X-Git-Url: http://pere.pagekite.me/gitweb/homepage.git/blobdiff_plain/a5f4bdf4e8b5407e0e69b78fc77db623de7d967c..6621ff349d531b5887d38da305c6d1fde095b36d:/blog/index.rss diff --git a/blog/index.rss b/blog/index.rss index 2faa9a8da3..cfcefdc156 100644 --- a/blog/index.rss +++ b/blog/index.rss @@ -6,6 +6,360 @@ http://people.skolelinux.org/pere/blog/ + + Time for an official MIME type for patches? + http://people.skolelinux.org/pere/blog/Time_for_an_official_MIME_type_for_patches_.html + http://people.skolelinux.org/pere/blog/Time_for_an_official_MIME_type_for_patches_.html + Thu, 1 Nov 2018 08:15:00 +0100 + <p>As part of my involvement in +<a href="https://gitlab.com/OsloMet-ABI/nikita-noark5-core">the Nikita +archive API project</a>, I've been importing a fairly large lump of +emails into a test instance of the archive to see how well this would +go. I picked a subset of <a href="https://notmuchmail.org/">my +notmuch email database</a>, all public emails sent to me via +@lists.debian.org, giving me a set of around 216 000 emails to import. +In the process, I had a look at the various attachments included in +these emails, to figure out what to do with attachments, and noticed +that one of the most common attachment formats do not have +<a href="https://www.iana.org/assignments/media-types/media-types.xhtml">an +official MIME type</a> registered with IANA/IETF. The output from +diff, ie the input for patch, is on the top 10 list of formats +included in these emails. At the moment people seem to use either +text/x-patch or text/x-diff, but neither is officially registered. It +would be better if one official MIME type were registered and used +everywhere.</p> + +<p>To try to get one official MIME type for these files, I've brought +up the topic on +<a href="https://www.ietf.org/mailman/listinfo/media-types">the +media-types mailing list</a>. If you are interested in discussion +which MIME type to use as the official for patch files, or involved in +making software using a MIME type for patches, perhaps you would like +to join the discussion?</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> + + + + + Measuring the speaker frequency response using the AUDMES free software GUI - nice free software + http://people.skolelinux.org/pere/blog/Measuring_the_speaker_frequency_response_using_the_AUDMES_free_software_GUI___nice_free_software.html + http://people.skolelinux.org/pere/blog/Measuring_the_speaker_frequency_response_using_the_AUDMES_free_software_GUI___nice_free_software.html + Mon, 22 Oct 2018 08:40:00 +0200 + <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> + + + + + Web browser integration of VLC with Bittorrent support + http://people.skolelinux.org/pere/blog/Web_browser_integration_of_VLC_with_Bittorrent_support.html + http://people.skolelinux.org/pere/blog/Web_browser_integration_of_VLC_with_Bittorrent_support.html + Sun, 21 Oct 2018 09:50:00 +0200 + <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> + + + + + Release 0.2 of free software archive system Nikita announced + http://people.skolelinux.org/pere/blog/Release_0_2_of_free_software_archive_system_Nikita_announced.html + http://people.skolelinux.org/pere/blog/Release_0_2_of_free_software_archive_system_Nikita_announced.html + Thu, 18 Oct 2018 14:40:00 +0200 + <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> + + + + + Fetching trusted timestamps using the rfc3161ng python module + http://people.skolelinux.org/pere/blog/Fetching_trusted_timestamps_using_the_rfc3161ng_python_module.html + http://people.skolelinux.org/pere/blog/Fetching_trusted_timestamps_using_the_rfc3161ng_python_module.html + Mon, 8 Oct 2018 12:30:00 +0200 + <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> + + + Automatic Google Drive sync using grive in Debian http://people.skolelinux.org/pere/blog/Automatic_Google_Drive_sync_using_grive_in_Debian.html @@ -311,419 +665,5 @@ them. I hope you too will do the same.</p> - - A bit more on privacy respecting health monitor / fitness tracker - http://people.skolelinux.org/pere/blog/A_bit_more_on_privacy_respecting_health_monitor___fitness_tracker.html - http://people.skolelinux.org/pere/blog/A_bit_more_on_privacy_respecting_health_monitor___fitness_tracker.html - Mon, 13 Aug 2018 09:00:00 +0200 - <p>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'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 -<a href="https://github.com/Freeyourgadget/Gadgetbridge/">Gadgetbridge</a>. -It provide cloudless collection and storing of data from a variety of -trackers. Its -<a href="https://github.com/Freeyourgadget/Gadgetbridge/#supported-devices">list -of supported devices</a> 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 -<a href="https://us.amazfit.com/shop/bip?variant=336750">Amazfit -Bip</a> and -<a href="http://www.xiaomimi6phone.com/xiaomi-mi-band-3-features-release-date-rumors/">Xiaomi -Band 3</a>.