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<rss version='2.0' xmlns:lj='http://www.livejournal.org/rss/lj/1.0/' xmlns:atom="http://www.w3.org/2005/Atom">
        <channel>
                <title>Petter Reinholdtsen</title>
                <description></description>
                <link>http://people.skolelinux.org/pere/blog/</link>
                <atom:link href="http://people.skolelinux.org/pere/blog/index.rss" rel="self" type="application/rss+xml" />
        
        <item>
                <title>Measuring the speaker frequency response using the AUDMES free software GUI - nice free software</title>
                <link>http://people.skolelinux.org/pere/blog/Measuring_the_speaker_frequency_response_using_the_AUDMES_free_software_GUI___nice_free_software.html</link>
                <guid isPermaLink="true">http://people.skolelinux.org/pere/blog/Measuring_the_speaker_frequency_response_using_the_AUDMES_free_software_GUI___nice_free_software.html</guid>
                <pubDate>Mon, 22 Oct 2018 08:40:00 +0200</pubDate>
                <description>&lt;p&gt;&lt;img src=&quot;http://people.skolelinux.org/pere/blog/images/2018-10-22-audmes-measure-speakers.png&quot; align=&quot;right&quot; width=&quot;40%&quot;/&gt;&lt;/p&gt;

&lt;p&gt;My current home stereo is a patchwork of various pieces I got on
flee markeds over the years.  It is amazing what kind of equipment
show up there.  I&#39;ve been wondering for a while if it was possible to
measure how well this equipment is working together, and decided to
see how far I could get using free software.  After trawling the web I
came across an article from DIY Audio and Video on
&lt;a href=&quot;https://www.diyaudioandvideo.com/Tutorial/SpeakerResponseTesting/&quot;&gt;Speaker
Testing and Analysis&lt;/a&gt; describing how to test speakers, and it listing
several software options, among them
&lt;a href=&quot;https://sourceforge.net/projects/audmes/&quot;&gt;AUDio MEasurement
System (AUDMES)&lt;/a&gt;.  It is the only free software system I could find
focusing on measuring speakers and audio frequency response.  In the
process I also found an interesting article from NOVO on
&lt;a href=&quot;http://novo.press/understanding-speaker-specifications-and-frequency-response/&quot;&gt;Understanding
Speaker Specifications and Frequency Response&lt;/a&gt; and an article from
ecoustics on
&lt;a href=&quot;https://www.ecoustics.com/articles/understanding-speaker-frequency-response/&quot;&gt;Understanding
Speaker Frequency Response&lt;/a&gt;, with a lot of information on what to
look for and how to interpret the graphs.  Armed with this knowledge,
I set out to measure the state of my speakers.&lt;/p&gt;

&lt;p&gt;The first hurdle was that AUDMES hadn&#39;t seen a commit for 10 years
and did not build with current compilers and libraries.  I got in
touch with its author, who no longer was spending time on the program
but gave me write access to the subversion repository on Sourceforge.
The end result is that now the code build on Linux and is capable of
saving and loading the collected frequency response data in CSV
format.  The application is quite nice and flexible, and I was able to
select the input and output audio interfaces independently.  This made
it possible to use a USB mixer as the input source, while sending
output via my laptop headphone connection.  I lacked the hardware and
cabling to figure out a different way to get independent cabling to
speakers and microphone.&lt;/p&gt;

&lt;p&gt;Using this setup I could see how a large range of high frequencies
apparently were not making it out of my speakers.  The picture show
the frequency response measurement of one of the speakers.  Note the
frequency lines seem to be slightly misaligned, compared to the CSV
output from the program.  I can not hear several of these are high
frequencies, according to measurement from
&lt;a href=&quot;http://freehearingtestsoftware.com&quot;&gt;Free Hearing Test
Software&lt;/a&gt;, an freeware system to measure your hearing (still
looking for a free software alternative), so I do not know if they are
coming out out the speakers.  I thus do not quite know how to figure
out if the missing frequencies is a problem with the microphone, the
amplifier or the speakers, but I managed to rule out the audio card in my
PC by measuring my Bose noise canceling headset using its own
microphone.  This setup was able to see the high frequency tones, so
the problem with my stereo had to be in the amplifier or speakers.&lt;/p&gt;

&lt;p&gt;Anyway, to try to role out one factor I ended up picking up a new
set of speakers at a flee marked, and these work a lot better than the
old speakers, so I guess the microphone and amplifier is OK.  If you
need to measure your own speakers, check out AUDMES.  If more people
get involved, perhaps the project could become good enough to include
in Debian?  And if you know of some other free software to measure
speakers and amplifier performance, please let me know.  I am aware of
the freeware option &lt;a href=&quot;https://www.roomeqwizard.com/&quot;&gt;REW&lt;/a&gt;,
but I want something that can be developed also when the vendor
looses interest.&lt;/p&gt;

&lt;p&gt;As usual, if you use Bitcoin and want to show your support of my
activities, please send Bitcoin donations to my address
&lt;b&gt;&lt;a href=&quot;bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b&quot;&gt;15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b&lt;/a&gt;&lt;/b&gt;.&lt;/p&gt;
</description>
        </item>
        
