X-Git-Url: http://pere.pagekite.me/gitweb/homepage.git/blobdiff_plain/01e08cd74c52f3d629bbc6958e005e430b0921a0..5ee2584c6469e6d4e3dd98b13ff5ef44fa65ad0b:/blog/archive/2018/07/index.html diff --git a/blog/archive/2018/07/index.html b/blog/archive/2018/07/index.html index f7ece8c181..1d0a1d7cc1 100644 --- a/blog/archive/2018/07/index.html +++ b/blog/archive/2018/07/index.html @@ -21,6 +21,200 @@

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 @@ -29,7 +223,11 @@ 12th July 2018
-

A while back, I was asked by a friend how to stream the desktop to +

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 @@ -78,7 +276,7 @@ echo rtsp://192.168.11.4:8080/test.sdp \

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 +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. :)

@@ -88,6 +286,79 @@ 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.

@@ -96,7 +367,7 @@ activities, please send Bitcoin donations to my address
- Tags: debian, english, video. + Tags: debian, english, kodi, video.
@@ -329,6 +600,38 @@ activities, please send Bitcoin donations to my address

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