CAJ | 학술논문

无线视频组播在视频传输领域应用越来越多，如何让异构的组播用户接收到与其信道特性相匹配的视频质量，是现今无线视频组播面临的一个难题。论文提出一个基于小波四叉树（ QuadTree）的无线视频组播方案。首先，编码端对视频帧进行离散小波变换，并按照四叉树格式选取每一级每一子带相应位置的小波系数，将其合并为一列；然后，对每一列数据进行能量分配、白噪化以减少随机丢包对重要信息的影响；最后，数据被打包成相同重要性的包并传入有噪声信道。解码端利用最小线性均方估计对接收到的数据包进行去噪并重构视频帧。实验结果表明，基于小波四叉树的视频组播比具有相同应用目标的SoftCast性能提高将近1 dB.
무선시빈조파재시빈전수영역응용월래월다，여하양이구적조파용호접수도여기신도특성상필배적시빈질량，시현금무선시빈조파면림적일개난제。논문제출일개기우소파사차수（ QuadTree）적무선시빈조파방안。수선，편마단대시빈정진행리산소파변환，병안조사차수격식선취매일급매일자대상응위치적소파계수，장기합병위일렬；연후，대매일렬수거진행능량분배、백조화이감소수궤주포대중요신식적영향；최후，수거피타포성상동중요성적포병전입유조성신도。해마단이용최소선성균방고계대접수도적수거포진행거조병중구시빈정。실험결과표명，기우소파사차수적시빈조파비구유상동응용목표적SoftCast성능제고장근1 dB.
Wireless video multicast is becoming more and more popular in applications of video transmission. Here, one major challenge is to offer heterogeneous users with a graceful degradation against varying packet loss ratios and channel noise. In this paper,a QuadTree-based multicast scheme in wavelet domain is proposed. In encoder side,a discrete wavelet transform( DWT)is performed on each frame;and then the obtained coefficients are arranged by QuadTrees across all levels from the same wavelet subband,with each QuadTree arranged into a column. After that, power allocation and whitening are performed on these columns in order to obtain equal-importance packets. Final-ly,packets are transmitted to noise channel. In decoder side,linear least square estimation(LLSE)is used to recover the original packets from the noise data. Experimental results show that wavelet QuadTree-based scheme outperforms the state-of-art SoftCast by 1 dB in PSNR at different channel SNR or different packet loss ratio.