<link>http://people.skolelinux.org/pere/blog/</link>
+ <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><p><img src="http://people.skolelinux.org/pere/blog/images/2018-10-22-audmes-measure-speakers.png" align="right" width="40%"/></p>
+
+<p>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'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
+<a href="https://www.diyaudioandvideo.com/Tutorial/SpeakerResponseTesting/">Speaker
+Testing and Analysis</a> describing how to test speakers, and it listing
+several software options, among them
+<a href="https://sourceforge.net/projects/audmes/">AUDio MEasurement
+System (AUDMES)</a>. 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
+<a href="http://novo.press/understanding-speaker-specifications-and-frequency-response/">Understanding
+Speaker Specifications and Frequency Response</a> and an article from
+ecoustics on
+<a href="https://www.ecoustics.com/articles/understanding-speaker-frequency-response/">Understanding
+Speaker Frequency Response</a>, 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.</p>
+
+<p>The first hurdle was that AUDMES hadn'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.</p>
+
+<p>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
+<a href="http://freehearingtestsoftware.com">Free Hearing Test
+Software</a>, 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.</p>
+
+<p>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
+<a href="https://bugs.debian.org/910876">include in Debian</a>? 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
+<a href="https://www.roomeqwizard.com/">REW</a>, but I want something
+that can be developed also when the vendor looses interest.</p>
+
+<p>As usual, if you use Bitcoin and want to show your support of my
+activities, please send Bitcoin donations to my address
+<b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p>
+</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><p>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
+<a href="https://www.nrk.no/">NRK</a>, Linux distributors like
+<a href="https://www.debian.org/">Debian</a> and
+<a href="https://www.ubuntu.com/">Ubuntu</a>, and of course the
+<a href="https://archive.org/">Internet archive</A>.
+
+<p>Almost a month ago
+<a href="https://tracker.debian.org/pkg/vlc-plugin-bittorrent">a new
+package adding Bittorrent support to VLC</a> became available in
+Debian testing and unstable. To test it, simply install it like
+this:</p>
+
+<p><pre>
+apt install vlc-plugin-bittorrent
+</pre></p>
+
+<p>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
+<a href="https://archive.org/details/CopyingIsNotTheft1080p">Internet
+Archive page with movies</a> using a web browser and click on the
+torrent link to start streaming the movie.</p>
+
+<p>Note, there is still some misfeatures in the plugin. One is the
+fact that it will hang and
+<a href="https://github.com/johang/vlc-bittorrent/issues/13">block VLC
+from exiting until the torrent streaming starts</a>. Another is the
+fact that it
+<a href="https://github.com/johang/vlc-bittorrent/issues/9">will pick
+and play a random file in a multi file torrent</a>. 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.</p>
+
+<p>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.</p>
+
+<p>As usual, if you use Bitcoin and want to show your support of my
+activities, please send Bitcoin donations to my address
+<b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p>
+</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><p>This morning, the new release of the
+<a href="https://gitlab.com/OsloMet-ABI/nikita-noark5-core/">Nikita
+Noark 5 core project</a> was
+<a href="https://lists.nuug.no/pipermail/nikita-noark/2018-October/000406.html">announced
+on the project mailing list</a>. 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):
+
+<ul>
+ <li>Fix typos in REL names</li>
+ <li>Tidy up error message reporting</li>
+ <li>Fix issue where we used Integer.valueOf(), not Integer.getInteger()</li>
+ <li>Change some String handling to StringBuffer</li>
+ <li>Fix error reporting</li>
+ <li>Code tidy-up</li>
+ <li>Fix issue using static non-synchronized SimpleDateFormat to avoid
+ race conditions</li>
+ <li>Fix problem where deserialisers were treating integers as strings</li>
+ <li>Update methods to make them null-safe</li>
+ <li>Fix many issues reported by coverity</li>
+ <li>Improve equals(), compareTo() and hash() in domain model</li>
+ <li>Improvements to the domain model for metadata classes</li>
+ <li>Fix CORS issues when downloading document</li>
