Research Article Network-Aware Reference Frame Control for Error-Resilient H.264/AVC Video Streaming Service Hui-Seon Gang, Goo-Rak Kwon, and Jae-Young Pyun Department of Information and Communication Engineering, Chosun University, 309 Pilmun-daero, Dong-gu, Gwangju 61452, Republic of Korea Correspondence should be addressed to Jae-Young Pyun; jypyun@chosun.ac.kr Received 7 August 2015; Revised 21 December 2015; Accepted 15 February 2016 Academic Editor: Qi Wang Copyright © 2016 Hui-Seon Gang et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. To provide high-quality video streaming services in a mobile communication network, a large bandwidth and reliable channel conditions are required. However, mobile communication services still encounter limited bandwidth and varying channel conditions. Te streaming video system compresses video with motion estimation and compensation using multiple reference frames. Te multiple reference frame structure can reduce the compressed bit rate of video; however, it can also cause signifcant error propagation when the video in the channel is damaged. Even though the streaming video system includes error-resilience tools to mitigate quality degradation, error propagation is inevitable because all errors can not be refreshed under the multiple reference frame structure. In this paper, a new network-aware error-resilient streaming video system is introduced. Te proposed system can mitigate error propagation by controlling the number of reference frames based on channel status. Te performance enhancement is demonstrated by comparing the proposed method to the conventional streaming system using static number of reference frames. 1. Introduction Today, high-quality video content is a basic requirement of multimedia services and is becoming important in mobile communication systems. Because of the low cost of powerful processors and the advancement of mobile communication services, consumers are able to use high-defnition multi- media streaming services on their hand-held devices. Tese multimedia streaming data have been compressed for storage and transmission. Even though many service providers have developed and provided advanced mobile communication services, it remains difcult to reliably transmit high-quality video streams because of the varying channel conditions and limited available bandwidth of wireless channels. Te current streaming video system generally uses mo- tion estimation and compensation procedure at encoder and decoder, respectively, for a high coding efciency feature. Tis system considerably reduces the number of bits to encode because it utilizes multiple reference frames to remove temporal redundancy. Because of its high coding efciency, H.264/AVC and H.265/HEVC are suitable for the streaming system transmitting high-quality video sequences in the en- vironments that have limited channel capacity [1]. However, if the encoded sequences are damaged by channel errors, the damage can be propagated to neighbor- ing macroblocks (MBs) and frames. Even though motion estimation using multiple reference frames can signifcantly decrease the number of data bits that must be encoded, the compressed sequence can be vulnerable to error propagation. To mitigate the impact of error propagation, the streaming video system includes error-resilience tools. Error-resilience tools preprocess the video data either by reordering each macroblock’s coding sequence or by inserting redundant data, such that the damaged blocks can be spreaded out (espe- cially in the case of burst errors). Tat is, the damaged video is improved by error-resilience tools. Tese tools can make the encoded video sequence more robust to errors, but coding efciency will be decreased because of the additional bits [2]. Among the typical error-resilient methods, intrarefresh (IR) algorithm is used ofen to avoid error propagation in a distorted video sequence over an error-prone network. When IR algorithm is used as an error-resilience method, multiple Hindawi Publishing Corporation Mobile Information Systems Volume 2016, Article ID 9076086, 11 pages http://dx.doi.org/10.1155/2016/9076086