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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>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 loop over all known &quot;public&quot; services,
initialises it, subscribe to any updates from the service, check and
activate websocket streaming if the service provide it, and if no
streaming is supported, fetch information from the service and set 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>
        
        <item>
                <title>Privacy respecting health monitor / fitness tracker?</title>
                <link>http://people.skolelinux.org/pere/blog/Privacy_respecting_health_monitor___fitness_tracker_.html</link>
                <guid isPermaLink="true">http://people.skolelinux.org/pere/blog/Privacy_respecting_health_monitor___fitness_tracker_.html</guid>
                <pubDate>Tue, 7 Aug 2018 16:00:00 +0200</pubDate>
                <description>&lt;p&gt;Dear lazyweb,&lt;/p&gt;

&lt;p&gt;I wonder, is there a fitness tracker / health monitor available for
sale today that respect the users privacy?  With this I mean a
watch/bracelet capable of measuring pulse rate and other
fitness/health related values (and by all means, also the correct time
and location if possible), which is &lt;strong&gt;only&lt;/strong&gt; provided for
me to extract/read from the unit with computer without a radio beacon
and Internet connection.  In other words, it do not depend on a cell
phone app, and do make the measurements available via other peoples
computer (aka &quot;the cloud&quot;).  The collected data should be available
using only free software.  I&#39;m not interested in depending on some
non-free software that will leave me high and dry some time in the
future.  I&#39;ve been unable to find any such unit.  I would like to buy
it.  The ones I have seen for sale here in Norway are proud to report
that they share my health data with strangers (aka &quot;cloud enabled&quot;).
Is there an alternative?  I&#39;m not interested in giving money to people
requiring me to accept &quot;privacy terms&quot; to allow myself to measure my
own health.&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>Sharing images with friends and family using RSS and EXIF/XMP metadata</title>
                <link>http://people.skolelinux.org/pere/blog/Sharing_images_with_friends_and_family_using_RSS_and_EXIF_XMP_metadata.html</link>
                <guid isPermaLink="true">http://people.skolelinux.org/pere/blog/Sharing_images_with_friends_and_family_using_RSS_and_EXIF_XMP_metadata.html</guid>
                <pubDate>Tue, 31 Jul 2018 23:30:00 +0200</pubDate>
                <description>&lt;p&gt;For a while now, I have looked for a sensible way to share images
with my family using a self hosted solution, as it is unacceptable to
place images from my personal life under the control of strangers
working for data hoarders like Google or Dropbox.  The last few days I
have drafted an approach that might work out, and I would like to
share it with you.  I would like to publish images on a server under
my control, and point some Internet connected display units using some
free and open standard to the images I published.  As my primary
language is not limited to ASCII, I need to store metadata using
UTF-8.  Many years ago, I hoped to find a digital photo frame capable
of reading a RSS feed with image references (aka using the
&amp;lt;enclosure&amp;gt; RSS tag), but was unable to find a current supplier
of such frames.  In the end I gave up that approach.&lt;/p&gt;

&lt;p&gt;Some months ago, I discovered that
&lt;a href=&quot;https://www.jwz.org/xscreensaver/&quot;&gt;XScreensaver&lt;/a&gt; is able to
read images from a RSS feed, and used it to set up a screen saver on
my home info screen, showing images from the Daily images feed from
NASA.  This proved to work well.  More recently I discovered that
&lt;a href=&quot;https://kodi.tv&quot;&gt;Kodi&lt;/a&gt; (both using
&lt;a href=&quot;https://www.openelec.tv/&quot;&gt;OpenELEC&lt;/a&gt; and
&lt;a href=&quot;https://libreelec.tv&quot;&gt;LibreELEC&lt;/a&gt;) provide the
&lt;a href=&quot;https://github.com/grinsted/script.screensaver.feedreader&quot;&gt;Feedreader&lt;/a&gt;
screen saver capable of reading a RSS feed with images and news.  For
fun, I used it this summer to test Kodi on my parents TV by hooking up
a Raspberry PI unit with LibreELEC, and wanted to provide them with a
screen saver showing selected pictures from my selection.&lt;/p&gt;

