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 (4645B)

      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
     11 was no screen or projector available, or... No cable. The usual
     12 workaround that I've seen friends and colleagues use is to have everyone
     13 join jitsi/zoom/bbb/etc and do the screen sharing there. This works but
     14 feels like a grotesque variation of the "a multinational corporation's
     15 service as the easiest way of copying files between two nearby devices"
     16 entry from the crappy everyday tech bingo.
     17 
     18 So here is a response with television, a simple binary that takes
     19 screenshots of your desktop at regular intervals and serves the result
     20 over http on an amazingly well formatted html page that can be accessed
     21 by everyone over LAN/WLAN with their browser. It's *not* a video stream,
     22 it's really a 1fps style screensharing web thing which is plenty enough
     23 for slides, GUI/TUI/CLI action, etc.
     24 
     25 Of course I hear you say, "OK but then we have all these extra screens
     26 now!". Well true, but think about the new creative setups you can come
     27 up with, not everyone needs to have their own screen ffs! Take that as
     28 an opportunity to completely rearrange the room. Make small groups, I
     29 don't know. You can do it, I have faith in you.
     30 
     31 firefox, chrome, chromium, edge: works great (desktop and mobile)
     32 safari: does not work at all, *boooo* *throws stuff at safari*
     33 
     34 
     35 build
     36 -----
     37 
     38 go mod download
     39 go build -ldflags="-s -w" television.go
     40 
     41 
     42 installation
     43 ------------
     44 
     45 cp television /somewhere/nice
     46 cp -r www /also/somewhere/nice
     47 
     48 
     49 usage
     50 -----
     51 
     52 television [options]
     53 
     54 -idle   user activity detection (default off)
     55 
     56         Only works with X, makes use of X11 Screen Saver extension. By
     57         default, television will make a new screenshot every 2 seconds.
     58         This will work everywhere but is quite wasteful, when -idle is
     59         used screnshots are made only when user activity is detected. As
     60         a bonus, it means that the clients will reuse of the last cached
     61         image when there is no activity, therefore reducing drastically
     62         the network traffic too!
     63 
     64 -port   http port number (default 8888)
     65 
     66 -snap   custom snap command (default none)
     67 
     68         By default, television relies on kbinani/screenshot for taking a
     69         screenshot and pixiv/go-libjpeg for generating a jpg. This should
     70         work everywhere, however there can be more effective and efficient
     71         ways to take the screenshot (see examples), or it could be
     72         interesting to process the image before serving it. With -snap the
     73         whole mechanism for taking the screenshot, saving it as jpeg and
     74         placing it in the www folder is skipped and will be replace by
     75         your very own (TM) shell oneliner, assuming you have a working sh.
     76         Have fun. You deserve it.
     77 
     78 -www    www directory (default "./www")
     79 
     80         By default, television will look for the www folder in the same
     81         folder from which television is executed, this is far from ideal.
     82         I'm sure you have better ideas. I will suggest one in the
     83         examples section.
     84 
     85 
     86 client shortcut
     87 
     88 'f'     enter/exit fullscreen browser mode
     89 
     90 
     91 examples
     92 --------
     93 
     94 ./television
     95 
     96 What does this do?
     97 
     98 It just werks. Just run it like this from the git folder (after building
     99 it), and ask everyone to join http://your.local.ip.address:8888/tv
    100 
    101 ---
    102 
    103 ./television -port 666
    104 
    105 What does this do?
    106 
    107 -port 666           Somehow you insisted to serve the result on 
    108                     http://your.local.ip.address:666/tv
    109 
    110 ---
    111 
    112 television \
    113   -snap "scrot /tmp/www/tv/tv.tmp.jpg \
    114   && mv /tmp/www/tv/tv.tmp.jpg /tmp/www/tv/tv.jpg" \
    115   -www /tmp/www \
    116   -idle
    117 
    118 What does this do?
    119 
    120 -snap "scrot etc"   replaces the builtin screenshot and jpeg encoding by
    121                     scrot and this is to my knowledge the fastest and most
    122                     efficient way to take screenshots on X. See HACKING for
    123                     non-X feels.
    124                     
    125 -www /tmp/www       uses /tmp/www as root directory for serving the files.
    126                     on systems where /tmp is in fact tmpfs this is a good
    127                     idea because this could save a lot of disk write access.
    128 
    129 -idle               takes a screenshots only when user activity is detected,
    130                     namely keyboard input or mouse movement. Shh. Don't move.
    131                     See. Nothing happens.
    132 
    133 ---
    134 
    135 ./television \
    136     -snap "import \
    137     -colors 2 -dither FloydSteinberg -window root www/tv/tv.tmp.jpg \
    138     && mv www/tv/tv.tmp.jpg www/tv/tv.jpg"
    139 
    140 What does this do?
    141 
    142 -snap "import etc"  this is now a lowtechmag presentation :)
    143