H.264中基于多宏块模式的时域误码掩盖算法

Temporal Error Concealment Based on Variable MB Mode in H.264

视频压缩码流在信道传输时,由于受到信道带宽或者稳定性的影响,容易发生数据的损坏或者丢失,这样不仅会对当前的视频帧产生影响,而且差错会延续到随后的视频帧,因此,需要采用某种技术来降低差错的影响。新一代视频压缩标准H.264支持多种分块大小的运动补偿,分块大小范围从16×16到4×4,因此,在H.264中一个宏块最多可能有16个运动矢量,这些信息都可以用于时域的误码掩盖。为此,提出了一种基于多宏块分割模式的时域误码掩盖算法,根据相邻宏块的分割模式,每个丢失宏块被自适应的划分为大小不同的子块进行掩盖。实验结果表明,该算法可以得到比传统算法更好的视频质量。

When compressed video stream is transmitted over internet or wireless network, it is sensitive to packet loss and error occurrence due to the limited bandwidth and the instability of the channel, especially for motion compensation based video coding standard. An error in one frame not only debases the reconstructed quality of the current frame, but propagates to the succeeding frames which use current frame as their reference frame. As a result, error concealment algorithms are developed for hiding erroneous blocks by exploiting high correlation in video sequence. New coding standard H. 264 supports motion compensation block sizes ranging from 16×16 to 4×4, therefore each MB can have up to sixteen motion vectors. All of these information can be used for temporal error concealment. In this paper, an effective temporal error concealment algorithm based on variable MB mode is proposed. Depending on the modes of neighboring MB, each lost MB is concealed on the basis of different block sizes. Simulation results show that the proposed method yields better video quality than conventional approaches.