        <item>
                <title>Web browser integration of VLC with Bittorrent support</title>
                <link>http://people.skolelinux.org/pere/blog/Web_browser_integration_of_VLC_with_Bittorrent_support.html</link>
                <guid isPermaLink="true">http://people.skolelinux.org/pere/blog/Web_browser_integration_of_VLC_with_Bittorrent_support.html</guid>
                <pubDate>Sun, 21 Oct 2018 09:50:00 +0200</pubDate>
                <description>&lt;p&gt;Bittorrent is as far as I know, currently the most efficient way to
distribute content on the Internet.  It is used all by all sorts of
content providers, from national TV stations like
&lt;a href=&quot;https://www.nrk.no/&quot;&gt;NRK&lt;/a&gt;, Linux distributors like
&lt;a href=&quot;https://www.debian.org/&quot;&gt;Debian&lt;/a&gt; and
&lt;a href=&quot;https://www.ubuntu.com/&quot;&gt;Ubuntu&lt;/a&gt;, and of course the
&lt;a href=&quot;https://archive.org/&quot;&gt;Internet archive&lt;/A&gt;.

&lt;p&gt;Almost a month ago
&lt;a href=&quot;https://tracker.debian.org/pkg/vlc-plugin-bittorrent&quot;&gt;a new
package adding Bittorrent support to VLC&lt;/a&gt; became available in
Debian testing and unstable.  To test it, simply install it like
this:&lt;/p&gt;

&lt;p&gt;&lt;pre&gt;
apt install vlc-plugin-bittorrent
&lt;/pre&gt;&lt;/p&gt;

&lt;p&gt;Since the plugin was made available for the first time in Debian,
several improvements have been made to it.  In version 2.2-4, now
available in both testing and unstable, a desktop file is provided to
teach browsers to start VLC when the user click on torrent files or
magnet links.  The last part is thanks to me finally understanding
what the strange x-scheme-handler style MIME types in desktop files
are used for.  By adding x-scheme-handler/magnet to the MimeType entry
in the desktop file, at least the browsers Firefox and Chromium will
suggest to start VLC when selecting a magnet URI on a web page.  The
end result is that now, with the plugin installed in Buster and Sid,
one can visit any
&lt;a href=&quot;https://archive.org/details/CopyingIsNotTheft1080p&quot;&gt;Internet
Archive page with movies&lt;/a&gt; using a web browser and click on the
torrent link to start streaming the movie.&lt;/p&gt;

&lt;p&gt;Note, there is still some misfeatures in the plugin.  One is the
fact that it will hang and
&lt;a href=&quot;https://github.com/johang/vlc-bittorrent/issues/13&quot;&gt;block VLC
from exiting until the torrent streaming starts&lt;/a&gt;.  Another is the
fact that it
&lt;a href=&quot;https://github.com/johang/vlc-bittorrent/issues/9&quot;&gt;will pick
and play a random file in a multi file torrent&lt;/a&gt;.  This is not
always the video file you want.  Combined with the first it can be a
bit hard to get the video streaming going.  But when it work, it seem
to do a good job.&lt;/p&gt;

&lt;p&gt;For the Debian packaging, I would love to find a good way to test
if the plugin work with VLC using autopkgtest.  I tried, but do not
know enough of the inner workings of VLC to get it working.  For now
the autopkgtest script is only checking if the .so file was
successfully loaded by VLC.  If you have any suggestions, please
submit a patch to the Debian bug tracking system.&lt;/p&gt;

&lt;p&gt;As usual, if you use Bitcoin and want to show your support of my
activities, please send Bitcoin donations to my address
&lt;b&gt;&lt;a href=&quot;bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b&quot;&gt;15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b&lt;/a&gt;&lt;/b&gt;.&lt;/p&gt;
</description>
        </item>
        
        <item>
                <title>Release 0.2 of free software archive system Nikita announced</title>
                <link>http://people.skolelinux.org/pere/blog/Release_0_2_of_free_software_archive_system_Nikita_announced.html</link>
                <guid isPermaLink="true">http://people.skolelinux.org/pere/blog/Release_0_2_of_free_software_archive_system_Nikita_announced.html</guid>
                <pubDate>Thu, 18 Oct 2018 14:40:00 +0200</pubDate>
                <description>&lt;p&gt;This morning, the new release of the
&lt;a href=&quot;https://gitlab.com/OsloMet-ABI/nikita-noark5-core/&quot;&gt;Nikita
Noark 5 core project&lt;/a&gt; was
&lt;a href=&quot;https://lists.nuug.no/pipermail/nikita-noark/2018-October/000406.html&quot;&gt;announced
on the project mailing list&lt;/a&gt;.  The free software solution is an
implementation of the Norwegian archive standard Noark 5 used by
government offices in Norway.  These were the changes in version 0.2
since version 0.1.1 (from NEWS.md):

