Extracting subtitles from MPEG files

ccextractor is an open source tool to extract subtitle tracks.

To install it via brew:
brew install ccextractor

To extract the default (English) subtitle to default (SRT) format, just use
ccextractor video.mp4

To extract all subtitles from all m4v files in the current directory (.):
find . -name "*.m4v" -exec ccextractor {} \;