Aegisub

{{Short description|Open-source computer program for subtitle editing}}

{{More citations needed|date=November 2021}}

{{Infobox software

| name = Aegisub

| logo = Aegisub-logo.svg

| screenshot = Aegisub screenshot.png

| caption = Aegisub demonstrating visual typesetting and karaoke features

| developer = Niels Martin Hansen, Rodrigo Braz Monteiro, Thomas Goyne, and others

| latest release version = 3.4.2{{cite web |title=Aegisub 3.4.0 Released |url=https://aegisub.org/blog/aegisub-3.4.0-released/ |date=18 December 2024}}{{cite web |title=Aegisub 3.4.2 Changelog |url=https://aegisub.org/changelog/3.4.2/ |date=12 January 2025}}

| latest release date = {{Start date and age|2025|1|12}}

| operating system = Windows, macOS, Linux and FreeBSD

| genre = Subtitles

| repo =

| programming language = {{wikidata|properties|normal+|linked|edit|P277}}

| license = 3-clause BSD License

| language = English, Czech, German, Spanish, Finnish, French, Hungarian, Italian, Japanese, Catalan, Brazilian Portuguese, Traditional Chinese, Simplified Chinese, Russian, Bulgarian, Serbian, Greek, Turkish

| language count = 18

| website =

}}

Aegisub is a subtitle editing application. It is the main tool used for fansubbing, the practice of creating or translating unofficial subtitles for visual media by fans.{{cite web |last1=Orsini |first1=Lauren |title=How American Fans Pirated Japanese Cartoons Into Careers |url=https://www.forbes.com/sites/laurenorsini/2015/06/24/how-american-fans-pirated-japanese-cartoons-into-careers/ |work=Forbes |access-date=14 December 2018 |language=en}} It is the successor of the original SubStation Alpha and Sabbu.

Aegisub's design emphasizes timing, styling of subtitles, and the creation of karaoke videos. It allows for many video processing bindings to process the timing, such as FFmpeg and AviSynth. It can also be extended with the Lua and MoonScript scripting languages.{{cite web|title=Automation|url=https://aegisub.org/docs/latest/automation/|work=User Manual Aegisub}}

The app's native subtitle format is Advanced SubStation Alpha, which supports subtitle positioning and styling. Aegisub can export subtitles to other common formats as well, such as SubRip's ".srt" format,{{Cite web |title=Adding Subtitles to Media |url=https://humtech.ucla.edu/instructional-support/using-video-ccle__trashed/adding-subtitles-to-media/ |access-date=2025-01-24 |website=HumTech - UCLA |language=en-US}} but at the cost of losing all other features except for raw text and basic timing.

In fansubbing, Aegisub is used when translating and interpreting languages, creating and adjusting timing, editing subtitles, typesetting, quality checking, karaoke lyric timing and karaoke text effects. However, different tools can be used to achieve the same effect, such as Adobe Premiere Pro for typesetting,{{Cite web |date=2019-05-30 |title=Automatic subtitle |url=https://community.adobe.com/t5/after-effects-discussions/automatic-subtitle/m-p/10472195 |access-date=2025-01-24 |website=community.adobe.com |language=en}} or a simple text editor like Notepad++ when providing translated text.{{Cite web |title=How To Create SRT Subtitles in 8 Steps (Plus Tips) |url=https://www.indeed.com/career-advice/career-development/srt-subtitles |access-date=2025-01-24 |website=Indeed Career Guide |language=en}}