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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: .

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 1920×1080 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


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 3840×2160 with 6hz via DisplayPort (mobile cpus support this only since Broadwell - but not Celeron/Pentium, here only 1920×1200 and 2560×1600 are allowed via DisplayPort)
  • maybe the TV/monitor can independently display the content when i.e. supplied via USB/nfs- or samba share.


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 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, 1920×1080 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 2560×1440 with 60Hz to the monitor


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 /
  • video: youtube, playing waterfalls or tree scenes? Is there better free content?
  • audio: a media player
  • weather: seeing videolike what the weather is: for example for Tokyo

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.
  • minidlna can offer video files to be played. Yet, still no live streaming of a computer screen. The DLNA protocol might specify also streaming types.


  • 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`
snippets/greenwindow.txt · Last modified: 2021/03/23 12:22 (external edit)