&lt;p&gt;Armed with motivation and a test photo frame, I set out to generate
a RSS feed for the Kodi instance.  I adjusted my &lt;a
href=&quot;https://freedombox.org/&quot;&gt;Freedombox&lt;/a&gt; instance, created
/var/www/html/privatepictures/, wrote a small Perl script to extract
title and description metadata from the photo files and generate the
RSS file.  I ended up using Perl instead of python, as the
libimage-exiftool-perl Debian package seemed to handle the EXIF/XMP
tags I ended up using, while python3-exif did not.  The relevant EXIF
tags only support ASCII, so I had to find better alternatives.  XMP
seem to have the support I need.&lt;/p&gt;

&lt;p&gt;I am a bit unsure which EXIF/XMP tags to use, as I would like to
use tags that can be easily added/updated using normal free software
photo managing software.  I ended up using the tags set using this
exiftool command, as these tags can also be set using digiKam:&lt;/p&gt;

&lt;blockquote&gt;&lt;pre&gt;
exiftool -headline=&#39;The RSS image title&#39; \
  -description=&#39;The RSS image description.&#39; \
  -subject+=for-family photo.jpeg
&lt;/pre&gt;&lt;/blockquote&gt;

&lt;p&gt;I initially tried the &quot;-title&quot; and &quot;keyword&quot; tags, but they were
invisible in digiKam, so I changed to &quot;-headline&quot; and &quot;-subject&quot;.  I
use the keyword/subject &#39;for-family&#39; to flag that the photo should be
shared with my family.  Images with this keyword set are located and
copied into my Freedombox for the RSS generating script to find.&lt;/p&gt;

&lt;p&gt;Are there better ways to do this?  Get in touch if you have better
suggestions.&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>Simple streaming the Linux desktop to Kodi using GStreamer and RTP</title>
                <link>http://people.skolelinux.org/pere/blog/Simple_streaming_the_Linux_desktop_to_Kodi_using_GStreamer_and_RTP.html</link>
                <guid isPermaLink="true">http://people.skolelinux.org/pere/blog/Simple_streaming_the_Linux_desktop_to_Kodi_using_GStreamer_and_RTP.html</guid>
                <pubDate>Thu, 12 Jul 2018 17:55:00 +0200</pubDate>
                <description>&lt;p&gt;Last night, I wrote
&lt;a href=&quot;http://people.skolelinux.org/pere/blog/Streaming_the_Linux_desktop_to_Kodi_using_VLC_and_RTSP.html&quot;&gt;a
recipe to stream a Linux desktop using VLC to a instance of Kodi&lt;/a&gt;.
During the day I received valuable feedback, and thanks to the
suggestions I have been able to rewrite the recipe into a much simpler
approach requiring no setup at all.  It is a single script that take
care of it all.&lt;/p&gt;

&lt;p&gt;This new script uses GStreamer instead of VLC to capture the
desktop and stream it to Kodi.  This fixed the video quality issue I
saw initially.  It further removes the need to add a m3u file on the
Kodi machine, as it instead connects to
&lt;a href=&quot;https://kodi.wiki/view/JSON-RPC_API/v8&quot;&gt;the JSON-RPC API in
Kodi&lt;/a&gt; and simply ask Kodi to play from the stream created using
GStreamer.  Streaming the desktop to Kodi now become trivial.  Copy
the script below, run it with the DNS name or IP address of the kodi
server to stream to as the only argument, and watch your screen show
up on the Kodi screen.  Note, it depend on multicast on the local
network, so if you need to stream outside the local network, the
script must be modified.  Also note, I have no idea if audio work, as
I only care about the picture part.&lt;/p&gt;

&lt;blockquote&gt;&lt;pre&gt;
#!/bin/sh
#
# Stream the Linux desktop view to Kodi.  See
# http://people.skolelinux.org/pere/blog/Streaming_the_Linux_desktop_to_Kodi_using_VLC_and_RTSP.html
# for backgorund information.

