Design and Implementation of Low Latency IP Video Transmission System for Racing Drones Using In-frame Segmented JPEG Compression with Pipelined Processing

In recent years, racing drones have become popular, in which pilots compete for the time to complete laps around a course while watching onboard FPV video. Analog video transmission with low latency is commonly used for racing drones. However, electromagnetic noise degrades image quality in analog video transmission. Conversely, digital IP video transmission has high image quality but suffers increased latency due to frame buffering and encoding processes, and is generally not used in racing drones. In addition, conventional video transmission systems for drones cannot transmit video in out-of-sight communications. To solve this problem, we implemented a low latency HD video transmission system on FPGA by pipelining camera capture processing, image correction processing, encoding processing, and IP transmission in units of 8-line buffers, instead of the frame-by-frame encoding process in the conventional method. We measured the total delay between the camera and the display of an existing video transmission system for drones was measured and compared with the proposed method. The total delay of the proposed method was 30.9 ms, which was more than 100 ms less than the conventional digital video transmission for drones and closer to the analog video transmission of 27.6 ms. We measured the latency for each part of our proposed method, and found the latency of the IP video transmitter was less than 1 ms, confirming that our system can achieve lower latency via pipelining.