On 03/04/2013 05:42 PM, Nick Burrett wrote: > On 4 March 2013 09:00, Antoine Martin <[email protected]> wrote: >> Hi Nick, >> >> xpra is a compositing window manager, and AFAIK this requires 24bpp or >> higher. I've tried launching Xvfb/Xdummy with 8bpp and Composite gets >> turned off. The -pixdepths switch does not help here. FYI: xpra seems to >> crash rather than exit gracefully, but that's another problem. >> >> As for achieving bandwidth savings by reducing the colour depth, x264 >> and vpx encodings use colour subsampling when the quality is lowered >> (switching from 4:4:4 to 4:2:2 and 4:2:0), this is in the chroma+luma >> space rather than plain RGB, but it does save about 50% on image size. >> Also note that newer encodings (x264, webp, etc) are vastly superior to >> the encodings found in VNC, so the bandwidth usage should already be >> much lower (even without colour subsampling). > > Alright, that makes sense. My gnome-terminal data transfer showed as > 420Mbytes for around 6 hours of operation (using x264). I'll have a > go at tuning the quality some more and extend the time between full > window refreshes. > > I wonder if there's some efficiency to be gained by pre-processing the > image before compression (at the expense of quality) -- perhaps by > masking out the bottom 3 bits of R, G and B values so that the > compressors don't have to try to handle subtle colour variations. > >> >> If you find that the quality/bandwidth/framerate/latency isn't good >> enough for you use case, let me know - it is quite possible that recent >> versions have focused a little bit too much on the LAN usage scenario.. > > It's not great at the moment -- it can take 2-3 seconds to switch a > tab in gnome-terminal, for example. But I'd rather ensure that I've > exhausted my client option settings first. 2 to 3 seconds is way too high, I doubt you can find enough options to lower that enough to make it bearable. There is a lot of information for debugging such problems here: https://www.xpra.org/trac/wiki/WindowRefresh#Debugging Let me know what you find and I can make sure this gets auto-tuned properly.
Cheers Antoine > > Regards, > > Nick > >> >> >> On 03/03/2013 07:26 PM, Nick Burrett wrote: >>> Hi, >>> >>> Is it possible to reduce the colour depth client side when performing >>> xpra attach? >>> >>> I'm attempting to use xpra over a 3G modem link where the X server is >>> 140ms away. For a while, I've been using a VNC setup in exactly this >>> way and found that reducing the colour from 24bits to 8bits had a >>> considerable impact on usability. >>> >>> Xvfb has a -pixdepths option, which appears to be a list of supported >>> colour depths. I just would like to get the client to allow the >>> choice to be determined at connection time. >>> >>> Regards, >>> >>> Nick. >>> _______________________________________________ >>> shifter-users mailing list >>> [email protected] >>> http://lists.devloop.org.uk/mailman/listinfo/shifter-users >>> >> >> _______________________________________________ >> shifter-users mailing list >> [email protected] >> http://lists.devloop.org.uk/mailman/listinfo/shifter-users _______________________________________________ shifter-users mailing list [email protected] http://lists.devloop.org.uk/mailman/listinfo/shifter-users
