Tech insights

  A Proof-of-Concept Browser written in Javascript for minimal Web 2.0 browsing experience. This DOES NOT depend on any browser engine like Blink, Gecko or Webkit. Use an existing HTML rendering engine like netsurf or roll-out your own . This uses QuickJS-ng for JS runtime, Linkedom for DOM API and curl for network downloads. Font decoration uses Terminal ANSI escape codes . Since linkedom is an npm module, it needs to be converted to ES6 module for use with quickjs.  npm install linkedom npx esbuild node_modules/linkedom/esm/index.js \     --bundle \     --format=esm \     --outfile= linkedom.bundle.js \     --platform=neutral         Code https://gitlab.com/atamariya/quickjs/-/blob/dev/ldom.js https://gitlab.com/atamariya/quickjs/-/blob/dev/net.js https://gitlab.com/atamariya/quickjs/-/blob/dev/render.js   Lessons Learnt std.urlGet() only supports stateless downloads. For form posts, header manipulati...

Internet Printing Protocol Printing with  Internet Printing Protocol (IPP)  involves sending a Unirast   Format (URF) image with appropriate protocol headers to port 631. It is the basis for standards like  Windows Mopria Alliance , Apple   AirPrint , and IPP Everywhere .  It is also called  Driverless Printing   since this doesn't involve installing any printer specific driver. On Plan 9, printing involves three steps: Convert the document to PDF using lp Convert the PDF to URF using  gs  (use urfgray, urfrgb or urfcmyk device) Send the request to the printer using hget IPP header ( req.bin in the below script) contains page output options like paper size, margins etc. This is generated   using ippenc.c .        #!/bin/rc HOST=$1 FILE=$2 TFILE=/tmp/a.pdf URL=( http://$HOST:631/ipp/print/ ) if (! ~ $#* 2)    echo 'Usage: $0 <printer-ip> <file>'     lp -d stdout $FILE > $TFILE...

Video pipeline in action Two important points about videos: A video is a series of images. RGB format is used for display. YUV format is used for storage and transmission.  Recording   ──────────────────────────────────────────────────────── [Video Source] → [Frame Processing] → [Video Encode] ┐                                                                                                      ├→ [Mux] → [Container Stream] [Audio Source] → [Audio Processing] → [Audio Encode] ┘ Playback   ──────────────────────────────────────────────────────── [Container Stream] → [Demux] → [Video Decode] → [Video Sink]                                   ...

Stream a single window or the whole screen via Real Time Streaming Protocol (RTSP). This uses MJPEG stream over TCP-interleave . Plan 9 /dev/screen and /dev/window produces RGBA byte stream with Plan 9 headers. This is converted to JPEG using tojpg and streamed using RTSP. In the video, host port 12554 port is being forwarded to 554 in the Plan 9 VM.  ffplay -rtsp_transport tcp rtsp://localhost:12554/ stream1       Code https://gitlab.com/atamariya/plan9front/-/blob/dev/sys/src/cmd/rtsp/server.c https://gitlab.com/atamariya/plan9front/-/blob/dev/sys/src/cmd/jpg/tojpg.c https://gitlab.com/atamariya/plan9front/-/blob/dev/sys/src/cmd/jpg/writejpg.c ( Update 16/03/2026 : server.c is moved to /sys/src/cmd/stream/rtsp/)   Youtube Live Use Real-Time Messaging Protocol ( RTMP ) to feed into Youtube / Twitch Live. video/hj264 -f 25 /dev/screen | video/rtmp -a /dev/audio rtmp://.... rtmp://...         Note:   The encoder and the publisher pr...

  Demo of Wifi router connection using WiFi Protected Setup (WPS). WiFi Protected Setup (WPS) allows you to connect to an Access Point (router) via Push Button Control (PBC) or a temporary PIN.   Authentication Flow   Direction Message / Contents Phase / Purpose Supplicant → AP Authentication Request 802.11 Authentication Supplicant ← AP Authentication Response Supplicant → AP Association Request 802.11 Association Supplicant ← AP Association Response Supplicant → AP EAPOL-Start EAP Initiation Supplicant ← AP EAP-Request Identity Supplicant → AP EAP-Response Identity (Identity: “WFA-SimpleConfig-Registrar-1-0”) Supplicant ← AP WSC Start Enrollee → Registrar (M1) N1 || Descripti...

  Share media content with UPnP / DLNA capable players. This is a proof-of-concept of network programming  (TCP and UDP)  in Plan 9. For information, man udp is a useful place to get started.   Device Quirks VLC VLC looks for "urn:schemas-upnp-org:service:ContentDirectory:1" instead of "urn:schemas-upnp-org:device:MediaServer:1" during M-SEARCH.   LG WebOS TV   LG WebOS TV needs the services "urn:schemas-upnp-org:service:ConnectionManager:1" and "urn:microsoft.com:service:X_MS_MediaReceiverRegistrar:1" in addition to "urn:schemas-upnp-org:service:ContentDirectory:1" in device.xml.   It also seems to remember the UUIDs for a particular IP address. If you change the UUID of our application and it doesn't appear in the TV, restarting the TV might help.  Code https://gitlab.com/atamariya/plan9front/-/blob/dev/sys/src/cmd/upnp/server.c