Captioning Tutorials

Overview of Tutorials

These tutorials focus solely on captioning audio or video for the web. They do not cover "burn-in" sub-titling or other forms of captioning or creation of audio descriptions. The tutorials use MAGpie 2.02, the free Java-based caption sychronization application developed by NCAM. (Note: some hints on installing MAGpie are below.). We target output to QuickTime, Windows Media Player, and Flash.

You can download the tutorial files (19 MB) used on these pages. You will need to unzip them. The video source used in these tutorials was excerpted and modified from the Disability Program Navigator Second Annual Training.

Captioning in a Nut Shell

For captioning you will need a video (or audio) clip and a transcript. Your video will need to be appropriately sized and encoded. We recommend an aspect ratio of 320 by 240 pixels for web video. This is standard for web video. If you are unsure what movie format (WMV, FLV, AVI, MOV, etc.) the player you want to target can handle, Wikipedia is a good source to find encodings for QuickTime, encodings for Windows Media Player, encodings for Real Player and encodings for other software media players. The CCforFlash player we use in these tutorials takes video encoded as FLV. We will use an AVI file for our Windows Media Player example and a MOV file for our QuickTime example.

Though MAGpie can use a RealPlayer file for sychronization, this is a Windows-only option for MAGpie and requires a special plugin. Thus we recommend starting with your video in MOV, MPEG, or AVI format, or, if you only have audio, MP3 or WAV format. MAGpie uses QuickTime for playback during the synchronization process and QuickTime can play any of these formats.

If you need to convert your video into one of these formats, try Super © (on Windows) or ffmpegX (on the Mac). Both are tools with a graphical user interface. They have their quirks and don't always produce the best compression, but they won't cost you a penny. Linux users are probably already familiar with FFMPEG, a command-line program that relies on open source libraries to perform conversion (and which is the namesake of ffmpegX). One of the best ways to get video to FLV is Adobe's Flash Encoder. This program is free for Windows users. With it, you can capture the video input from a camera attached to a USB or video capture card on your computer and render it straight into a FLV file. Though Super© can convert to FLV, you will get better compression and much better final results using the video conversion tools in Flash Professional 8 or later. Flash can convert from many different types of movie formats, including AVI, MPEG, MOV, and WMV.

Our preparing the transcript tutorial has some recommendations for obtaining transcripts.

Once you have your video and transcript, captioning for the web breaks down into three steps.

  1. "Chunk" the transcript into caption-length segments.
  2. Synchronize the video or audio with the caption-track by assigning each caption chunk a time-code corresponding to the moment in the video or audio track where the caption chunk is spoken.
  3. "Glue" together the time-coded caption track and the video or audio track using a media player-specific integration file (SMIL, SAMI with ASX, DFXP, etc.).

The captioned audio or video is then ready to upload to the web. Our tutorials cover each of these steps. The tutorials are meant to be read and worked-through in order. These tutorials are meant to get you up and running quickly. For further information on captioning and detailed tutorials, see the excellent WebAIM captioning articles.

Outline of Tutorials

Preparing the Transcript
Covers chunking of the transcript into caption-length segments. We give advice on getting and preparing the transcript. We then demonstrate using a couple of programs to assist in chunking and spacing the transcript file for import into MAGpie. We also discuss chunking conventions.
Synchronizing Captions Using MAGpie
Covers use of MAGpie to create and export a caption track synchronized with a video or audio track. In addition to step-by-step instructions, this tutorial includes a captioned Flash movie that gives an overview of the process.
Publishing to the Web
With QuickTime
Covers tweaking the MAGpie-generated QuickTime caption text and SMIL files and linking to a captioned QuickTime movie embedded in a web page. We include JavaScript code that allows for the movie to be controlled via the keyboard.
With Windows Media Player
Covers tweaking the MAGpie-generated SAMI file, authoring the ASX file, and linking directly to WMP movies.
With Flash
Covers using the caption-capable movie player, CC for Flash Player, developed by the National Center for Accessible Media (NCAM) , to embed a caption track for movie playback in Flash and covers embedding the Flash movie player in a web page.

Hints on Installing MAGpie in Windows

NCAM's MAGpie version 2 is a freely available Java-based application that helps synchronize an audio track in a video or audio clip with a transcript. Installing MAGpie in Mac OS X is a painless experience. Simply download and run the appropriate installer. In Windows, however, installation of MAGpie must follow a particular order or the software can fail to function—or even launch.

You will need the following:

The most important thing to remember is that you must install all components in the given order and, prior to installation, you must uninstall all versions of the components and delete any left over program-related directories. Also, it is very likely MAGpie will quit working if you upgrade your JRE after installing MAGpie. If MAGpie quits working, uninstall and reinstall all components.

Perform the following steps, in order.

  1. Uninstall Java and QuickTime. Start → Control Panel → Add or Remove Programs
  2. Remove any directories associated with these programs and kill any processes related to them. You will likely find left over Java directories in C:\Program Files\Java. To kill any lingering Java or QuickTime processes, use the Task Manager (available by right-clicking in the Taskbar).
  3. If applicable, uninstall any previous versions of MAGpie or GRiNs
  4. Install the JRE
  5. Install QuickTime
  6. Install GRiNs (if you want to caption Real Media Player files)
  7. Install MAGpie

For more information and detailed installation instructions, see the MAGpie documentation.