An Efficient Encoding Method for Video Compositing in HEVC

Video compositing for compressed HEVC streams is highly demanded in instant communication applications such as video chat. As a flexible scheme, pixel domain compositing involves the processes of completely decoding the streams, inserting the decoded video, and finally re-encoding the new composite video. The time consumption of the whole scheme comes almost entirely from the re-encoding process. In this paper, we propose an efficient encoding method to speedup the re-encoding process and improve encoding efficiency. The proposed method separately designs encoding for blocks inside the frame region covered by inserted video and blocks in non-inserted region, which overcomes numerous difficulties of utilizing information from the decoding process. Experimental results show that the proposed method achieves a \(\text {PSNR}\) increase of 0.33 dB, or a bit rate saving of 10.11% on average compared with normal encoding using unmodified HM software. Furthermore, the encoding speed is 7.04 times that of normal encoding method, equivalent to an average reduction of 85.8% in computational complexity.