How to extract subtitle from video using ffmpegwasm?

**Is your feature request related to a problem? Please describe.**
Would like to know if we can use ffmpegwasm to extract the embedded subtitle tracks

**Describe the solution you'd like**
A clear and concise description of what you want to happen.
ffmepg.run('-i', 'input.mp4', '-map', '0:s:0"', subs.srt);

**Describe alternatives you've considered**
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**Additional context**
Add any other context or screenshots about the feature request here.