中文摘要：

为克服无人机视频应用中计算能力和传输带宽的限制,提出一种视频分层表达方法,实现快速、高质量、灵活的视频编码.将无人机视频分为背景层和目标层,并分别采用基于全局运动估计和基于局部块匹配的方法进行压缩,压缩后的码流可以根据实际的网络情况和应用需求进行单独传输或组合传输.实验结果表明：在极低码率如50 kbit/s时,H.264的PSNR低于28 dB,且图像主观质量超出可接受范围,而采用分层表达中的背景层压缩,可以在保证PSNR在28 dB以上,且图像细节清晰、主观质量较高;在码率较高时,采用背景层和目标层结合,在同等码率条件下,目标的细节比H.264更清晰;整个压缩过程消耗的时间只有H.264的18%.本文方法在不降低视频质量的同时提高了压缩效率,且码流具备灵活性,适用于低延时、低带宽、复杂的无人机应用.

英文摘要：

To overcome the limitations of compute capability and bandwidth in UAV（ Unmanned Aerial Vehicle）video,this paper proposes a novel video compression algorithm based on hierarchical description. The video is split into background layer and object layer. Background layer is encoded with global motion estimation,while object layer is encoded with local block matching. The experimental results demonstrate that,when bandwidth is narrow e.g. 50 kbit/s,using background layer encoding can achieve higher PSNR than H.264,and the subjective quality is much more acceptable; in most cases,combining background and object layer can give more details than H.264 with the same bitrate; the consuming time is only 18% of H. 264 ＇s. Additionally,alternative bitstream can be extracted for different bandwidth. Consequently,the proposed algorithm is suitable for low latency and complexity applications in UAV video due to its good performance,high efficiency and flexibility.