# Make sure the stream is stopped in Kodi and the gstreamer process is
# killed if something go wrong (for example if curl is unable to find the
# kodi server).  Do the same when interrupting this script.
kodicmd() {
    host=&quot;$1&quot;
    cmd=&quot;$2&quot;
    params=&quot;$3&quot;
    curl --silent --header &#39;Content-Type: application/json&#39; \
         --data-binary &quot;{ \&quot;id\&quot;: 1, \&quot;jsonrpc\&quot;: \&quot;2.0\&quot;, \&quot;method\&quot;: \&quot;$cmd\&quot;, \&quot;params\&quot;: $params }&quot; \
         &quot;http://$host/jsonrpc&quot;
}
cleanup() {
    if [ -n &quot;$kodihost&quot; ] ; then
        # Stop the playing when we end
        playerid=$(kodicmd &quot;$kodihost&quot; Player.GetActivePlayers &quot;{}&quot; |
                            jq .result[].playerid)
        kodicmd &quot;$kodihost&quot; Player.Stop &quot;{ \&quot;playerid\&quot; : $playerid }&quot; &gt; /dev/null
    fi
    if [ &quot;$gstpid&quot; ] &amp;&amp; kill -0 &quot;$gstpid&quot; &gt;/dev/null 2&gt;&amp;1; then
        kill &quot;$gstpid&quot;
    fi
}
trap cleanup EXIT INT

if [ -n &quot;$1&quot; ]; then
    kodihost=$1
    shift
else
    kodihost=kodi.local
fi

mcast=239.255.0.1
mcastport=1234
mcastttl=1

pasrc=$(pactl list | grep -A2 &#39;Source #&#39; | grep &#39;Name: .*\.monitor$&#39; | \
  cut -d&quot; &quot; -f2|head -1)
gst-launch-1.0 ximagesrc use-damage=0 ! video/x-raw,framerate=30/1 ! \
  videoconvert ! queue2 ! \
  x264enc bitrate=8000 speed-preset=superfast tune=zerolatency qp-min=30 \
  key-int-max=15 bframes=2 ! video/x-h264,profile=high ! queue2 ! \
  mpegtsmux alignment=7 name=mux ! rndbuffersize max=1316 min=1316 ! \
  udpsink host=$mcast port=$mcastport ttl-mc=$mcastttl auto-multicast=1 sync=0 \
  pulsesrc device=$pasrc ! audioconvert ! queue2 ! avenc_aac ! queue2 ! mux. \
  &gt; /dev/null 2&gt;&amp;1 &amp;
gstpid=$!

# Give stream a second to get going
sleep 1

# Ask kodi to start streaming using its JSON-RPC API
kodicmd &quot;$kodihost&quot; Player.Open \
        &quot;{\&quot;item\&quot;: { \&quot;file\&quot;: \&quot;udp://@$mcast:$mcastport\&quot; } }&quot; &gt; /dev/null

# wait for gst to end
wait &quot;$gstpid&quot;
&lt;/pre&gt;&lt;/blockquote&gt;

&lt;p&gt;I hope you find the approach useful.  I know I do.&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>Streaming the Linux desktop to Kodi using VLC and RTSP</title>
                <link>http://people.skolelinux.org/pere/blog/Streaming_the_Linux_desktop_to_Kodi_using_VLC_and_RTSP.html</link>
                <guid isPermaLink="true">http://people.skolelinux.org/pere/blog/Streaming_the_Linux_desktop_to_Kodi_using_VLC_and_RTSP.html</guid>
                <pubDate>Thu, 12 Jul 2018 02:00:00 +0200</pubDate>
                <description>&lt;p&gt;PS: See
&lt;ahref=&quot;http://people.skolelinux.org/pere/blog/Simple_streaming_the_Linux_desktop_to_Kodi_using_GStreamer_and_RTP.html&quot;&gt;the
followup post&lt;/a&gt; for a even better approach.&lt;/p&gt;

