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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 d B,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 d B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.
In order to overcome the limitation of computing ability and transmission bandwidth in UAV video application, a video hierarchical expression method is proposed to realize fast, high quality and flexible video coding.The UAV video is divided into the background layer and the target layer Respectively, based on global motion estimation and local block matching compression method, the compressed bit stream can be based on the actual network conditions and application requirements for separate transmission or combined transmission.Experimental results show that: at very low bit rates such as 50 kbit / s, the PSNR of H.264 is lower than 28 d B, and the subjective quality of the image is beyond the acceptable range. With the background layer compression in the hierarchical expression, the PSNR can be guaranteed to be above 28 dB with clear detail and subjective The quality is higher; when the code rate is higher, the target layer is combined with the background layer and the target layer, and the detail of the target is clearer than that of H.264 under the same code rate; the entire compression process consumes only 18% of H.264. The proposed method improves the compression efficiency without degrading the video quality and has the flexibility of code stream for low latency, low bandwidth and complex UAV applications.