&lt;ul&gt;
  &lt;li&gt;Fix typos in REL names&lt;/li&gt;
  &lt;li&gt;Tidy up error message reporting&lt;/li&gt;
  &lt;li&gt;Fix issue where we used Integer.valueOf(), not Integer.getInteger()&lt;/li&gt;
  &lt;li&gt;Change some String handling to StringBuffer&lt;/li&gt;
  &lt;li&gt;Fix error reporting&lt;/li&gt;
  &lt;li&gt;Code tidy-up&lt;/li&gt;
  &lt;li&gt;Fix issue using static non-synchronized SimpleDateFormat to avoid 
      race conditions&lt;/li&gt;
  &lt;li&gt;Fix problem where deserialisers were treating integers as strings&lt;/li&gt;
  &lt;li&gt;Update methods to make them null-safe&lt;/li&gt;
  &lt;li&gt;Fix many issues reported by coverity&lt;/li&gt;
  &lt;li&gt;Improve equals(), compareTo() and hash() in domain model&lt;/li&gt;
  &lt;li&gt;Improvements to the domain model for metadata classes&lt;/li&gt;
  &lt;li&gt;Fix CORS issues when downloading document&lt;/li&gt;
  &lt;li&gt;Implementation of case-handling with registryEntry and document upload&lt;/li&gt;
  &lt;li&gt;Better support in Javascript for OPTIONS&lt;/li&gt;
  &lt;li&gt;Adding concept description of mail integration&lt;/li&gt;
  &lt;li&gt;Improve setting of default values for GET on ny-journalpost&lt;/li&gt;
  &lt;li&gt;Better handling of required values during deserialisation &lt;/li&gt;
  &lt;li&gt;Changed tilknyttetDato (M620) from date to dateTime&lt;/li&gt;
  &lt;li&gt;Corrected some opprettetDato (M600) (de)serialisation errors.&lt;/li&gt;
  &lt;li&gt;Improve parse error reporting.&lt;/li&gt;
  &lt;li&gt;Started on OData search and filtering.&lt;/li&gt;
  &lt;li&gt;Added Contributor Covenant Code of Conduct to project.&lt;/li&gt;
  &lt;li&gt;Moved repository and project from Github to Gitlab.&lt;/li&gt;
  &lt;li&gt;Restructured repository, moved code into src/ and web/.&lt;/li&gt;
  &lt;li&gt;Updated code to use Spring Boot version 2.&lt;/li&gt;
  &lt;li&gt;Added support for OAuth2 authentication.&lt;/li&gt;
  &lt;li&gt;Fixed several bugs discovered by Coverity.&lt;/li&gt;
  &lt;li&gt;Corrected handling of date/datetime fields.&lt;/li&gt;
  &lt;li&gt;Improved error reporting when rejecting during deserializatoin.&lt;/li&gt;
  &lt;li&gt;Adjusted default values provided for ny-arkivdel, ny-mappe,
   ny-saksmappe, ny-journalpost and ny-dokumentbeskrivelse.&lt;/li&gt;
  &lt;li&gt;Several fixes for korrespondansepart*.&lt;/li&gt;
  &lt;li&gt;Updated web GUI:
     &lt;ul&gt;
       &lt;li&gt;Now handle both file upload and download.&lt;/li&gt;
       &lt;li&gt;Uses new OAuth2 authentication for login.&lt;/li&gt;
       &lt;li&gt;Forms now fetches default values from API using GET.&lt;/li&gt;
       &lt;li&gt;Added RFC 822 (email), TIFF and JPEG to list of possible file formats.&lt;/li&gt;
     &lt;/ul&gt;&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;The changes and improvements are extensive.  Running diffstat on
the changes between git tab 0.1.1 and 0.2 show 1098 files changed,
108666 insertions(+), 54066 deletions(-).&lt;/p&gt;

&lt;p&gt;If free and open standardized archiving API sound interesting to
you, please contact us on IRC
(&lt;a href=&quot;irc://irc.freenode.net/%23nikita&quot;&gt;#nikita on
irc.freenode.net&lt;/a&gt;) or email
(&lt;a href=&quot;https://lists.nuug.no/mailman/listinfo/nikita-noark&quot;&gt;nikita-noark
mailing list&lt;/a&gt;).&lt;/p&gt;

&lt;p&gt;As usual, if you use Bitcoin and want to show your support of my
activities, please send Bitcoin donations to my address
&lt;b&gt;&lt;a href=&quot;bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b&quot;&gt;15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b&lt;/a&gt;&lt;/b&gt;.&lt;/p&gt;
</description>
        </item>
        
        <item>
                <title>Fetching trusted timestamps using the rfc3161ng python module</title>
                <link>http://people.skolelinux.org/pere/blog/Fetching_trusted_timestamps_using_the_rfc3161ng_python_module.html</link>
                <guid isPermaLink="true">http://people.skolelinux.org/pere/blog/Fetching_trusted_timestamps_using_the_rfc3161ng_python_module.html</guid>
                <pubDate>Mon, 8 Oct 2018 12:30:00 +0200</pubDate>
                <description>&lt;p&gt;I have  earlier covered the basics of trusted timestamping using the
&#39;openssl ts&#39; client.  See blog post for
&lt;a href=&quot;http://people.skolelinux.org/pere/blog/Public_Trusted_Timestamping_services_for_everyone.html&quot;&gt;2014&lt;/a&gt;,
&lt;a href=&quot;http://people.skolelinux.org/pere/blog/syslog_trusted_timestamp___chain_of_trusted_timestamps_for_your_syslog.html&quot;&gt;2016&lt;/a&gt;
and
&lt;a href=&quot;http://people.skolelinux.org/pere/blog/Idea_for_storing_trusted_timestamps_in_a_Noark_5_archive.html&quot;&gt;2017&lt;/a&gt;
for those stories.  But some times I want to integrate the timestamping
in other code, and recently I needed to integrate it into Python.
After searching a bit, I found
&lt;a href=&quot;https://dev.entrouvert.org/projects/python-rfc3161&quot;&gt;the
rfc3161 library&lt;/a&gt; which seemed like a good fit, but I soon
discovered it only worked for python version 2, and I needed something
that work with python version 3.  Luckily I next came across
&lt;a href=&quot;https://github.com/trbs/rfc3161ng/&quot;&gt;the rfc3161ng library&lt;/a&gt;,
a fork of the original rfc3161 library.  Not only is it working with
python 3, it have fixed a few of the bugs in the original library, and
it has an active maintainer.  I decided to wrap it up and make it
&lt;a href=&quot;https://tracker.debian.org/pkg/python-rfc3161ng&quot;&gt;available in
Debian&lt;/a&gt;, and a few days ago it entered Debian unstable and testing.&lt;/p&gt;

