<link>http://people.skolelinux.org/pere/blog/</link>
+ <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><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>
+</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><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>
+</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><p>A while back, I was asked by a friend how to stream the desktop to
+ <description><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
<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.m4u on the Kodi machine and adjust the vlc
-repice. To get started, locate the file in Kodi and select the m3u
+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>
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>
projects / homepage.git / blobdiff