跳至主要内容

小话codec之xvid与264

从别人那拷了2张欧美怀旧经典的VCD,共1.2G。总嫌硬盘太小,莫非是我太贪心?No,压缩的必要性。。。。。。(胡言乱语一通)
可能是因为毕业论文做了H.264的缘故吧,对264有特别的喜好之情,正好一直搞的是不太实际的学术研究,而现在x264的编解码器已经有directshow的codec了,拿来实战演习。
(1)视频用了x264的默认配置(QP=26),音频用mp3来重压,编码时间要4分多钟,压缩后有8.5M。
我的妈,这么慢,2张VCD有32首曲,这样下去得花2个小时去了,换个试试
(2)视频用Xvid,默认配置,音频同样mp3,56k,44khz的,编码时间只要2分钟,压缩后有10.3M。
速度还不错呀,压缩率低了一点点,原视频数据是36.8M,算算看
用x264的码率节省为:1-8.5/36.8 = 76.9%
用Xvid的码率节省为:1-10.3/36.8 = 72.0%
在编码时间上,Xvid仅为H.264的一半,视频效果看起来没分别,没有PSNR还真不好比。
不过,播放经H.264编码的视频,完全不能拖嘛,解码速度没跟上,太慢了,Xvid没有明显的延迟,如果不是压什么很长的片子,就用Xvid来压,不会大多少的,少了4%而已。当然x264的codec还可以再设设,运动搜索方法是六边形搜索法,如果改用不对称六边形搜索法应该会快且好些,全局搜索不推荐了,实用价值小,结果不一定最优。在模式选择部分,可以把默认的High Quality调成RDO,这估计会增加一倍的编码时间。
看来要使264完全实用还有一定距离,不禁要想,在目前的硬件条件尚不能达到情况下,为什么要搞这么复杂的标准。其实不然,标准是有一个生存期限的,代表了当前技术的发展方向,如果标准制定的东西没有实现难度,那技术还怎会有发展的动力呢,想想C++标准出来这么多年,不也有很多编译器尚不能完全符合标准么?不过正因为这样,才会有各厂家技术的竞争,推动科技的前进,我还是挺看好264的。

评论

此博客中的热门博文

反转剧

这两天明显感到天气转冷,呱呱的家里也已经下起了大雪,南京则是阴冷潮湿,让人没有了出行的欲望。没想到躲在被子里看反转剧也成了度过寒冬的一剂良药。在PPLive越来越让人失望的时候,PPStream横空出世,虽然广告仍是少不了的主题,但从视频质量和播放连续性上来说都超过PPLive,实为居家必备之良品(由此可见,新事物一定会战胜旧事物......)。韩国的反转剧最近似乎比较流行,称之为反转剧就在于其结果总是让人出乎意料,不合常理,其间又不乏各种搞怪搞笑的镜头,各种当红帅哥美女也一定让DDMM们爱不释手,20~30分钟一集的剧情一改韩剧拖沓的风貌,想看就看,容易切入。 反转剧,今天你看了吗?

from cpp to java

when i start to study java with a cpp background, i find it is very difficult to convert my mind. i always think how some features in cpp was implemented in java, this give me a little reject to java language. though java is born from c, i think they still have different applicable domains, so try to study both is good for me, and java is a pure OO language, i believe it will give me a better understanding on OOD.

Personalized Google Home

Using your google account, you can create a personalized homepage. You can customize several modules, including various news, gmail, bookmarks. This service is similar to what http://www.netvibes.com/ provides. The drawback is the inconvenience of bookmark module. It doesn't provide grouping while netvibes provide tags to implement this. Wishing google will improve this defect in the near future. Meanwhile, the Live plan of Microsoft is also going on. MS presents several several servicies to counterattack google's counterparts. Virtual Earth (see http://preview.local.live.com ) is a recent service. It provides map service just like google earth, provides a virtual tour better than google. Imaging driving a car in the map and seeing everything real, maybe you can do a virtual europe tour now. Seems interesting. MS also provides a customized home, you can log into www.live.com via your msn accounts. I haven't tried that yet.