Linked by Thom Holwerda on Wed 14th Nov 2012 22:12 UTC
Internet Explorer "In Windows 8, we reimagined the browser with IE10. We designed and built IE10 to be the best way to experience the Web on Windows. With the IE10 Release Preview for Windows 7 consumers can now enjoy a fast and fluid Web with the updated IE10 engine on their Windows 7 devices. The release preview of IE10 on Windows 7 is available for download today."
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RE[11]: IE10 still disappointing
by lemur2 on Sat 17th Nov 2012 10:23 UTC in reply to "RE[10]: IE10 still disappointing"
lemur2
Member since:
2007-02-17

How can you have a "higher average bitrate" within the same filesize?

It's like saying you and I both ran a marathon (filesize) in the same amount of time (clip running time), but you went faster.

One average bitrate can't be higher than the other for a clip of the same length and filesize; they are the same.


With VBR, AFAIK the bitrate refers to the video as rendered, not the video as compressed. Because WebM static compression quality per bit is better than h264, and because most video is lower motion rather than higher motion, WebM can deliver a higher (as rendered) bitrate from the same number of as-compressed bits.

As to your other point: so you have no benchmarks (even screenshots?) to support your claim that WebM has higher quality/bitrate than x264? Okie.


Where WebM suffers in terms of objective measurements is in areas of high motion. Because WebM (deliberately) blurs these high dynamic areas, so as not to waste too many as-compressed bits, they compare very poorly between the rendered still frames and the original still frames, and cause WebM to score poorly on objective measures such as PSNR, even though to the human viewers eye when watching the video at normal speed, the blurring of high motion areas has little detrimental (objective) effect on the as perceived quality.

Due mostly to the blurring of high-motion video, a real-life WebM video can easily be objectively measured in terms of YSSM and PSNR as being lower quality than an h264 video, yet still preferred objectively by a human viewer watching the video at normal playing speed. In addition, if you take a still of the same frame during a low-motion scene from WebM and H264, the WebM still frame will be distinctly clearer and sharper, but on some other frame during a high-motion scene, the H264 still frame will be far cleaer and sharper than the WebM one.

So the perceived quality and the measured quality can be quite different.

I did have some screenshots of this which illustrated the point very well, but I can no longer find them. Sorry about that.

I am not, BTW, claiming that WebM is better than H264. I am merely claiming that it performs differently, and for the purposes of video over the web, just as well as h264.

Edited 2012-11-17 10:24 UTC

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