===== What? =====
Collecting pieces around something I call "green window project". 

Moving into a very small flat in Tokyo, with no good view outside? Ideas of using computer screens to replace windows are coming up. Most interesting is to collect content: waterfalls, nature and so on, free content. Kickstarter projects are also around: https://www.kickstarter.com/projects/atmoph/atmoph-window-your-room-can-be-anywhere .

===== TV or monitor? =====
Should a monitor or TV be used?
  * 24" and smaller, TV and monitor are equally expensive, but only TVs are available at bigger sizes
  * Are 1920x1080 pixel enough? Using 4k will bring in the issue of having to supply the resolution.
  * 4k nonitors are worse with contrast apparently
  * monitors also have USB-hub usually
  * C'T 11/2015 has optimized settings for TV: Samsung UE40HU6900S

===== TV settings =====
Many settings of a TV are not appropriate here. Example: Samsung UE40HU6900S
  * Βy default, the picture is cropped on all 4 edges. This can be fixed in the menu: picture/picture format/picture format: adapt
  * picture is optimized for TV by default, not monitor. To tune (german): 
    * Einstellungen / Bild / Hintergrundbel.: 6, Kontrast 90, Helligkeit 45, Schärfe 0
    * Bildformat: Bildanpassung
    * Erweiterte Einstellungen: Optimalkontrast: aus, Nur RGB-Modus: aus
    * Bildoptionen: Farbton: Warm2, Digital aufbereiten: aus, MPEG-Rauschfilter: aus, HDMI-Schwarzpegel: gering, Motion Plus: aus

===== resolution =====
The bigger the better, but..
  * higher resolutions are also harder to supply with compute devices
  * higher resolution content for the "greenwindow" is rarer
  * intel Haswell desktop cpus for desktops can supply UHD-resolution 3840x2160 with 6hz via DisplayPort (mobile cpus support this only since Broadwell - but not Celeron/Pentium, here only 1920x1200 and 2560x1600 are allowed via DisplayPort)
  * maybe the TV/monitor can independently display the content when i.e. supplied via USB/nfs- or samba share.

===== compute =====
Bringing audio, video or pictures to the TV/monitor
  * **TV/monitor** The device itself is able to show a picture show or the desired videos.
    * one can supply media on a usb stick or usb harddisk.
    * A DLNA server on a linuxbox can export directories with media files, the TV can then display it. Works also for 4k material - but a busy wlan does not provide the required bandwidth. **This is what I use mostly. Simple.** "dnf install -y minidlna; vi /etc/minidlna.conf; systemctl start minidlna"
  * **arm** raspberry pie 2 is reported to to 4k with 15fps [[https://www.raspberrypi.org/forums/viewtopic.php?f=38&t=79330|according to this]], additional hardware used? The kickstart project uses an intel core cpu.
  * **x86** I have an unused thinkpad around. It has displayport output, but no usable audio. Do USB graphiccards for 2560x and higher resolutions exist?
  * **HDMI1.4** can do 4k resolutions with 30hz, 1920x1080 with 60Hz
  * **HDMI2.0**
    * can do 4k resolutions with 60hz (some monitors with HDMI2.0 just entered the market)
    * only a few highend graphiccards support output to HDMI2.0
  * **Displayport1.1** does 4k resolutions with 30hz, the thinkpad x230 has an Intel(R) HD Graphics 4000 which only supports Displayport1.1a
  * **Displayport1.2** does 4k resolutions with 60hz, most 4k monitors are capable of this mode
  * **Displayport1.3** and Embedded Displayport 1.4a support 5k and 8k resolutions, but as of now no hardware supports it
  * **DVI** can only transport 2560x1440 with 60Hz to the monitor

===== content =====
The content should be free.
  * **pictures:**
    * A script, searching google image search for "nature" and displaying the results?
    * Script displaying random pictures from the harddisk, that have high resolution?
    * script displaying flicker pictures, i.e. from Hidehiko Sakashita / https://www.flickr.com/photos/hidesax/
  * **video:** youtube, playing waterfalls or tree scenes? Is there better free content?
    * fetching from youtube:
      * "dnf install ffmpeg youtube-dl"
      * lookup video from https://youtube.com , set filter for 4k. Example: [[https://www.youtube.com/watch?v=Czy0pXRRZcs|Jetman Dubai]] [[https://www.youtube.com/watch?v=lDi9uFcD7XI|pipedream]]
      * Use "youtube-dl -F <url>" to see available formats, then i.e. "youtube-dl -f 266+140 https://www.youtube.com/watch?v=s0MDY9fl-IA" to fetch both audio+video and have them merged with ffmpeg.
  * **audio:** a media player
  * weather: seeing videolike what the weather is
===== bringing content into the TV =====
Many computers like the thinkpad x230 here still have displayport 1.1a or other output which does not provide 4k resolution.
  * **Miracast** is the right protocol for mirroring a device to the TV. Yet, Linux as source is almost unusable. Was only reported to have worked on one wlan model. 
    * **miraclecast** seems active, https://github.com/albfan/miraclecast . But the wlan chip has to support certain functionality.
  * **minidlna** can offer video files to be played. Yet, still no live streaming of a computer screen. The [[https://en.wikipedia.org/wiki/Digital_Living_Network_Alliance|DLNA]] protocol might specify also streaming types.

===== notes =====
  * **xrandr:** I use xrandr directly to configure the screen connected to Linux: `xrandr --output HDMI1 --auto --below LVDS1`
  * **pulseaudio:** The snd_hda_codec_hdmi module provides here the audio output. After turning the TV off, the audio output often appears as "unplugged", even the TV is turned on again. Hacky workaround: `xrandr -s 0; xrandr --output HDMI1 --auto --below LVDS1`