官方解释:
问:
also, in autoRV9, it has options for "normal video" "smooth video" and "sharpest video".. I always use sharpest, but what exactly does puitting it on normal or smooth do? does it pre-process the source?
karl 答:
Glad you asked. That's always been a confusing option, because it affects a few non-documented internal parameters. It was designed mainly for low bitrates, and is the trade-off in the encoder between frame rate and quality/sharpness. So 'sharpest' would be better quality/sharper but skip more frames. There is no pre-filtering. For VBR and higher bitrates, the 'normal' vs 'sharpest' will have very little effect, if any. However, the 'smooth' setting has the following effect: If you choose 'smooth', the encoder will operate in HHR mode (half-horizontal resolution) for video sizes larger than 640x320. HHR means to resample and encode at half the width, and have the player scale back on playback. This looks very smooth, but is a good trade-off for very low bitrates, relative to video size. I rarely use it though. HHR in RealVideo was more common in the past, when 'normal' would use HHR the way 'smooth' does now. We probably should make HHR a separate option.
简单的翻译一下............
sharpest video和normal只影响帧率.......
在码率很低的情况下, 当现有的码率不够的时候, 选sharpest video编码器就会丢掉一些帧来提高画面质量.......
选normal video就会使用很大的in-loop filtering, 使画面变模糊, 保持原来的帧率...........
选smooth video会在视频像素大于640 x 320, 也就是20万像素的时候把横向的分辨率减半, 变320x320来降低码率的需求, 播放的时候再拉伸成640x320.........
在高码率或使用了vbr后, 选sharpest video和normal video就没什么区别了, 因为很少有码率不够的时候..........
说看不出区别的人可能是因为使用了vbr或使用的码率比较高......
