Quote:
Originally Posted by singhkays
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"80% better than H.264".
The claimed 50% bit rate reduction of VP9 vs. AVC is not substantiated by independent studies, or in practice by anyone. Also, you can't add bit rate reductions, you have to multiply bit rate ratios. If B encodes to the same quality as A at 0.5x the bit rate, and C encodes to the same quality as B with 0.7x the bit rate, C theoretically is 0.7 x 0.5 = 0.35x the bit rate of A... a 65% reduction, not 80%. But in practice studies have shown that AV1 is roughly on par with HEVC when measured with objective metrics (PSNR, SSIM, VMAF, etc.), delivering roughly a 50% bit rate reduction over AVC. However, measured subjectively it's behind HEVC. Although all of the above measures video, and not still still image compression, I expect the results for image (I frame only) compression to be quite close. Mozilla published a
study in 2013 which confirmed the superiority of HEVC still image compression over other existing formats. Strangely, the link to the study no longer works, but I saved a copy. Maybe one of the Mozilla guys can reshare it.
I agree that content publishers and web sites should be leveraging more powerful video codecs for still image compression. They can start with AVC, as device support is ubiquitous, and it is an improvement over JPEG and GIF. If/when they add support for an advanced codec, they will want the largest range of devices to support that codec, and they will want hardware decoding (for speed and vastly reduced power consumption). They can leverage HEVC (in HEIC container files... based on the ISO Base Media File Format, the evolution of .mov and .mp4) for the majority of devices which already have hardware HEVC support.
See
https://nokiatech.github.io/heif/comparison.html
Google developed the
WebP standard for still image compression, based on VP8 technology. It's only 10% more efficient than JPEG. What you're proposing would seem to be a new version of WebP.