</p> - -<p>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 -<a href="https://www.gpsbabel.org/htmldoc-development/fmt_garmin_fit.html">Garmin -FIT files</a> containing the collected measurements. While -proprietary, FIT files apparently can be read at least by -<a href="https://www.gpsbabel.org">GPSBabel</a> and the -<a href="https://apps.nextcloud.com/apps/gpxpod">GpxPod</a> 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 -<a href="https://buy.garmin.com/en-US/US/p/564291">Garmin Forerunner -935</a>, 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.</p> - -<p>A final idea was to build ones own unit, perhaps by basing it on a -wearable hardware platforms like -<a href="https://learn.adafruit.com/flora-geo-watch">the Flora Geo -Watch</a>. 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.</p> - -<p>While I was working on tracking down links, I came across an -inspiring TED talk by Dave Debronkart about -<a href="https://archive.org/details/DavedeBronkart_2010X">being a -e-patient</a>, and discovered the web site -<a href="https://participatorymedicine.org/epatients/">Participatory -Medicine</a>. 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.</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> - - - - - Privacy respecting health monitor / fitness tracker? - http://people.skolelinux.org/pere/blog/Privacy_respecting_health_monitor___fitness_tracker_.html - http://people.skolelinux.org/pere/blog/Privacy_respecting_health_monitor___fitness_tracker_.html - Tue, 7 Aug 2018 16:00:00 +0200 - <p>Dear lazyweb,</p> - -<p>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 <strong>only</strong> 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 "the cloud"). The collected data should be available -using only free software. I'm not interested in depending on some -non-free software that will leave me high and dry some time in the -future. I'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 "cloud enabled"). -Is there an alternative? I'm not interested in giving money to people -requiring me to accept "privacy terms" to allow myself to measure my -own health.</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> - - - - - Sharing images with friends and family using RSS and EXIF/XMP metadata - http://people.skolelinux.org/pere/blog/Sharing_images_with_friends_and_family_using_RSS_and_EXIF_XMP_metadata.html - http://people.skolelinux.org/pere/blog/Sharing_images_with_friends_and_family_using_RSS_and_EXIF_XMP_metadata.html - Tue, 31 Jul 2018 23:30:00 +0200 - <p>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 -&lt;enclosure&gt; RSS tag), but was unable to find a current supplier -of such frames. In the end I gave up that approach.</p> - -<p>Some months ago, I discovered that -<a href="https://www.jwz.org/xscreensaver/">XScreensaver</a> 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 -<a href="https://kodi.tv">Kodi</a> (both using -<a href="https://www.openelec.tv/">OpenELEC</a> and -<a href="https://libreelec.tv">LibreELEC</a>) provide the -<a href="https://github.com/grinsted/script.screensaver.feedreader">Feedreader</a> -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.</p> - -<p>Armed with motivation and a test photo frame, I set out to generate -a RSS feed for the Kodi instance. I adjusted my <a -href="https://freedombox.org/">Freedombox</a> 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.</p> - -<p>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:</p> - -<blockquote><pre> -exiftool -headline='The RSS image title' \ - -description='The RSS image description.' \ - -subject+=for-family photo.jpeg -</pre></blockquote> - -<p>I initially tried the "-title" and "keyword" tags, but they were -invisible in digiKam, so I changed to "-headline" and "-subject". I -use the keyword/subject 'for-family' 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.</p> - -<p>Are there better ways to do this? Get in touch if you have better -suggestions.</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> - - - - - Simple streaming the Linux desktop to Kodi using GStreamer and RTP - http://people.skolelinux.org/pere/blog/Simple_streaming_the_Linux_desktop_to_Kodi_using_GStreamer_and_RTP.html - http://people.skolelinux.org/pere/blog/Simple_streaming_the_Linux_desktop_to_Kodi_using_GStreamer_and_RTP.html - Thu, 12 Jul 2018 17:55:00 +0200 - <p>Last night, I wrote -<a href="http://people.skolelinux.org/pere/blog/Streaming_the_Linux_desktop_to_Kodi_using_VLC_and_RTSP.html">a -recipe to stream a Linux desktop using VLC to a instance of Kodi</a>. -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.</p> - -<p>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 -<a href="https://kodi.wiki/view/JSON-RPC_API/v8">the JSON-RPC API in -Kodi</a> 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.</p> - -<blockquote><pre> -#!