CAJ | 학술논문

在低比特率环境下，如何提高图象编码质量是许多人感兴趣的课题，针对此问题，提出了一种面向对象分配带宽（OOBA）的视频编码器，用以提高低比特率环境下编码图象的主观质量，在充分考虑人的主观视觉特性的基础上，该编码器把图象序列分成不同的视频对象，而每个对象以宏块为单位构成，并且对每个对象单独分配大小不同的带宽，以把更多的比特分配给主观感兴趣的对象，来达到在低比特率环境下提高编码图象主观视觉质量的目的.虽然每个对象独立编码，但在比特流的组织上却能与H.263兼容.为了合理地在多个对象间分配带宽，还给出了基于速率-失真(R-D)模型、基于序列分析和比值加权法等3种带宽分配方法.实验结果表明，该编码器与传统的基于帧的编码器相比，在极低的速率下，峰值信噪比虽略有降低，但图象的主观视觉质量却得到较大的提高.从而表明了该编码器的有效性，也说明在低比特率环境下，仅以客观准则作为评价编码器好坏的标准是不够的.
재저비특솔배경하，여하제고도상편마질량시허다인감흥취적과제，침대차문제，제출료일충면향대상분배대관（OOBA）적시빈편마기，용이제고저비특솔배경하편마도상적주관질량，재충분고필인적주관시각특성적기출상，해편마기파도상서렬분성불동적시빈대상，이매개대상이굉괴위단위구성，병차대매개대상단독분배대소불동적대관，이파경다적비특분배급주관감흥취적대상，래체도재저비특솔배경하제고편마도상주관시각질량적목적.수연매개대상독립편마，단재비특류적조직상각능여H.263겸용.위료합리지재다개대상간분배대관，환급출료기우속솔-실진(R-D)모형、기우서렬분석화비치가권법등3충대관분배방법.실험결과표명，해편마기여전통적기우정적편마기상비，재겁저적속솔하，봉치신조비수략유강저，단도상적주관시각질량각득도교대적제고.종이표명료해편마기적유효성，야설명재저비특솔배경하，부이객관준칙작위평개편마기호배적표준시불구적.
How to improve the subjective visual quality of the video coded at low bit-rate is an interested subject of many people. This paper proposes a video coding system based on object-oriented bandwidth allocation(OOBA) technology to improve the subject quality of coded images. Exploiting human subjective visual characteristic sufficiently, this coder divides video sequence into multi video objects(VO) and allocates more bandwidth for the VO with more subjective significance to improve subjective quality of images coded at low-bit-rate. Each object is composed of macroblocks and coded separately. In bit stream context, the OOBA coder is compatible with H.263. For reasonable bandwidth allocation, present three schemes to allocate bandwidth for multi objects: rate-distortion(R-D) model based scheme ,sequence analysis based scheme and ratio weighting scheme. The result of experiments shows that the PSNR of OOBA coder is a little lower than that of frame-based coder, but the subjective quality is much better. So, it proves the OOBA coder effective and indicates it is not enough to evaluate a video coder only with objective criterion such as PSNR.