television

a simple LAN/WLAN desktop public broadcasting service
git clone http://git.permacomputing.net/repos/television.git # read-only access
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README (4624B)

      1 television
      2 ==========
      3 
      4 A simple LAN/WLAN screen public http broadcasting service.
      5 
      6 
      7 motivation
      8 ----------
      9 
     10 I've been in situations of giving a lecture or a workshop where there was no
     11 screen or projector available, or... No cable. The usual workaround that I've
     12 seen friends and colleagues use is to have everyone join jitsi/zoom/bbb/etc and
     13 do the screen sharing there. This works but feels like a grotesque variation of
     14 the "a multinational corporation's service as the easiest way of copying files
     15 between two nearby devices" entry from the crappy everyday tech bingo.
     16 
     17 So here is a response with television, a simple binary that takes screenshots
     18 of your desktop at regular intervals and serves the result over http on an
     19 amazingly well formatted html page that can be accessed by everyone over
     20 LAN/WLAN with their browser. It's *not* a video stream, it's really a 1fps
     21 style screensharing web thing which is plenty enough for slides, GUI/TUI/CLI
     22 action, etc.
     23 
     24 Of course I hear you say, "OK but then we have all these extra screens now!".
     25 Well true, but think about the new creative setups you can come up with, not
     26 everyone needs to have their own screen ffs! Take that as an opportunity to
     27 completely rearrange the room. Make small groups, I don't know. You can do it,
     28 I have faith in you.
     29 
     30 firefox, chrome, chromium, edge: works great (desktop and mobile)
     31 safari: does not work at all, *boooo* *throws stuff at safari*
     32 
     33 
     34 build
     35 -----
     36 
     37 go mod download
     38 go build -ldflags="-s -w" television.go
     39 
     40 
     41 installation
     42 ------------
     43 
     44 cp television /somewhere/nice
     45 cp -r www /also/somewhere/nice
     46 
     47 
     48 usage
     49 -----
     50 
     51 television [options]
     52 
     53 -idle   user activity detection (default off)
     54 
     55         Only works with X, makes use of X11 Screen Saver extension.
     56         By default, television will make a new screenshot every 2 seconds.
     57         This will work everywhere but is quite wasteful, when -idle is used
     58         screnshots are made only when user activity is detected. As a bonus,
     59         it means that the clients will reuse of the last cached image when
     60         there is no activity, therefore reducing drastically the network
     61         traffic too!
     62 
     63 -port   http port number (default 8888)
     64 
     65 -snap   custom snap command (default none)
     66 
     67         By default, television relies on kbinani/screenshot for taking a
     68         screenshot and pixiv/go-libjpeg for generating a jpg. This should
     69         work everywhere, however there can be more effective and efficient
     70         ways to take the screenshot (see examples), or it could be interesting
     71         to process the image before serving it. With -snap the whole mechanism
     72         for taking the screenshot, saving it as jpeg and placing it in the
     73         www folder is skipped and will be replace by your very own (TM)
     74         shell oneliner, assuming you have a working sh. Have fun. You deserve
     75         it.
     76 
     77 -www    www directory (default "./www")
     78 
     79         By default, television will look for the www folder in the same
     80         folder from which television is executed, this is far from ideal.
     81         I'm sure you have better ideas. I will suggest one in the examples
     82         section.
     83 
     84 
     85 client shortcut
     86 
     87 'f'     enter/exit fullscreen browser mode
     88 
     89 
     90 examples
     91 --------
     92 
     93 ./television
     94 
     95 What does this do?
     96 
     97 It just werks. Just run it like this from the git folder (after building it),
     98 and ask everyone to join http://your.local.ip.address:8888/tv
     99 
    100 ---
    101 
    102 ./television -port 666
    103 
    104 What does this do?
    105 
    106 -port 666           Somehow you insisted to serve the result on 
    107                     http://your.local.ip.address:666/tv
    108 
    109 ---
    110 
    111 television \
    112   -snap "scrot /tmp/www/tv/tv.tmp.jpg \
    113   && mv /tmp/www/tv/tv.tmp.jpg /tmp/www/tv/tv.jpg" \
    114   -www /tmp/www \
    115   -idle
    116 
    117 What does this do?
    118 
    119 -snap "scrot etc"   replaces the builtin screenshot and jpeg encoding by scrot
    120                     and this is to my knowledge the fastest and most efficient
    121                     way to take screenshots on X. See HACKING for non-X feels.
    122                     
    123 -www /tmp/www       uses /tmp/www as root directory for serving the files.
    124                     on systems where /tmp is in fact tmpfs this is a good idea
    125                     because this could save a lot of disk write access.
    126 
    127 -idle               takes a screenshots only when user activity is detected,
    128                     namely keyboard input or mouse movement. Shh. Don't move.
    129                     See. Nothing happens.
    130 
    131 ---
    132 
    133 ./television \
    134     -snap "import \
    135     -colors 2 -dither FloydSteinberg -window root www/tv/tv.tmp.jpg \
    136     && mv www/tv/tv.tmp.jpg www/tv/tv.jpg"
    137 
    138 What does this do?
    139 
    140 -snap "import etc"  this is now a lowtechmag presentation <3