SSA stands for SubStation Alpha, and is named for a subtitle editor of the same name.
Files with .ssa file extension typically refer (in the world of digital video) to video subtitle files made with a tool called Sub Station Alpha or other tools compatible with its subtitle format.
.ssa files are rather common still, even tho they aren't technically as advanced as several competing subtitle formats, but the fact that .ssa files are compatible with several popular video manipulation tools, makes it popular, at least as a temporary format.
Even though .ssa is not very common as the final distributed format, you still occassionally find movies and videos bundled with .ssa subtitles. For playback, several players and subtitle filters do support the format -- most notably, an open source media player called Media Player Classic supports the format.
Convert Subtitles from SRT to SSA - Over the years there have been a number of different subtitle formats used for various applications. Something as simple as switching from one media player to another can cause big headaches when you find out that the subtitles you've come to rely on no longer work. In order to work around these problems it's important to be able to convert from one format to another.
Two of the most common subtitle formats are SRT created by SubRip, and SSA from SubStation Alpha. Since both of these are text-based formats, compared to the image based subtitles used for DVDs, it's actually quite easy to convert subtitles from one format to the other.
Convert Subtitles from SUB / IDX to SSA- VobSub's IDX and SUB subtitle format has beocme very popular do in large part to its flexibility and nearly universal compatibility with media players. But there are still times when you need something different, especially when dealing with older file formats like AVI where subtitles need to be in text format rather than images like VobSub rips from a DVD. Fortunately VobSub also includes a tool capable of converting subtitles to text-based formats like SRT or SSA.
Related glossary terms
Related software tools
Media Player Classic (Open source)
Media Player Classic is an extremely light-weight media player for Windows. It looks just like the good-old Media Player v6.4, but has lots of nice extra features.