&lt;p&gt;Using the library is fairly straight forward.  The only slightly
problematic step is to fetch the required certificates to verify the
timestamp.  For some services it is straight forward, while for others
I have not yet figured out how to do it.  Here is a small standalone
code example based on of the integration tests in the library code:&lt;/p&gt;

&lt;pre&gt;
#!/usr/bin/python3

&quot;&quot;&quot;

Python 3 script demonstrating how to use the rfc3161ng module to
get trusted timestamps.

The license of this code is the same as the license of the rfc3161ng
library, ie MIT/BSD.

&quot;&quot;&quot;

import os
import pyasn1.codec.der
import rfc3161ng
import subprocess
import tempfile
import urllib.request

def store(f, data):
    f.write(data)
    f.flush()
    f.seek(0)

def fetch(url, f=None):
    response = urllib.request.urlopen(url)
    data = response.read()
    if f:
        store(f, data)
    return data

def main():
    with tempfile.NamedTemporaryFile() as cert_f,\
         tempfile.NamedTemporaryFile() as ca_f,\
         tempfile.NamedTemporaryFile() as msg_f,\
         tempfile.NamedTemporaryFile() as tsr_f:

        # First fetch certificates used by service
        certificate_data = fetch(&#39;https://freetsa.org/files/tsa.crt&#39;, cert_f)
        ca_data_data = fetch(&#39;https://freetsa.org/files/cacert.pem&#39;, ca_f)

        # Then timestamp the message
        timestamper = \
            rfc3161ng.RemoteTimestamper(&#39;http://freetsa.org/tsr&#39;,
                                        certificate=certificate_data)
        data = b&quot;Python forever!\n&quot;
        tsr = timestamper(data=data, return_tsr=True)

        # Finally, convert message and response to something &#39;openssl ts&#39; can verify
        store(msg_f, data)
        store(tsr_f, pyasn1.codec.der.encoder.encode(tsr))
        args = [&quot;openssl&quot;, &quot;ts&quot;, &quot;-verify&quot;,
                &quot;-data&quot;, msg_f.name,
                &quot;-in&quot;, tsr_f.name,
                &quot;-CAfile&quot;, ca_f.name,
                &quot;-untrusted&quot;, cert_f.name]
        subprocess.check_call(args)

if &#39;__main__&#39; == __name__:
   main()
&lt;/pre&gt;

&lt;p&gt;The code fetches the required certificates, store them as temporary
files, timestamp a simple message, store the message and timestamp to
disk and ask &#39;openssl ts&#39; to verify the timestamp.  A timestamp is
around 1.5 kiB in size, and should be fairly easy to store for future
use.&lt;/p&gt;

&lt;p&gt;As usual, if you use Bitcoin and want to show your support of my
activities, please send Bitcoin donations to my address
&lt;b&gt;&lt;a href=&quot;bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b&quot;&gt;15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b&lt;/a&gt;&lt;/b&gt;.&lt;/p&gt;
</description>
        </item>
        
        <item>
                <title>Automatic Google Drive sync using grive in Debian</title>
                <link>http://people.skolelinux.org/pere/blog/Automatic_Google_Drive_sync_using_grive_in_Debian.html</link>
                <guid isPermaLink="true">http://people.skolelinux.org/pere/blog/Automatic_Google_Drive_sync_using_grive_in_Debian.html</guid>
                <pubDate>Thu, 4 Oct 2018 15:20:00 +0200</pubDate>
                <description>&lt;p&gt;A few days, I rescued a Windows victim over to Debian.  To try to
rescue the remains, I helped set up automatic sync with Google Drive.
I did not find any sensible Debian package handling this
automatically, so I rebuild the grive2 source from
&lt;a href=&quot;http://www.webupd8.org/&quot;&gt;the Ubuntu UPD8 PPA&lt;/a&gt; to do the
task and added a autostart desktop entry and a small shell script to
run in the background while the user is logged in to do the sync.
Here is a sketch of the setup for future reference.&lt;/p&gt;

