-<p>Her kan en se at tjenesten gir «404 Not Found» for curl i
-standardoppsettet, mens den gir «200 OK» hvis curl hevder å være Opera
-versjon 12.0. Offentlig elektronisk postjournal startet blokkeringen
-2017-03-02.</p>
-
-<p>Blokkeringen vil gjøre det litt vanskeligere å maskinelt hente
-informasjon fra oep.no. Kan blokkeringen være gjort for å hindre
-automatisert innsamling av informasjon fra OEP, slik Pressens
-Offentlighetsutvalg gjorde for å dokumentere hvordan departementene
-hindrer innsyn i
-<a href="http://presse.no/dette-mener-np/undergraver-offentlighetsloven/">rapporten
-«Slik hindrer departementer innsyn» som ble publiserte i januar
-2017</a>. Det virker usannsynlig, da det jo er trivielt å bytte
-User-Agent til noe nytt.</p>
-
-<p>Finnes det juridisk grunnlag for det offentlige å diskriminere
-webklienter slik det gjøres her? Der tilgang gis eller ikke alt etter
-hva klienten sier at den heter? Da OEP eies av DIFI og driftes av
-Basefarm, finnes det kanskje noen dokumenter sendt mellom disse to
-aktørene man kan be om innsyn i for å forstå hva som har skjedd. Men
-<a href="https://www.oep.no/search/result.html?period=dateRange&fromDate=01.01.2016&toDate=01.04.2017&dateType=documentDate&caseDescription=&descType=both&caseNumber=&documentNumber=&sender=basefarm&senderType=both&documentType=all&legalAuthority=&archiveCode=&list2=196&searchType=advanced&Search=Search+in+records">postjournalen
-til DIFI viser kun to dokumenter</a> det siste året mellom DIFI og
-Basefarm.
-<a href="https://www.mimesbronn.no/request/blokkering_av_tilgang_til_oep_fo">Mimes brønn neste</a>,
-tenker jeg.</p>
+<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>
projects / homepage.git / blobdiff