&lt;p&gt;A while back, I was asked by a friend how to stream the desktop to
my projector connected to Kodi.  I sadly had to admit that I had no
idea, as it was a task I never had tried.  Since then, I have been
looking for a way to do so, preferable without much extra software to
install on either side.  Today I found a way that seem to kind of
work.  Not great, but it is a start.&lt;/p&gt;

&lt;p&gt;I had a look at several approaches, for example
&lt;a href=&quot;https://github.com/mfoetsch/dlna_live_streaming&quot;&gt;using uPnP
DLNA as described in 2011&lt;/a&gt;, but it required a uPnP server, fuse and
local storage enough to store the stream locally.  This is not going
to work well for me, lacking enough free space, and it would
impossible for my friend to get working.&lt;/p&gt;

&lt;p&gt;Next, it occurred to me that perhaps I could use VLC to create a
video stream that Kodi could play.  Preferably using
broadcast/multicast, to avoid having to change any setup on the Kodi
side when starting such stream.  Unfortunately, the only recipe I
could find using multicast used the rtp protocol, and this protocol
seem to not be supported by Kodi.&lt;/p&gt;

&lt;p&gt;On the other hand, the rtsp protocol is working!  Unfortunately I
have to specify the IP address of the streaming machine in both the
sending command and the file on the Kodi server.  But it is showing my
desktop, and thus allow us to have a shared look on the big screen at
the programs I work on.&lt;/p&gt;

&lt;p&gt;I did not spend much time investigating codeces.  I combined the
rtp and rtsp recipes from
&lt;a href=&quot;https://wiki.videolan.org/Documentation:Streaming_HowTo/Command_Line_Examples/&quot;&gt;the
VLC Streaming HowTo/Command Line Examples&lt;/a&gt;, and was able to get
this working on the desktop/streaming end.&lt;/p&gt;

&lt;blockquote&gt;&lt;pre&gt;
vlc screen:// --sout \
  &#39;#transcode{vcodec=mp4v,acodec=mpga,vb=800,ab=128}:rtp{dst=projector.local,port=1234,sdp=rtsp://192.168.11.4:8080/test.sdp}&#39;
&lt;/pre&gt;&lt;/blockquote&gt;

&lt;p&gt;I ssh-ed into my Kodi box and created a file like this with the
same IP address:&lt;/p&gt;

&lt;blockquote&gt;&lt;pre&gt;
echo rtsp://192.168.11.4:8080/test.sdp \
  &gt; /storage/videos/screenstream.m3u
&lt;/pre&gt;&lt;/blockquote&gt;

&lt;p&gt;Note the 192.168.11.4 IP address is my desktops IP address.  As far
as I can tell the IP must be hardcoded for this to work.  In other
words, if someone elses machine is going to do the steaming, you have
to update screenstream.m3u on the Kodi machine and adjust the vlc
recipe.  To get started, locate the file in Kodi and select the m3u
file while the VLC stream is running.  The desktop then show up in my
big screen. :)&lt;/p&gt;

&lt;p&gt;When using the same technique to stream a video file with audio,
the audio quality is really bad.  No idea if the problem is package
loss or bad parameters for the transcode.  I do not know VLC nor Kodi
enough to tell.&lt;/p&gt;

&lt;p&gt;&lt;strong&gt;Update 2018-07-12&lt;/strong&gt;: Johannes Schauer send me a few
succestions and reminded me about an important step.  The &quot;screen:&quot;
input source is only available once the vlc-plugin-access-extra
package is installed on Debian.  Without it, you will see this error
message: &quot;VLC is unable to open the MRL &#39;screen://&#39;.  Check the log
for details.&quot;  He further found that it is possible to drop some parts
of the VLC command line to reduce the amount of hardcoded information.
It is also useful to consider using cvlc to avoid having the VLC
window in the desktop view.  In sum, this give us this command line on
the source end