&lt;p&gt;I first created &lt;tt&gt;~/googledrive&lt;/tt&gt;, entered the directory and
ran &#39;&lt;tt&gt;grive -a&lt;/tt&gt;&#39; to authenticate the machine/user.  Next, I
created a autostart hook in &lt;tt&gt;~/.config/autostart/grive.desktop&lt;/tt&gt;
to start the sync when the user log in:&lt;/p&gt;

&lt;p&gt;&lt;blockquote&gt;&lt;pre&gt;
[Desktop Entry]
Name=Google drive autosync
Type=Application
Exec=/home/user/bin/grive-sync
&lt;/pre&gt;&lt;/blockquote&gt;&lt;/p&gt;

&lt;p&gt;Finally, I wrote the &lt;tt&gt;~/bin/grive-sync&lt;/tt&gt; script to sync
~/googledrive/ with the files in Google Drive.&lt;/p&gt;

&lt;p&gt;&lt;blockquote&gt;&lt;pre&gt;
#!/bin/sh
set -e
cd ~/
cleanup() {
    if [ &quot;$syncpid&quot; ] ; then
        kill $syncpid
    fi
}
trap cleanup EXIT INT QUIT
/usr/lib/grive/grive-sync.sh listen googledrive 2&gt;&amp;1 | sed &quot;s%^%$0:%&quot; &amp;
syncpdi=$!
while true; do
    if ! xhost &gt;/dev/null 2&gt;&amp;1 ; then
        echo &quot;no DISPLAY, exiting as the user probably logged out&quot;
        exit 1
    fi
    if [ ! -e /run/user/1000/grive-sync.sh_googledrive ] ; then
        /usr/lib/grive/grive-sync.sh sync googledrive
    fi
    sleep 300
done 2&gt;&amp;1 | sed &quot;s%^%$0:%&quot;
&lt;/pre&gt;&lt;/blockquote&gt;&lt;/p&gt;

&lt;p&gt;Feel free to use the setup if you want.  It can be assumed to be
GNU GPL v2 licensed (or any later version, at your leisure), but I
doubt this code is possible to claim copyright on.&lt;/p&gt;

&lt;p&gt;As usual, if you use Bitcoin and want to show your support of my
activities, please send Bitcoin donations to my address
&lt;b&gt;&lt;a href=&quot;bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b&quot;&gt;15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b&lt;/a&gt;&lt;/b&gt;.&lt;/p&gt;
</description>
        </item>
        
        <item>
                <title>Valutakrambod - A python and bitcoin love story</title>
                <link>http://people.skolelinux.org/pere/blog/Valutakrambod___A_python_and_bitcoin_love_story.html</link>
                <guid isPermaLink="true">http://people.skolelinux.org/pere/blog/Valutakrambod___A_python_and_bitcoin_love_story.html</guid>
                <pubDate>Sat, 29 Sep 2018 22:20:00 +0200</pubDate>
                <description>&lt;p&gt;It would come as no surprise to anyone that I am interested in
bitcoins and virtual currencies.  I&#39;ve been keeping an eye on virtual
currencies for many years, and it is part of the reason a few months
ago, I started writing a python library for collecting currency
exchange rates and trade on virtual currency exchanges.  I decided to
name the end result valutakrambod, which perhaps can be translated to
small currency shop.&lt;/p&gt;

&lt;p&gt;The library uses the tornado python library to handle HTTP and
websocket connections, and provide a asynchronous system for
connecting to and tracking several services.  The code is available
from
&lt;a href=&quot;http://github.com/petterreinholdtsen/valutakrambod&quot;&gt;github&lt;/a&gt;.&lt;/p&gt;

&lt;/p&gt;There are two example clients of the library.  One is very simple and
list every updated buy/sell price received from the various services.
This code is started by running bin/btc-rates and call the client code
in valutakrambod/client.py.  The simple client look like this:&lt;/p&gt;

&lt;p&gt;&lt;blockquote&gt;&lt;pre&gt;
import functools
import tornado.ioloop
import valutakrambod
class SimpleClient(object):
    def __init__(self):
        self.services = []
        self.streams = []
        pass
    def newdata(self, service, pair, changed):
        print(&quot;%-15s %s-%s: %8.3f %8.3f&quot; % (
            service.servicename(),
            pair[0],
            pair[1],
            service.rates[pair][&#39;ask&#39;],
            service.rates[pair][&#39;bid&#39;])
        )
    async def refresh(self, service):
        await service.fetchRates(service.wantedpairs)
    def run(self):
        self.ioloop = tornado.ioloop.IOLoop.current()
        self.services = valutakrambod.service.knownServices()
        for e in self.services:
            service = e()
            service.subscribe(self.newdata)
            stream = service.websocket()
            if stream:
                self.streams.append(stream)
            else:
                # Fetch information from non-streaming services immediately
                self.ioloop.call_later(len(self.services),
                                       functools.partial(self.refresh, service))
                # as well as regularly
                service.periodicUpdate(60)
        for stream in self.streams:
            stream.connect()
        try:
            self.ioloop.start()
        except KeyboardInterrupt:
            print(&quot;Interrupted by keyboard, closing all connections.&quot;)
            pass
        for stream in self.streams:
            stream.close()
&lt;/pre&gt;&lt;/blockquote&gt;&lt;/p&gt;

