X-Git-Url: http://pere.pagekite.me/gitweb/homepage.git/blobdiff_plain/9779451a105ea2be678348ea7cfd4c5830059d6f..5ee2584c6469e6d4e3dd98b13ff5ef44fa65ad0b:/blog/archive/2018/07/index.html diff --git a/blog/archive/2018/07/index.html b/blog/archive/2018/07/index.html index 9522c2890b..1d0a1d7cc1 100644 --- a/blog/archive/2018/07/index.html +++ b/blog/archive/2018/07/index.html @@ -21,6 +21,487 @@

Entries from July 2018.

+
+
+ Sharing images with friends and family using RSS and EXIF/XMP metadata +
+
+ 31st July 2018 +
+
+

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 +<enclosure> RSS tag), but was unable to find a current supplier +of such frames. In the end I gave up that approach.

+ +

Some months ago, I discovered that +XScreensaver 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 +Kodi (both using +OpenELEC and +LibreELEC) provide the +Feedreader +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.

+ +

Armed with motivation and a test photo frame, I set out to generate +a RSS feed for the Kodi instance. I adjusted my Freedombox 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.

+ +

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:

+ +
+exiftool -headline='The RSS image title' \
+  -description='The RSS image description.' \
+  -subject+=for-family photo.jpeg
+
+ +

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.

+ +

Are there better ways to do this? Get in touch if you have better +suggestions.

+ +

As usual, if you use Bitcoin and want to show your support of my +activities, please send Bitcoin donations to my address +15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b.

+ +
+
+ + + Tags: debian, english. + + +
+
+
+ +
+
+ Simple streaming the Linux desktop to Kodi using GStreamer and RTP +
+
+ 12th July 2018 +
+
+

Last night, I wrote +a +recipe to stream a Linux desktop using VLC to a instance of Kodi. +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.

+ +

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 +the JSON-RPC API in +Kodi 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.

+ +
+#!/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"
+
+ +

I hope you find the approach useful. I know I do.

+ +

As usual, if you use Bitcoin and want to show your support of my +activities, please send Bitcoin donations to my address +15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b.

+ +
+
+ + + Tags: debian, english, kodi, video. + + +
+
+
+ +
+
+ Streaming the Linux desktop to Kodi using VLC and RTSP +
+
+ 12th July 2018 +
+
+

PS: See +the +followup post for a even better approach.

+ +

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.

+ +

I had a look at several approaches, for example +using uPnP +DLNA as described in 2011, 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.

+ +

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.

+ +

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.

+ +

I did not spend much time investigating codeces. I combined the +rtp and rtsp recipes from +the +VLC Streaming HowTo/Command Line Examples, and was able to get +this working on the desktop/streaming end.

+ +
+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}'
+
+ +

I ssh-ed into my Kodi box and created a file like this with the +same IP address:

+ +
+echo rtsp://192.168.11.4:8080/test.sdp \
+  > /storage/videos/screenstream.m3u
+
+ +

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. :)

+ +

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.

+ +

Update 2018-07-12: 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 + +

+cvlc screen:// --sout \
+  '#transcode{vcodec=mp4v,acodec=mpga,vb=800,ab=128}:rtp{sdp=rtsp://:8080/}'
+
+ +

and this on the Kodi end

+ +

+echo rtsp://192.168.11.4:8080/ \
+  > /storage/videos/screenstream.m3u
+
+ +

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.

+ +

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: + +

+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.
+
+ +

and this on the Kodi end

+ +

+echo udp://@239.255.0.1:1234 \
+  > /storage/videos/screenstream.m3u
+
+ +

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. :)!

+ +

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.

+ +
+cvlc screen:// --sout '#transcode{vcodec=mp4v,acodec=mpga,vb=800,ab=128}:rtp{mux=ts,dst=239.255.0.1,port=1234,sdp=sap}'
+
+ +

As usual, if you use Bitcoin and want to show your support of my +activities, please send Bitcoin donations to my address +15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b.

+ +
+
+ + + Tags: debian, english, kodi, video. + + +
+
+
+ +
+
+ What is the most supported MIME type in Debian in 2018? +
+
+ 9th July 2018 +
+
+

Five years ago, +I +measured what the most supported MIME type in Debian was, 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: + +

Debian Unstable:

+ +
+  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
+
+ +

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"

+ +

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 <filename>", and then +look up all packages announcing support for this format in their +AppStream metadata (XML or .desktop file) using "appstreamcli +what-provides mimetype <mime-type>. For example if you, like +me, want to know which packages support inode/directory, you can get a +list like this:

+ +

+% 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
+%
+

+ +

Using the same method, I can quickly discover that the Sketchup file +format is not yet supported by any package in Debian:

+ +

+% appstreamcli what-provides mimetype  application/vnd.sketchup.skp
+Could not find component providing 'mimetype::application/vnd.sketchup.skp'.
+%
+

+ +

Yesterday I used it to figure out which packages support the STL 3D +format:

+ +

+% appstreamcli what-provides mimetype  application/sla|grep Package
+Package: cura
+Package: meshlab
+Package: printrun
+%
+

+ +

PS: A new version of Cura was uploaded to Debian yesterday.

+ +

As usual, if you use Bitcoin and want to show your support of my +activities, please send Bitcoin donations to my address +15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b.

+ +
+
+ + + Tags: debian, english, isenkram. + + +
+
+
+
Debian APT upgrade without enough free space on the disk... @@ -88,6 +569,14 @@ 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).

+

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.

+

As usual, if you use Bitcoin and want to show your support of my activities, please send Bitcoin donations to my address 15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b.

@@ -111,6 +600,38 @@ activities, please send Bitcoin donations to my address

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