摘要
由于无线信道带宽的限制,图像数据在传送前要经过压缩处理。压缩过程中采用的变长编码使压缩数据对信道噪声非常敏感:如果一个码字在传输过程中发生错误,其后续所有码字都可能受到误码的影响,从而导致重建图像的质量急剧下降。因而,无线信道的信道质量可能不会太好,数据的传输误码率可能会比较严重。在宏块数据间插入同步标志是限制误码扩散的一种简单有效的方法,并且有利于解码端进行误码定位、对内容的快速搜索等,其缺点是引入了编码冗余。本文以JPEG压缩体制为背景提出采用一种特殊的码字作为宏块同步标志,一方面尽可能降低编码冗余,另一方面通过增加同步标志与数据码字之间的汉明距离,提高同步码字本身的抗误码性能。实验结果表明,这种方法效果较好。
Due to the bandwidth constraints of wireless channels, the image data should be compressed before being transmitted. As VLC is applied in compression, the compressed data is highly sensitive to the channel noise., a transmission error in a codeword will not only affect the underline codeword but also affect the subsequent code words, resulting in a great degradation of the received image. To constrain error propagation, it is a simple and very efficient way to insert synchronization markers between macro-block data, which also makes the subsequent data recover and the error concealment more effective. In this paper, we suggest to use a kind of special codes as synchronization markers： on the one hand it minimizes redundancy ; on the other hand, it enhances the synchronization markers error-resilience by increasing the hamming distance between the marker and the data code.
出处
《计算机工程与科学》
CSCD
2007年第7期45-48,共4页
Computer Engineering & Science
基金
国家自然科学基金资助项目(60572176)
关键词
图像通信
变长码
同步标志
image transmission
VLC
synchronization marker