&lt;p&gt;The library client loops over all known &quot;public&quot; services,
initialises it, subscribes to any updates from the service, checks and
activates websocket streaming if the service provide it, and if no
streaming is supported, fetches information from the service and sets
up a periodic update every 60 seconds.  The output from this client
can look like this:&lt;/p&gt;

&lt;p&gt;&lt;blockquote&gt;&lt;pre&gt;
Bl3p            BTC-EUR: 5687.110 5653.690
Bl3p            BTC-EUR: 5687.110 5653.690
Bl3p            BTC-EUR: 5687.110 5653.690
Hitbtc          BTC-USD: 6594.560 6593.690
Hitbtc          BTC-USD: 6594.560 6593.690
Bl3p            BTC-EUR: 5687.110 5653.690
Hitbtc          BTC-USD: 6594.570 6593.690
Bitstamp        EUR-USD:    1.159    1.154
Hitbtc          BTC-USD: 6594.570 6593.690
Hitbtc          BTC-USD: 6594.580 6593.690
Hitbtc          BTC-USD: 6594.580 6593.690
Hitbtc          BTC-USD: 6594.580 6593.690
Bl3p            BTC-EUR: 5687.110 5653.690
Paymium         BTC-EUR: 5680.000 5620.240
&lt;/pre&gt;&lt;/blockquote&gt;&lt;/p&gt;

&lt;p&gt;The exchange order book is tracked in addition to the best buy/sell
price, for those that need to know the details.&lt;/p&gt;

&lt;p&gt;The other example client is focusing on providing a curses view
with updated buy/sell prices as soon as they are received from the
services.  This code is located in bin/btc-rates-curses and activated
by using the &#39;-c&#39; argument.  Without the argument the &quot;curses&quot; output
is printed without using curses, which is useful for debugging.  The
curses view look like this:&lt;/p&gt;

&lt;p&gt;&lt;blockquote&gt;&lt;pre&gt;
           Name Pair   Bid         Ask         Spr    Ftcd    Age
 BitcoinsNorway BTCEUR   5591.8400   5711.0800   2.1%   16    nan     60
       Bitfinex BTCEUR   5671.0000   5671.2000   0.0%   16     22     59
        Bitmynt BTCEUR   5580.8000   5807.5200   3.9%   16     41     60
         Bitpay BTCEUR   5663.2700         nan   nan%   15    nan     60
       Bitstamp BTCEUR   5664.8400   5676.5300   0.2%    0      1      1
           Bl3p BTCEUR   5653.6900   5684.9400   0.5%    0    nan     19
       Coinbase BTCEUR   5600.8200   5714.9000   2.0%   15    nan    nan
         Kraken BTCEUR   5670.1000   5670.2000   0.0%   14     17     60
        Paymium BTCEUR   5620.0600   5680.0000   1.1%    1   7515    nan
 BitcoinsNorway BTCNOK  52898.9700  54034.6100   2.1%   16    nan     60
        Bitmynt BTCNOK  52960.3200  54031.1900   2.0%   16     41     60
         Bitpay BTCNOK  53477.7833         nan   nan%   16    nan     60
       Coinbase BTCNOK  52990.3500  54063.0600   2.0%   15    nan    nan
        MiraiEx BTCNOK  52856.5300  54100.6000   2.3%   16    nan    nan
 BitcoinsNorway BTCUSD   6495.5300   6631.5400   2.1%   16    nan     60
       Bitfinex BTCUSD   6590.6000   6590.7000   0.0%   16     23     57
         Bitpay BTCUSD   6564.1300         nan   nan%   15    nan     60
       Bitstamp BTCUSD   6561.1400   6565.6200   0.1%    0      2      1
       Coinbase BTCUSD   6504.0600   6635.9700   2.0%   14    nan    117
         Gemini BTCUSD   6567.1300   6573.0700   0.1%   16     89    nan
         Hitbtc+BTCUSD   6592.6200   6594.2100   0.0%    0      0      0
         Kraken BTCUSD   6565.2000   6570.9000   0.1%   15     17     58
  Exchangerates EURNOK      9.4665      9.4665   0.0%   16 107789    nan
     Norgesbank EURNOK      9.4665      9.4665   0.0%   16 107789    nan
       Bitstamp EURUSD      1.1537      1.1593   0.5%    4      5      1
  Exchangerates EURUSD      1.1576      1.1576   0.0%   16 107789    nan
 BitcoinsNorway LTCEUR      1.0000     49.0000  98.0%   16    nan    nan
 BitcoinsNorway LTCNOK    492.4800    503.7500   2.2%   16    nan     60
 BitcoinsNorway LTCUSD      1.0221     49.0000  97.9%   15    nan    nan
     Norgesbank USDNOK      8.1777      8.1777   0.0%   16 107789    nan
&lt;/pre&gt;&lt;/blockquote&gt;&lt;/p&gt;

&lt;p&gt;The code for this client is too complex for a simple blog post, so
you will have to check out the git repository to figure out how it
work.  What I can tell is how the three last numbers on each line
should be interpreted.  The first is how many seconds ago information
was received from the service.  The second is how long ago, according
to the service, the provided information was updated.  The last is an
estimate on how often the buy/sell values change.&lt;/p&gt;

