Apr 212014
 

First of all, remove xpra and cython if you had them installed:

aptitude purge xpra cython

Update your package lists, as we are going to install a lot of packages:

aptitude update

Prepare required prerequisites

Then follow the instructions on the xpra Wiki for building Ubuntu / Debian style:

apt-get install libx11-dev libxtst-dev libxcomposite-dev libxdamage-dev \ python-all-dev python-gobject-dev python-gtk2-dev

apt-get install xvfb xauth x11-xkb-utils
apt-get install libx264-dev libvpx-dev libswscale-dev libavcodec-dev

The file mentioned in the how-to, vpx.pc should exist:

cat /usr/lib/pkgconfig/vpx.pc

You will need to install and compile Cython from sources, as the version in the Raspbian repository is too old (0.15.1 vs. 0.16 minimum needed).

wget http://www.cython.org/release/Cython-0.20.1.tar.gz
tar -xzf Cython-0.20.1.tar.gz

change into the newly extracted directory. Install cython:

python setup.py install

This will take quite a while. Test that you have the correct cython version:

cython --version

should yield Cython version 0.20.1

Download and extract source

wget https://www.xpra.org/src/xpra-0.12.3.tar.bz2
tar -xjf xpra-0.12.3.tar.bz2

Note: there may be a newer package, check, please.

Change into the extracted directory. We need to apply a patch:

patch < patches/old-libav.patch

Enter xpra/codecs/dec_avcodec/decoder.pyx as the file to patch

Next patch (several files in one go):

patch < patches/old-libav-pixfmtconsts.patch

Simply copy and paste the “Index file” the patcher asks for, for example xpra/codecs/csc_swscale/colorspace_converter.pyx

Next patch (also several files):

patch < patches/old-libav-no0RGB.patch

Act like above (copy & paste file name, without leading / ).

It also contains a useful README, which tells you the next step is:

./setup.py install --home=install

After the compilation is done, you should either (always) set the Pythonpath to include the install subdirectory, like this:

export PYTHONPATH=$PWD/install/lib/python:$PYTHONPATH

or install the “finished” files to the appropriate targets. From the install directory do:

cp bin/* /usr/bin/.
cp -R lib/* /usr/lib/.
cp -R share/* /usr/share/.

xpra will now be the newest version:

xpra –version

xpra v0.12.3

You will still have to set the PYTHONPATH to the new files in /usr/lib/python, though:

The PYTHONPATH environment variable needs to be set:

export PYTHONPATH=/var/lib/python:$PYTHONPATH

 

Test & Test results

OK, here’s how to set up a test session:

Set up a test server, which has xpra installed (you can install it through the winswitch packages, will get you the newest xpra version on Ubuntu & Debian)

Start X Windows, open LXTerminal, run the following commands.

export PYTHONPATH=/var/lib/python:$PYTHONPATH

Start an xpra session via SSH (can be killed using Ctrl-C, and reconnected to using the same command):

xpra start ssh:maxcs@192.168.1.61:122 –start-child=xterm –encoding=h264

Read the manpage (man xpra) to have a look at some other options

Test results

xpra-raspberry-h264

rgb, png encodings are too high-latency.

jpeg is barely usable, even when resizing the application (for instance Abiword) to not full-screen usage.

webm encoding delivers worse quality, but seems a bit more usable

h264 decoding is NOT done in hardware in the default code (we’ll look into this). Surprisingly it is still the “most fluid to use” one.

I suspect that no decoding in H.264 is taking place, and server side xpra falls back to a different encoder (webm?) Anyways, one can even “watch” videos (a couple of frames each second with heavy artifacts) with this.

For very light administration / checking of remote contents, etc. xpra can be used as is. We will need to enable hardware decoding of h264, though, for it to yield real benefits.

Please note: our interests solely rest in streaming TO the Raspberry Pi, not FROM the Raspberry Pi – we will not test / patch in order to speed up administration of the Pi at this point.

 

Notes & Further reading

Dependencies of xpra package:

(you can show this using “apt-cache showpkg xpra” on a machine which has the package in the newer version, e.g. Ubuntu AMD64):

Dependencies:
0.12.3-1 – python2.7 (0 (null)) python (2 2.7.1-0ubuntu2) python (3 2.8) libavcodec53 (18 4:0.8-1~) libavcodec-extra-53 (2 4:0.8-1~) libavutil51 (18 4:0.8-1~) libavutil-extra-51 (2 4:0.8-1~) libc6 (2 2.14) libgtk2.0-0 (2 2.24.0) libswscale2 (18 4:0.8-1~) libswscale-extra-2 (2 4:0.8-1~) libvpx1 (2 1.0.0) libx11-6 (0 (null)) libx264-120 (0 (null)) libxcomposite1 (2 1:0.3-1) libxdamage1 (2 1:1.1) libxext6 (0 (null)) libxfixes3 (0 (null)) libxrandr2 (2 4.3) libxtst6 (0 (null)) python-gtk2 (0 (null)) x11-xserver-utils (0 (null)) xvfb (0 (null)) python-gtkglext1 (0 (null)) python-opengl (0 (null)) python-numpy (0 (null)) python-imaging (0 (null)) python-appindicator (0 (null)) openssh-server (0 (null)) python-pyopencl (0 (null)) pulseaudio (0 (null)) pulseaudio-utils (0 (null)) python-dbus (0 (null)) gstreamer0.10-plugins-base (0 (null)) gstreamer0.10-plugins-good (0 (null)) gstreamer0.10-plugins-ugly (0 (null)) python-gst0.10 (0 (null)) openssh-client (0 (null)) ssh-askpass (0 (null)) python-numeric (0 (null)) python-lz4 (0 (null)) keyboard-configuration (0 (null)) xpra:i386 (0 (null))

CheckInstall

Optional: install checkinstall, to create a package which you can easily remove or re-deploy to other computers:

aptitude install checkinstall

 

Troubleshooting

Patches

error: implicit declaration of function ‘avcodec_free_frame’

you need to apply the patch patches/old-libav.patch

error: ‘AV_PIX_FMT_YUV420P’ undeclared

you need to apply the patch patches/old-libav-pixfmtconsts.patch

error: ‘PIX_FMT_0RGB’ undeclared

you need to apply the patch patches/old-libav-no0RGB.patch

The other patches were NOT needed in my experimental compilation.

 

ImportError: No module named xpra.platform

Once you try to execute xpra (from LXTerminal preferably), you may get this message. The PYTHONPATH environment variable needs to be set:

export PYTHONPATH=/var/lib/python:$PYTHONPATH

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