X-Git-Url: http://pere.pagekite.me/gitweb/homepage.git/blobdiff_plain/9779451a105ea2be678348ea7cfd4c5830059d6f..271aba3cc2efb48d8c0720a80a64f7845124cba6:/blog/archive/2018/07/07.rss?ds=inline diff --git a/blog/archive/2018/07/07.rss b/blog/archive/2018/07/07.rss index d46bf7d70f..a6a918ce74 100644 --- a/blog/archive/2018/07/07.rss +++ b/blog/archive/2018/07/07.rss @@ -6,6 +6,439 @@ http://people.skolelinux.org/pere/blog/ + + 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> + + + + + What is the most supported MIME type in Debian in 2018? + http://people.skolelinux.org/pere/blog/What_is_the_most_supported_MIME_type_in_Debian_in_2018_.html + http://people.skolelinux.org/pere/blog/What_is_the_most_supported_MIME_type_in_Debian_in_2018_.html + Mon, 9 Jul 2018 08:05:00 +0200 + <p>Five years ago, +<a href="http://people.skolelinux.org/pere/blog/What_is_the_most_supported_MIME_type_in_Debian_.html">I +measured what the most supported MIME type in Debian was</a>, 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: + +<p><strong>Debian Unstable:</strong></p> + +<pre> + 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 +</pre> + +<p>The list was created like this using a sid chroot: "cat +/var/lib/apt/lists/*sid*_dep11_Components-amd64.yml.gz| zcat | awk '/^ +- \S+\/\S+$/ {print $2 }' | sort | uniq -c | sort -nr | head -20"</p> + +<p>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 "file --mime &lt;filename&gt;", and then +look up all packages announcing support for this format in their +AppStream metadata (XML or .desktop file) using "appstreamcli +what-provides mimetype &lt;mime-type&gt;. For example if you, like +me, want to know which packages support inode/directory, you can get a +list like this:</p> + +<p><blockquote><pre> +% 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 +% +</pre></blockquote></p> + +<p>Using the same method, I can quickly discover that the Sketchup file +format is not yet supported by any package in Debian:</p> + +<p><blockquote><pre> +% appstreamcli what-provides mimetype application/vnd.sketchup.skp +Could not find component providing 'mimetype::application/vnd.sketchup.skp'. +% +</pre></blockquote></p> + +<p>Yesterday I used it to figure out which packages support the STL 3D +format:</p> + +<p><blockquote><pre> +% appstreamcli what-provides mimetype application/sla|grep Package +Package: cura +Package: meshlab +Package: printrun +% +</pre></blockquote></p> + +<p>PS: A new version of Cura was uploaded to Debian yesterday.</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> + + + Debian APT upgrade without enough free space on the disk... http://people.skolelinux.org/pere/blog/Debian_APT_upgrade_without_enough_free_space_on_the_disk___.html @@ -70,6 +503,14 @@ the packages that are simply too large to unpack. Today this was 'ghc', but I have run into other large packages causing similar problems earlier (like TeX).</p> +<p>Update 2018-07-08: Thanks to Paul Wise, I am aware of two +alternative ways to handle this. The "unattended-upgrades +--minimal-upgrade-steps" option will try to calculate upgrade sets for +each package to upgrade, and then upgrade them in order, smallest set +first. It might be a better option than my above mentioned script. +Also, "aptutude upgrade" can upgrade single packages, thus avoiding +the need for using "dpkg -i" in the script above.</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>