&lt;p&gt;If you find this library useful, or would like to improve it, I
would love to hear from you.  Note that for some of the services I&#39;ve
implemented a trading API.  It might be the topic of a future blog
post.&lt;/p&gt;

&lt;p&gt;As usual, if you use Bitcoin and want to show your support of my
activities, please send Bitcoin donations to my address
&lt;b&gt;&lt;a href=&quot;bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b&quot;&gt;15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b&lt;/a&gt;&lt;/b&gt;.&lt;/p&gt;
</description>
        </item>
        
        <item>
                <title>VLC in Debian now can do bittorrent streaming</title>
                <link>http://people.skolelinux.org/pere/blog/VLC_in_Debian_now_can_do_bittorrent_streaming.html</link>
                <guid isPermaLink="true">http://people.skolelinux.org/pere/blog/VLC_in_Debian_now_can_do_bittorrent_streaming.html</guid>
                <pubDate>Mon, 24 Sep 2018 21:20:00 +0200</pubDate>
                <description>&lt;p&gt;Back in February, I got curious to see
&lt;a href=&quot;http://people.skolelinux.org/pere/blog/Using_VLC_to_stream_bittorrent_sources.html&quot;&gt;if
VLC now supported Bittorrent streaming&lt;/a&gt;.  It did not, despite the
fact that the idea and code to handle such streaming had been floating
around for years.  I did however find
&lt;a href=&quot;https://github.com/johang/vlc-bittorrent&quot;&gt;a standalone plugin
for VLC&lt;/a&gt; to do it, and half a year later I decided to wrap up the
plugin and get it into Debian.  I uploaded it to NEW a few days ago,
and am very happy to report that it
&lt;a href=&quot;https://tracker.debian.org/pkg/vlc-plugin-bittorrent&quot;&gt;entered
Debian&lt;/a&gt; a few hours ago, and should be available in Debian/Unstable
tomorrow, and Debian/Testing in a few days.&lt;/p&gt;

&lt;p&gt;With the vlc-plugin-bittorrent package installed you should be able
to stream videos using a simple call to&lt;/p&gt;

&lt;p&gt;&lt;blockquote&gt;&lt;pre&gt;
vlc https://archive.org/download/TheGoat/TheGoat_archive.torrent
&lt;/pre&gt;&lt;/blockquote&gt;&lt;/p&gt;

&lt;/p&gt;It can handle magnet links too.  Now if only native vlc had
bittorrent support.  Then a lot more would be helping each other to
share public domain and creative commons movies.  The plugin need some
stability work with seeking and picking the right file in a torrent
with many files, but is already usable.  Please note that the plugin
is not removing downloaded files when vlc is stopped, so it can fill
up your disk if you are not careful.  Have fun. :)&lt;/p&gt;

&lt;p&gt;I would love to get help maintaining this package.  Get in touch if
you are interested.&lt;/p&gt;

&lt;p&gt;As usual, if you use Bitcoin and want to show your support of my
activities, please send Bitcoin donations to my address
&lt;b&gt;&lt;a href=&quot;bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b&quot;&gt;15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b&lt;/a&gt;&lt;/b&gt;.&lt;/p&gt;
</description>
        </item>
        
        <item>
                <title>Using the Kodi API to play Youtube videos</title>
                <link>http://people.skolelinux.org/pere/blog/Using_the_Kodi_API_to_play_Youtube_videos.html</link>
                <guid isPermaLink="true">http://people.skolelinux.org/pere/blog/Using_the_Kodi_API_to_play_Youtube_videos.html</guid>
                <pubDate>Sun, 2 Sep 2018 23:40:00 +0200</pubDate>
                <description>&lt;p&gt;I continue to explore my Kodi installation, and today I wanted to
tell it to play a youtube URL I received in a chat, without having to
insert search terms using the on-screen keyboard.  After searching the
web for API access to the Youtube plugin and testing a bit, I managed
to find a recipe that worked.  If you got a kodi instance with its API
available from http://kodihost/jsonrpc, you can try the following to
have check out a nice cover band.&lt;/p&gt;

&lt;p&gt;&lt;blockquote&gt;&lt;pre&gt;curl --silent --header &#39;Content-Type: application/json&#39; \
  --data-binary &#39;{ &quot;id&quot;: 1, &quot;jsonrpc&quot;: &quot;2.0&quot;, &quot;method&quot;: &quot;Player.Open&quot;,
  &quot;params&quot;: {&quot;item&quot;: { &quot;file&quot;:
  &quot;plugin://plugin.video.youtube/play/?video_id=LuRGVM9O0qg&quot; } } }&#39; \
  http://projector.local/jsonrpc&lt;/pre&gt;&lt;/blockquote&gt;&lt;/p&gt;

&lt;p&gt;I&#39;ve extended kodi-stream program to take a video source as its
first argument.  It can now handle direct video links, youtube links
and &#39;desktop&#39; to stream my desktop to Kodi.  It is almost like a
Chromecast. :)&lt;/p&gt;

&lt;p&gt;As usual, if you use Bitcoin and want to show your support of my
activities, please send Bitcoin donations to my address
&lt;b&gt;&lt;a href=&quot;bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b&quot;&gt;15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b&lt;/a&gt;&lt;/b&gt;.&lt;/p&gt;
</description>
        </item>
        
