touch-packages team mailing list archive

[Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>]

More or less. In 1.12, there was no difference in quality between FAST
and BEST, both used a bilinear filter. For 1.14, there was a desire
(mainly driven by inkscape and firefox) to have better image quality
when scaling - hence the switch to a convolution filter for BEST
resampling. So FAST remains the same, but BEST is slower for higher
quality. The default in cairo is to use BEST.

The guiding principle is to keep data on the gpu if it ever touches the
gpu, so if either your source is in hardware or the destination is, then
you should be using a cairo_surface_t suitable for rendering on the same
hardware. Otherwise, whether offloading the rendering onto a gpu is a
benefit requires experimentation - but often fun experimentation ;-)

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https://bugs.launchpad.net/bugs/1360606

Title:
  libcairo.so for Ubuntu 14.04 is dead-slow compared to Ubuntu 13.10

Status in “cairo” package in Ubuntu:
  New

Bug description:
  I'm running the video mixer software called Snowmix that uses libcairo
  extensively. After updating to Ubuntu 14.04 Desktop amd64, I noticed
  that mixing video required 8 times more CPU compared to Ubuntu 13.10.
  Using oprofile I discovered the heavy CPU load was taking place in
  libpixman used by libcairo. However libpixman is currently the same
  release in Ubuntu 14.04 and 13.10. However I did notice that libcairo
  got upgraded from libcairo.so.2.11200.16 in Ubuntu 13.10 to
  libcairo.so.2.11301.0 in Uuntu 14.04.

  Snowmix uses libcairo2 primarily for scaling and rotating images and
  overlay them in memory.

  Replacing libcairo.so.2.11301.0 with libcairo.so.2.11200.16 in Ubuntu
  14.04 lower the CPU usage by at least 8 times. So I suspect that
  libcairo for Ubuntu 14.04 somehow got compiled without the hardware
  acceleration such as MMX/SSE2/SSE3 etc. This is quite bad if this is
  the case. If it is not the case, something else is seriously wrong
  with libcairo2.

  1)Description:	Ubuntu 14.04.1 LTS
    Release:	14.04
  2) libcairo2:
      Installed: 1.13.0~20140204-0ubuntu1
      Candidate: 1.13.0~20140204-0ubuntu1
      Version table:
     *** 1.13.0~20140204-0ubuntu1 0
          500 http://dk.archive.ubuntu.com/ubuntu/ trusty/main amd64 Packages
          100 /var/lib/dpkg/status
  3) I expected libcairo2 (libcairo.so.2.11301.0) for Ubuntu14.04 to work as efficient as libcairo2 (libcairo.so.2.11200.16)for Ubuntu13.10.
  4) Libcairo2 for Ubuntu 14.04 works 8 times slower indicating a lack of MMX/SSE2/SSE3 etc acceleration.

  For the source, you have the source for libcairo2 for Ubuntu14.04.

  I can provide you with the source code for Snowmix using libcairo2,
  but I don't expected you need it nor want it.

  Best regards
  Peter Maersk-Moller

  ProblemType: Bug
  DistroRelease: Ubuntu 14.04
  Package: libcairo2 1.13.0~20140204-0ubuntu1
  ProcVersionSignature: Ubuntu 3.13.0-34.60-generic 3.13.11.4
  Uname: Linux 3.13.0-34-generic x86_64
  ApportVersion: 2.14.1-0ubuntu3.3
  Architecture: amd64
  Date: Sat Aug 23 15:23:38 2014
  InstallationDate: Installed on 2013-06-21 (428 days ago)
  InstallationMedia: Ubuntu 12.04.2 LTS "Precise Pangolin" - Release amd64 (20130213)
  ProcEnviron:
   LANGUAGE=en_US:en
   TERM=xterm
   PATH=(custom, no user)
   LANG=en_US.UTF-8
   SHELL=/bin/bash
  SourcePackage: cairo
  UpgradeStatus: Upgraded to trusty on 2014-08-20 (3 days ago)

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