/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="$1" - cmd="$2" - params="$3" - curl --silent --header 'Content-Type: application/json' \ - --data-binary "{ \"id\": 1, \"jsonrpc\": \"2.0\", \"method\": \"$cmd\", \"params\": $params }" \ - "http://$host/jsonrpc" -} -cleanup() { - if [ -n "$kodihost" ] ; then - # Stop the playing when we end - playerid=$(kodicmd "$kodihost" Player.GetActivePlayers "{}" | - jq .result[].playerid) - kodicmd "$kodihost" Player.Stop "{ \"playerid\" : $playerid }" > /dev/null - fi - if [ "$gstpid" ] && kill -0 "$gstpid" >/dev/null 2>&1; then - kill "$gstpid" - fi -} -trap cleanup EXIT INT - -if [ -n "$1" ]; then - kodihost=$1 - shift -else - kodihost=kodi.local -fi - -mcast=239.255.0.1 -mcastport=1234 -mcastttl=1 - -pasrc=$(pactl list | grep -A2 'Source #' | grep 'Name: .*\.monitor$' | \ - cut -d" " -f2|head -1) -gst-launch-1.0 ximagesrc use-damage=0 ! video/x-raw,framerate=30/1 ! \ - videoconvert ! queue2 ! \ - x264enc bitrate=8000 speed-preset=superfast tune=zerolatency qp-min=30 \ - key-int-max=15 bframes=2 ! video/x-h264,profile=high ! queue2 ! \ - mpegtsmux alignment=7 name=mux ! rndbuffersize max=1316 min=1316 ! \ - udpsink host=$mcast port=$mcastport ttl-mc=$mcastttl auto-multicast=1 sync=0 \ - pulsesrc device=$pasrc ! audioconvert ! queue2 ! avenc_aac ! queue2 ! mux. \ - > /dev/null 2>&1 & -gstpid=$! - -# Give stream a second to get going -sleep 1 - -# Ask kodi to start streaming using its JSON-RPC API -kodicmd "$kodihost" Player.Open \ - "{\"item\": { \"file\": \"udp://@$mcast:$mcastport\" } }" > /dev/null - -# wait for gst to end -wait "$gstpid" -</pre></blockquote> - -<p>I hope you find the approach useful. I know I do.</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> - - - - - Streaming the Linux desktop to Kodi using VLC and RTSP - http://people.skolelinux.org/pere/blog/Streaming_the_Linux_desktop_to_Kodi_using_VLC_and_RTSP.html - http://people.skolelinux.org/pere/blog/Streaming_the_Linux_desktop_to_Kodi_using_VLC_and_RTSP.html - Thu, 12 Jul 2018 02:00:00 +0200 - <p>PS: See -<ahref="http://people.skolelinux.org/pere/blog/Simple_streaming_the_Linux_desktop_to_Kodi_using_GStreamer_and_RTP.html">the -followup post</a> for a even better approach.</p> - -<p>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.</p> - -<p>I had a look at several approaches, for example -<a href="https://github.com/mfoetsch/dlna_live_streaming">using uPnP -DLNA as described in 2011</a>, 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.</p> - -<p>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.</p> - -<p>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.</p> - -<p>I did not spend much time investigating codeces. I combined the -rtp and rtsp recipes from -<a href="https://wiki.videolan.org/Documentation:Streaming_HowTo/Command_Line_Examples/">the -VLC Streaming HowTo/Command Line Examples</a>, and was able to get -this working on the desktop/streaming end.</p> - -<blockquote><pre> -vlc screen:// --sout \ - '#transcode{vcodec=mp4v,acodec=mpga,vb=800,ab=128}:rtp{dst=projector.local,port=1234,sdp=rtsp://192.168.11.4:8080/test.sdp}' -</pre></blockquote> - -<p>I ssh-ed into my Kodi box and created a file like this with the -same IP address:</p> - -<blockquote><pre> -echo rtsp://192.168.11.4:8080/test.sdp \ - > /storage/videos/screenstream.m3u -</pre></blockquote> - -<p>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. :)</p> - -<p>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.</p> - -<p><strong>Update 2018-07-12</strong>: Johannes Schauer send me a few -succestions and reminded me about an important step. The "screen:" -input source is only available once the vlc-plugin-access-extra -package is installed on Debian. Without it, you will see this error -message: "VLC is unable to open the MRL 'screen://'. Check the log -for details." 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 - -<blockquote><pre> -cvlc screen:// --sout \ - '#transcode{vcodec=mp4v,acodec=mpga,vb=800,ab=128}:rtp{sdp=rtsp://:8080/}' -</pre></blockquote> - -<p>and this on the Kodi end<p> - -<blockquote><pre> -echo rtsp://192.168.11.4:8080/ \ - > /storage/videos/screenstream.m3u -</pre></blockquote> - -<p>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've tried to change the vb and ab -parameters to use more bandwidth, but it did not make a -difference.</p> - -<p>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: - -<blockquote><pre> -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=$(pactl list | grep -A2 'Source #' | \ - grep 'Name: .*\.monitor$' | cut -d" " -f2|head -1) ! \ - audioconvert ! queue2 ! avenc_aac ! queue2 ! mux. -</pre></blockquote> - -<p>and this on the Kodi end<p> - -<blockquote><pre> -echo udp://@239.255.0.1:1234 \ - > /storage/videos/screenstream.m3u -</pre></blockquote> - -<p>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 "hop" for each increase (read up on -multicast to learn more. :)!</p> - -<p>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.</p> - -<blockquote><pre> -cvlc screen:// --sout '#transcode{vcodec=mp4v,acodec=mpga,vb=800,ab=128}:rtp{mux=ts,dst=239.255.0.1,port=1234,sdp=sap}' -</pre></blockquote> - -<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> - - -