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在H.264/AVC编码器中,由于采用了固定长度的图像组(GOP)结构,不能有效地处理视频序列中的场景切换,导致场景切换帧后续各帧编码质量严重下降。为了有效解决该问题,提出一种自适应的码率控制算法,通过场景切换的快速检测方法检测视频序列中的场景切换,在场景切换帧处终止当前GOP并对GOP层的码率分配算法做出修正。仿真结果表明:采用该算法可以有效地降低场景切换对后续帧编码质量的影响,而且合理地分配码率资源,提高了整个视频序列的编码质量。在相同码率条件下,整体编码质量可以提高0.3~0.5 dB。
In H.264 / AVC encoder, because of adopting a fixed length GOP structure, scene switching in the video sequence can not be effectively handled, resulting in serious degradation of coding quality of subsequent frames in the scene switching frame. In order to solve this problem effectively, an adaptive rate control algorithm is proposed. The scenario switching in the video sequence is detected by the fast scene change detection method. The current GOP is terminated at the scene switching frame and the rate allocation algorithm of the GOP layer is made Revised. Simulation results show that the proposed algorithm can effectively reduce the impact of scenario switching on the quality of subsequent frames and allocate rate resources rationally to improve the coding quality of the entire video sequence. Under the same code rate, the overall coding quality can be increased by 0.3 ~ 0.5 dB.