&lt;blockquote&gt;&lt;pre&gt;
cvlc screen:// --sout \
  &#39;#transcode{vcodec=mp4v,acodec=mpga,vb=800,ab=128}:rtp{sdp=rtsp://:8080/}&#39;
&lt;/pre&gt;&lt;/blockquote&gt;

&lt;p&gt;and this on the Kodi end&lt;p&gt;

&lt;blockquote&gt;&lt;pre&gt;
echo rtsp://192.168.11.4:8080/ \
  &gt; /storage/videos/screenstream.m3u
&lt;/pre&gt;&lt;/blockquote&gt;

&lt;p&gt;Still bad image quality, though.  But I did discover that streaming
a DVD using dvdsimple:///dev/dvd as the source had excellent video and
audio quality, so I guess the issue is in the input or transcoding
parts, not the rtsp part.  I&#39;ve tried to change the vb and ab
parameters to use more bandwidth, but it did not make a
difference.&lt;/p&gt;

&lt;p&gt;I further received a suggestion from Einar Haraldseid to try using
gstreamer instead of VLC, and this proved to work great!  He also
provided me with the trick to get Kodi to use a multicast stream as
its source.  By using this monstrous oneliner, I can stream my desktop
with good video quality in reasonable framerate to the 239.255.0.1
multicast address on port 1234:

&lt;blockquote&gt;&lt;pre&gt;
gst-launch-1.0 ximagesrc use-damage=0 ! video/x-raw,framerate=30/1 ! \
  videoconvert ! queue2 ! \
  x264enc bitrate=8000 speed-preset=superfast tune=zerolatency qp-min=30 \
  key-int-max=15 bframes=2 ! video/x-h264,profile=high ! queue2 ! \
  mpegtsmux alignment=7 name=mux ! rndbuffersize max=1316 min=1316 ! \
  udpsink host=239.255.0.1 port=1234 ttl-mc=1 auto-multicast=1 sync=0 \
  pulsesrc device=$(pactl list | grep -A2 &#39;Source #&#39; | \
    grep &#39;Name: .*\.monitor$&#39; |  cut -d&quot; &quot; -f2|head -1) ! \
  audioconvert ! queue2 ! avenc_aac ! queue2 ! mux.
&lt;/pre&gt;&lt;/blockquote&gt;

&lt;p&gt;and this on the Kodi end&lt;p&gt;

&lt;blockquote&gt;&lt;pre&gt;
echo udp://@239.255.0.1:1234 \
  &gt; /storage/videos/screenstream.m3u
&lt;/pre&gt;&lt;/blockquote&gt;

&lt;p&gt;Note the trick to pick a valid pulseaudio source.  It might not
pick the one you need.  This approach will of course lead to trouble
if more than one source uses the same multicast port and address.
Note the ttl-mc=1 setting, which limit the multicast packages to the
local network.  If the value is increased, your screen will be
broadcasted further, one network &quot;hop&quot; for each increase (read up on
multicast to learn more. :)!&lt;/p&gt;

&lt;p&gt;Having cracked how to get Kodi to receive multicast streams, I
could use this VLC command to stream to the same multicast address.
The image quality is way better than the rtsp approach, but gstreamer
seem to be doing a better job.&lt;/p&gt;

&lt;blockquote&gt;&lt;pre&gt;
cvlc screen:// --sout &#39;#transcode{vcodec=mp4v,acodec=mpga,vb=800,ab=128}:rtp{mux=ts,dst=239.255.0.1,port=1234,sdp=sap}&#39;
&lt;/pre&gt;&lt;/blockquote&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>What is the most supported MIME type in Debian in 2018?</title>
                <link>http://people.skolelinux.org/pere/blog/What_is_the_most_supported_MIME_type_in_Debian_in_2018_.html</link>
                <guid isPermaLink="true">http://people.skolelinux.org/pere/blog/What_is_the_most_supported_MIME_type_in_Debian_in_2018_.html</guid>
                <pubDate>Mon, 9 Jul 2018 08:05:00 +0200</pubDate>
                <description>&lt;p&gt;Five years ago,
&lt;a href=&quot;http://people.skolelinux.org/pere/blog/What_is_the_most_supported_MIME_type_in_Debian_.html&quot;&gt;I
measured what the most supported MIME type in Debian was&lt;/a&gt;, by
analysing the desktop files in all packages in the archive.  Since
then, the DEP-11 AppStream system has been put into production, making
the task a lot easier.  This made me want to repeat the measurement,
to see how much things changed.  Here are the new numbers, for
unstable only this time:

&lt;p&gt;&lt;strong&gt;Debian Unstable:&lt;/strong&gt;&lt;/p&gt;

&lt;pre&gt;
  count MIME type
  ----- -----------------------
     56 image/jpeg
     55 image/png
     49 image/tiff
     48 image/gif
     39 image/bmp
     38 text/plain
     37 audio/mpeg
     34 application/ogg
     33 audio/x-flac
     32 audio/x-mp3
     30 audio/x-wav
     30 audio/x-vorbis+ogg
     29 image/x-portable-pixmap
     27 inode/directory
     27 image/x-portable-bitmap
     27 audio/x-mpeg
     26 application/x-ogg
     25 audio/x-mpegurl
     25 audio/ogg
     24 text/html
&lt;/pre&gt;

&lt;p&gt;The list was created like this using a sid chroot: &quot;cat
/var/lib/apt/lists/*sid*_dep11_Components-amd64.yml.gz| zcat | awk &#39;/^
- \S+\/\S+$/ {print $2 }&#39; | sort | uniq -c | sort -nr | head -20&quot;&lt;/p&gt;

&lt;p&gt;It is interesting to see how image formats have passed text/plain
as the most announced supported MIME type.  These days, thanks to the
AppStream system, if you run into a file format you do not know, and
want to figure out which packages support the format, you can find the
MIME type of the file using &quot;file --mime &amp;lt;filename&amp;gt;&quot;, and then
look up all packages announcing support for this format in their
AppStream metadata (XML or .desktop file) using &quot;appstreamcli
what-provides mimetype &amp;lt;mime-type&amp;gt;.  For example if you, like
me, want to know which packages support inode/directory, you can get a
list like this:&lt;/p&gt;

&lt;p&gt;&lt;blockquote&gt;&lt;pre&gt;
% appstreamcli what-provides mimetype inode/directory | grep Package: | sort
Package: anjuta
Package: audacious
Package: baobab
Package: cervisia
Package: chirp
Package: dolphin
Package: doublecmd-common
Package: easytag
Package: enlightenment
Package: ephoto
Package: filelight
Package: gwenview
Package: k4dirstat
Package: kaffeine
Package: kdesvn
Package: kid3
Package: kid3-qt
Package: nautilus
Package: nemo
Package: pcmanfm
Package: pcmanfm-qt
Package: qweborf
Package: ranger
Package: sirikali
Package: spacefm
Package: spacefm
Package: vifm
%
&lt;/pre&gt;&lt;/blockquote&gt;&lt;/p&gt;

&lt;p&gt;Using the same method, I can quickly discover that the Sketchup file
format is not yet supported by any package in Debian:&lt;/p&gt;

&lt;p&gt;&lt;blockquote&gt;&lt;pre&gt;
% appstreamcli what-provides mimetype  application/vnd.sketchup.skp
Could not find component providing &#39;mimetype::application/vnd.sketchup.skp&#39;.
%
&lt;/pre&gt;&lt;/blockquote&gt;&lt;/p&gt;

&lt;p&gt;Yesterday I used it to figure out which packages support the STL 3D
format:&lt;/p&gt;

&lt;p&gt;&lt;blockquote&gt;&lt;pre&gt;
% appstreamcli what-provides mimetype  application/sla|grep Package
Package: cura
Package: meshlab
Package: printrun
%
&lt;/pre&gt;&lt;/blockquote&gt;&lt;/p&gt;

&lt;p&gt;PS: A new version of Cura was uploaded to Debian yesterday.&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>