+ <li>Implementation of case-handling with registryEntry and document upload</li>
+ <li>Better support in Javascript for OPTIONS</li>
+ <li>Adding concept description of mail integration</li>
+ <li>Improve setting of default values for GET on ny-journalpost</li>
+ <li>Better handling of required values during deserialisation </li>
+ <li>Changed tilknyttetDato (M620) from date to dateTime</li>
+ <li>Corrected some opprettetDato (M600) (de)serialisation errors.</li>
+ <li>Improve parse error reporting.</li>
+ <li>Started on OData search and filtering.</li>
+ <li>Added Contributor Covenant Code of Conduct to project.</li>
+ <li>Moved repository and project from Github to Gitlab.</li>
+ <li>Restructured repository, moved code into src/ and web/.</li>
+ <li>Updated code to use Spring Boot version 2.</li>
+ <li>Added support for OAuth2 authentication.</li>
+ <li>Fixed several bugs discovered by Coverity.</li>
+ <li>Corrected handling of date/datetime fields.</li>
+ <li>Improved error reporting when rejecting during deserializatoin.</li>
+ <li>Adjusted default values provided for ny-arkivdel, ny-mappe,
+ ny-saksmappe, ny-journalpost and ny-dokumentbeskrivelse.</li>
+ <li>Several fixes for korrespondansepart*.</li>
+ <li>Updated web GUI:
+ <ul>
+ <li>Now handle both file upload and download.</li>
+ <li>Uses new OAuth2 authentication for login.</li>
+ <li>Forms now fetches default values from API using GET.</li>
+ <li>Added RFC 822 (email), TIFF and JPEG to list of possible file formats.</li>
+ </ul></li>
+</ul>
+
+<p>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(-).</p>
+
+<p>If free and open standardized archiving API sound interesting to
+you, please contact us on IRC
+(<a href="irc://irc.freenode.net/%23nikita">#nikita on
+irc.freenode.net</a>) or email
+(<a href="https://lists.nuug.no/mailman/listinfo/nikita-noark">nikita-noark
+mailing list</a>).</p>
+
+<p>As usual, if you use Bitcoin and want to show your support of my
+activities, please send Bitcoin donations to my address
+<b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p>
+</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><p>I have earlier covered the basics of trusted timestamping using the
+'openssl ts' client. See blog post for
+<a href="http://people.skolelinux.org/pere/blog/Public_Trusted_Timestamping_services_for_everyone.html">2014</a>,
+<a href="http://people.skolelinux.org/pere/blog/syslog_trusted_timestamp___chain_of_trusted_timestamps_for_your_syslog.html">2016</a>
+and
+<a href="http://people.skolelinux.org/pere/blog/Idea_for_storing_trusted_timestamps_in_a_Noark_5_archive.html">2017</a>
+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
+<a href="https://dev.entrouvert.org/projects/python-rfc3161">the
+rfc3161 library</a> 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
+<a href="https://github.com/trbs/rfc3161ng/">the rfc3161ng library</a>,
+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
+<a href="https://tracker.debian.org/pkg/python-rfc3161ng">available in
+Debian</a>, and a few days ago it entered Debian unstable and testing.</p>
+
+<p>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:</p>
+
+<pre>
+#!/usr/bin/python3
+
+"""
+
+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.
+
+"""
+
+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('https://freetsa.org/files/tsa.crt', cert_f)
+ ca_data_data = fetch('https://freetsa.org/files/cacert.pem', ca_f)
+
+ # Then timestamp the message
+ timestamper = \
+ rfc3161ng.RemoteTimestamper('http://freetsa.org/tsr',
+ certificate=certificate_data)
+ data = b"Python forever!\n"
+ tsr = timestamper(data=data, return_tsr=True)
+
+ # Finally, convert message and response to something 'openssl ts' can verify
+ store(msg_f, data)
+ store(tsr_f, pyasn1.codec.der.encoder.encode(tsr))
+ args = ["openssl", "ts", "-verify",
+ "-data", msg_f.name,
+ "-in", tsr_f.name,
+ "-CAfile", ca_f.name,
+ "-untrusted", cert_f.name]
+ subprocess.check_call(args)
+
+if '__main__' == __name__:
+ main()
+</pre>
+
+<p>The code fetches the required certificates, store them as temporary
+files, timestamp a simple message, store the message and timestamp to
+disk and ask 'openssl ts' to verify the timestamp. A timestamp is
+around 1.5 kiB in size, and should be fairly easy to store for future
+use.</p>
+
+<p>As usual, if you use Bitcoin and want to show your support of my
+activities, please send Bitcoin donations to my address
+<b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p>
+</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>
projects / homepage.git / blobdiff