        <item>
                <title>Software created using taxpayers’ money should be Free Software</title>
                <link>http://people.skolelinux.org/pere/blog/Software_created_using_taxpayers__money_should_be_Free_Software.html</link>
                <guid isPermaLink="true">http://people.skolelinux.org/pere/blog/Software_created_using_taxpayers__money_should_be_Free_Software.html</guid>
                <pubDate>Thu, 30 Aug 2018 13:50:00 +0200</pubDate>
                <description>&lt;p&gt;It might seem obvious that software created using tax money should
be available for everyone to use and improve.  Free Software
Foundation Europe recentlystarted a campaign to help get more people
to understand this, and I just signed the petition on
&lt;a href=&quot;https://publiccode.eu/&quot;&gt;Public Money, Public Code&lt;/a&gt; to help
them. I hope you too will do the same.&lt;/p&gt;
</description>
        </item>
        
        <item>
                <title>A bit more on privacy respecting health monitor / fitness tracker</title>
                <link>http://people.skolelinux.org/pere/blog/A_bit_more_on_privacy_respecting_health_monitor___fitness_tracker.html</link>
                <guid isPermaLink="true">http://people.skolelinux.org/pere/blog/A_bit_more_on_privacy_respecting_health_monitor___fitness_tracker.html</guid>
                <pubDate>Mon, 13 Aug 2018 09:00:00 +0200</pubDate>
                <description>&lt;p&gt;A few days ago, I wondered if there are any privacy respecting
health monitors and/or fitness trackers available for sale these days.
I would like to buy one, but do not want to share my personal data
with strangers, nor be forced to have a mobile phone to get data out
of the unit.  I&#39;ve received some ideas, and would like to share them
with you.

One interesting data point was a pointer to a Free Software app for
Android named
&lt;a href=&quot;https://github.com/Freeyourgadget/Gadgetbridge/&quot;&gt;Gadgetbridge&lt;/a&gt;.
It provide cloudless collection and storing of data from a variety of
trackers.  Its
&lt;a href=&quot;https://github.com/Freeyourgadget/Gadgetbridge/#supported-devices&quot;&gt;list
of supported devices&lt;/a&gt; is a good indicator for units where the
protocol is fairly open, as it is obviously being handled by Free
Software.  Other units are reportedly encrypting the collected
information with their own public key, making sure only the vendor
cloud service is able to extract data from the unit.  The people
contacting me about Gadgetbirde said they were using
&lt;a href=&quot;https://us.amazfit.com/shop/bip?variant=336750&quot;&gt;Amazfit
Bip&lt;/a&gt; and
&lt;a href=&quot;http://www.xiaomimi6phone.com/xiaomi-mi-band-3-features-release-date-rumors/&quot;&gt;Xiaomi
Band 3&lt;/a&gt;.&lt;/p&gt;

&lt;p&gt;I also got a suggestion to look at some of the units from Garmin.
I was told their GPS watches can be connected via USB and show up as a
USB storage device with
&lt;a href=&quot;https://www.gpsbabel.org/htmldoc-development/fmt_garmin_fit.html&quot;&gt;Garmin
FIT files&lt;/a&gt; containing the collected measurements.  While
proprietary, FIT files apparently can be read at least by
&lt;a href=&quot;https://www.gpsbabel.org&quot;&gt;GPSBabel&lt;/a&gt; and the
&lt;a href=&quot;https://apps.nextcloud.com/apps/gpxpod&quot;&gt;GpxPod&lt;/a&gt; Nextcloud
app.  It is unclear to me if they can read step count and heart rate
data.  The person I talked to was using a
&lt;a href=&quot;https://buy.garmin.com/en-US/US/p/564291&quot;&gt;Garmin Forerunner
935&lt;/a&gt;, which is a fairly expensive unit.  I doubt it is worth it for
a unit where the vendor clearly is trying its best to move from open
to closed systems.  I still remember when Garmin dropped NMEA support
in its GPSes.&lt;/p&gt;

&lt;p&gt;A final idea was to build ones own unit, perhaps by basing it on a
wearable hardware platforms like
&lt;a href=&quot;https://learn.adafruit.com/flora-geo-watch&quot;&gt;the Flora Geo
Watch&lt;/a&gt;.  Sound like fun, but I had more money than time to spend on
the topic, so I suspect it will have to wait for another time.&lt;/p&gt;

&lt;p&gt;While I was working on tracking down links, I came across an
inspiring TED talk by Dave Debronkart about
&lt;a href=&quot;https://archive.org/details/DavedeBronkart_2010X&quot;&gt;being a
e-patient&lt;/a&gt;, and discovered the web site
&lt;a href=&quot;https://participatorymedicine.org/epatients/&quot;&gt;Participatory
Medicine&lt;/a&gt;.  If you too want to track your own health and fitness
without having information about your private life floating around on
computers owned by others, I recommend checking it out.&lt;/p&gt;

&lt;p&gt;As usual, if you use Bitcoin and want to show your support of my
activities, please send Bitcoin donations to my address
&lt;b&gt;&lt;a href=&quot;bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b&quot;&gt;15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b&lt;/a&gt;&lt;/b&gt;.&lt;/p&gt;
</description>
        </item>
        
        </channel>
</rss>