents are as follows:First,CCS integrated development environment and DVR-RDK software development package are introduced.And DM8168 system software platform is built,including clipping,configuring,and compiling both of U-Boot and Linux system kernel,configuring the cross-compilation environment and the network file system,as well as making UBI file system.Second,a multi-channel HD video transmission system is designed for unmanned aerial vehicle(UAV).Firstly,FPGA converts dual camera video into YUV422 format.Then,DM8168 encodes these video by H.264 video hardware accelerator and sends the code stream back to FPGA by GPMC protocol.Finally,FPGA transmits the code stream to the ground station through the wireless communication device.Third,a aerial video multi-channel coding software module is designed for the aerial video multiple coding.First,the operating mechanism of multi-channel coding framework is analyzed deeply.Then,multi-core task assignment and data stream link are designed based on McFW for realizing two-way acquisition and four-way coding.And a H.264 encoding-level adaptive mechanism is optimized based on the video resolution and frame rate for reducing memory consumption in the coding process.Besides,GPMC driver is developed for transmitting code stream to FPGA.Finally,aiming at working in harsh electromagnetic environment of the aircraft,an anomaly detection mechanism is designed for the coding module to ensure the reliability of the video data.Fourth,a region-of-interest(ROI)coding algorithm based on H.264 compression domain is designed for improving the video quality of the foreground motion area of aerial image in low bandwidth transmission.Firstly,according to the human vision system's sensitivity to the moving object and the foveal visual mechanism,The algorithm employ the motion vector generated in the H.264 video coding process to detect the moving regions(foreground video objects).Secondly,the region of interest is selected according to the detection result and the coding parameters of the region are updated.The region-of-interest coding has been implemented on the DM8168 processor by the ROI interface function of the encoder.