Even Rouault <even.rouault <at> spatialys.com> writes: > > Hi, > > For those interested, I've committed an experimental (*) read-only BPG (Better > Portable Graphics) driver to read the new image format created by Fabrice > Bellard based on HEVC : http://bellard.org/bpg/ > For same quality as JPEG, images are typically twice smaller. Competitor of > WebP as well, with apparently slightly better quality. > Rather as dealing with standalone images, it could be interested as a codec in > TIFF for example to benefit from tiling, overviews, etc. Or a GeoPackage tile > format extension.
Hi, Extremely interesting for all that you mention. By quick reading I got an impression that it might be 10 times slower in compression and 2-3 times slower in decompression compared to some video codec. I have no idea about how fast it is to use H.264 codec so I planned to make a quick test with jpeg with my own images by using bpgenc.exe which I found from http://bellard.org/bpg/bpg-0.9.5-win32.zip. With a 19200x19200 sized image it just crashes but I could compress a 3455x3954 sized png. I can confirm that compression is very slow. My topographic map shrink from 475 kb (.png) into 340 kb (.bpg) which is pretty good (-30%) because the original image suits very well for png compression. As a comparison, gdal_translate made a 676 kb jpeg image with the default settings. Remember that this number does not mean anything because the original just does not suit for jpeg. I believe that with GDAL the bpg format would be used with at max. 1024x1024 sized tiles so my tests are probably not worth much value but it feels like reasonable savings in bandwidth could be achieved at rather high cost in CPU usage. Users of tile services and offline maps should be interested but without hardware acceleration bpg could be slow for WMS. However, chips for hardware HEVC compression are already available so it is only upon someone writing code and make GDAL to utilize such things. Hardware accelerated MapServer for fast and small delivery, mmmm, it tastes good. -Jukka Rahkonen- _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
