Tech Notes at Oblongata Dot Org

This is a collection of notes on technical matters. You can also find slides I have created for presentations on technical matters in the Presentations subdirectory.

mencoder

The mencoder utility is part of the MPlayer application. MPlayer is a media player popular with users of open source software with a stunning lot of features and support for a very wide array of video and audio codecs, while mencoder is an MPlayer component that provides video and audio encoding and transcoding capabilities.

The Tesla concert video was captured as an MOV format file with a consumer-grade digital camera. When transcoding it to an AVI format file, mencoder helpfully deleted a duplicate frame from the video. Unfortunately, that put the video and sound out of sync with each other. The -audio-delay option was set to a value of -0.3 to fix that problem.
```
$ mencoder telsa_popcorn.mov -oac mp3lame -ovc lavc \
          -audio-delay -0.3 -o tesla_popcorn.avi
```

SSI

SSI stands for "Server Side Includes". It's a means of embedding directives in Webpage markup for the server to execute before sending out the page in response to an HTTP request (presumably from a Web browser). SSI's syntax is very simple, and it isn't terribly powerful -- it is by no means a "programming language" in any meaningful sense of the term. It just serves much the same purpose as the simplest uses for something like PHP.

Parts of the pages on this site -- parts that are the same on every page of the main site, to be specific -- exist in only one file each. The contents of that file are included in the files full of markup that are sent to your browser by SSI. The syntax for this is extremely simple. For instance, the markup for the menu is stored in a file called menu.txt in the root directory of this website, and included in each Web page using an #include directive.
```

```
If you're running Apache, and support for SSI is "turned on", you can make sure it works in your current directory by adding some lines to the .htaccess file in the current directory. Then, any files with a .shtml filename extension will be parsed and SSI code in the file will be executed before the page is sent to the browser. To make sure it works in all directories, put those lines in the .htaccess file for your site's root directory, and any subdirectories should pick up the configuration.
```
AddType text/html .shtml
AddHandler server-parsed .shtml
Options Indexes FollowSymLinks Includes
```