Diffstub

Started from Alex Balk's (abalk200_comcast) diffstub project. Special thanks to Alex Giladi (Comcast) for contributing concepts and solutions to the project. Code contributions from Erik Ponder (eponde494_comcast) and Jovan Rosario (jriver829_comcast)

Info

This is a standalone NGINX C++ module for generateting an RF5261 (https://datatracker.ietf.org/doc/html/rfc5261) compliant MPED-DASH patch from 2 MPD files. This uses the PugiXML library to generate patch files. This software is in a development phase where features are being added and tested, and it may not be stable or feature-complete.

https://github.com/MPEGGroup/DASHSchema/blob/5th-Ed-AMD1/DASH-MPD.xsd

Requirements

• C++ 11
• NGINX 1.18.0 ~ (Only tested with Ubuntu 20.04)
• DASH.JS (Nightly Build) - (HTTP only) http://reference.dashif.org/dash.js/nightly/samples/dash-if-reference-player/index.html
• Shell Environment to execute scripts (LOCAL)

Shell Scripts

• ship_to_server.sh - Runs locally, Ships source code to external server
• run_on_server.sh - Run on server. Compiles module and starts nginx

Running Tests

• In VSCode

  • Run Build task (ctl/cmd + shift + B) -> "C/C++: Build Test File"
  • Run Tests with the "Run DIFFSTUB Tests" run configuration

• Command Line:

  • Compile tests with: g++ -std=c++11 -g test_ngx_diffstub_internal.cpp diffstub_xml_node.cpp ngx_diffstub_internal.cpp -o test_ngx_diffstub_internal

  • Run Tests: ./test_ngx_diffstub_internal

Setup

• ORIGIN:

  • Download and extract NGINX 1.18.0 source code to home directory ~

  cd ~
  wget http://nginx.org/download/nginx-1.18.0.tar.gz
  tar -zxvf nginx-1.18.0.tar.gz
  

• LOCAL:

  • Export the following ENV vars

  export $ORIGIN_HOST=<YOUR_ORIGIN_HOST_IP>
  export $ORIGIN_SSH_PORT=<ORIGIN_SSH_HOST_PORT>
  export $ORIGIN_USER=<ORIGIN_USER>  # e.g. ubuntu
  

  OR Edit ship_to_server.sh with your origin servers user, ip, and port.

  • Execute ship_to_server.sh:

  ./ship_to_server.sh
  

• ORIGIN:

  • Copy the nginx_diffstub.conf to /etc/nginx/nginx/conf, or add the required lines to existing conf. You can use nginx_diffstub.conf for reference

  sudo cp nginx_diffstub.conf /etc/nginx/nginx.conf
  

  • ***IF NGINX Source is installed in a different location than home (~), Edit run_on_server.sh.

  • Execute run_on_server.sh. This will compile the diffstub module and start nginx

  ./run_on_server
  

  • To Stop: sudo service nginx stop

• DASH.JS

  • Open Nightly Build: http://reference.dashif.org/dash.js/nightly/samples/dash-if-reference-player/index.html
  • Enter Origin IP and MPD location and 'load'

Current Limitations

- Only Supports HTTP streams (no DRM)
- Hardcoded TTL/Patch Headers
- Issue with Adding nested elements (i.e. adding a new element that contains grandchildren, currently WIP but incomplete)
- Issue with multiple directives (add/rem/rep) on a single element (Not Implemented)
- Does not provide legitimate error responses.

NOTE: Failing test cases have been disabled for now