Download http://www.aegisub.org/downloads/
- Run Aegisub
- Load the video: Video > Open Video
- Scroll video to the correct position in the Player window.
- Then scroll to that time in the Audio Spectrum window.
- Now highlight the area of the text to add subtitles in the Spectrum Window.
- In the textfield below, enter the subtitles, then hit ENTER. This will add the subtitle IN and OUT and TEXT in the lines below.
- The Audio spectrum automatically moves to the next LINE of speech, and you can use the BLUE play button there to hear the automatic selection, and adjust accordingly, before repeating step 6.
HINT: Click on the lines below the Player, to scroll the Player window to the correct position for playback and preview.
If you need to convert the completed ASS file to SRT, use:
http://sourceforge.net/projects/ass2srv/