Further analysis reveals that TigerVNC's Compression Level 5 and 6 (which are basically identical when JPEG is enabled) can already produce roughly the same compression ratio (within +/- 5%) as the maximum useful mode in TightVNC 1.3.x, so actually, I think the only thing that might need addressing here is the fact that the higher Zlib levels are not needed for Compression Levels 7-9. I can find no dataset for which moving from CL 6 to CL 9 in TigerVNC produces more than a 5% increase in compression ratio, and generally this move increases CPU time by a factor of 4-5. Thus, I would suggest the following modification, which extends the Zlib levels from CL 6 through CL 7-9 as well:
--- a/common/rfb/TightEncoder.cxx +++ b/common/rfb/TightEncoder.cxx @@ -70,9 +70,9 @@ const TIGHT_CONF TightEncoder::conf[10] = { { 65536, 2048, 12, 6, 7, 3, 32, 96, 62, SUBSAMP_422 }, // 4 { 65536, 2048, 12, 7, 8, 4, 32, 96, 77, SUBSAMP_422 }, // 5 { 65536, 2048, 16, 7, 8, 5, 32, 96, 79, SUBSAMP_NONE }, // 6 - { 65536, 2048, 16, 8, 9, 6, 64, 96, 86, SUBSAMP_NONE }, // 7 - { 65536, 2048, 24, 9, 9, 7, 64, 96, 92, SUBSAMP_NONE }, // 8 - { 65536, 2048, 32, 9, 9, 9, 96, 96,100, SUBSAMP_NONE } // 9 + { 65536, 2048, 16, 7, 8, 5, 64, 96, 86, SUBSAMP_NONE }, // 7 + { 65536, 2048, 24, 7, 8, 5, 64, 96, 92, SUBSAMP_NONE }, // 8 + { 65536, 2048, 32, 7, 8, 5, 96, 96,100, SUBSAMP_NONE } // 9 }; On 1/23/14 4:01 AM, Pierre Ossman wrote: > On Wed, 22 Jan 2014 17:30:25 -0600, > DRC wrote: > >> >> My proposal is for TigerVNC to adopt four compression modes: CL 0, CL >> 1, CL 2, and CL 5. CL 3 and 4 would map to 2, and CL 6-9 would map to >> 5, and the GUI could be restructured so that it sets the compression >> level to "low, high, and very high", with a warning that "very high" is >> only better than "high" in some rare cases. >> >> Just a suggestion. I can provide a server-side patch for this if requested. >> > > Interesting stuff. I'd definitely like to know more about the > discussion and the testing that was done. > > I'm shuffling around all of that code at the moment though, so please > hold off on that patch for a while. :) > > Rgds > ------------------------------------------------------------------------------ CenturyLink Cloud: The Leader in Enterprise Cloud Services. Learn Why More Businesses Are Choosing CenturyLink Cloud For Critical Workloads, Development Environments & Everything In Between. Get a Quote or Start a Free Trial Today. http://pubads.g.doubleclick.net/gampad/clk?id=119420431&iu=/4140/ostg.clktrk _______________________________________________ Tigervnc-devel mailing list Tigervnc-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/tigervnc-devel