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Subtitle Machine

An internal tool for a tech company, turning raw video into correct captions in minutes.

Type
AI tool + web app
Timeline
Built 2026
Role
Design & build, end to end
Status
Client · live
GreenfieldAIMarketing Videos / AI Agents Launch.mp4✓ Saved↺↻⚠ 8 issues⚑ Glossary⧉ Quick fixes⬇ Export .srt
✦
there's an agent for just about anything
▶
0:27 / 0:39
0.5×0.75×1×1.5×2×
↻ Loop cue
Subtitles4 errors4 warnings
10:00.1–0:02.1Managing it all yourself?
In−100ms0:00.1+100ms← Set to playheadSplitMergeInsertDelete
20:02.2–0:04.0Meet Greenfield AI's new agents
30:04.1–0:05.4this July
40:06.3–0:07.8It's Monday morning
50:07.9–0:09.0Hundreds of tasks,
60:09.1–0:10.2dozens of requests,17.3 CPS
70:10.3–0:12.2and a team that needs direction?17.0 CPS
80:12.2–0:14.3Good thing there's an agent for that17.8 CPS
90:14.3–0:15.5Not sure what still needs25.1 CPS
100:15.6–0:17.2to be taken care of?19.6 CPS
110:17.2–0:19.2There's an agent for that
120:19.3–0:20.5Worried your backlog22.2 CPS
130:20.6–0:22.3is starting to slip?
140:22.4–0:24.5Yeah, there's an agent for that
150:25.3–0:26.1In fact,0.8s
160:26.2–0:29.0there's an agent for just about anything
170:29.1–0:30.1And when there isn't,20.2 CPS
180:30.2–0:31.5just let us know
190:34.0–0:34.9Greenfield AI
200:35.0–0:36.0The AI platform
210:36.1–0:38.3for the future of work
GreenfieldAI⚠ 8⬇ .srt
✦
there's an agent for just about anything
160:26.2–0:29.0there's an agent for just about anything
20:02.2–0:04.0Meet Greenfield AI's new agents
30:04.1–0:05.4this July
40:06.3–0:07.8It's Monday morning
50:07.9–0:09.0Hundreds of tasks,
60:09.1–0:10.2dozens of requests,17.3 CPS
70:10.3–0:12.2and a team that needs direction?17.0 CPS
80:12.2–0:14.3Good thing there's an agent for that17.8 CPS
90:14.3–0:15.5Not sure what still needs25.1 CPS
100:15.6–0:17.2to be taken care of?19.6 CPS
110:17.2–0:19.2There's an agent for that
120:19.3–0:20.5Worried your backlog22.2 CPS
130:20.6–0:22.3is starting to slip?
140:22.4–0:24.5Yeah, there's an agent for that
150:25.3–0:26.1In fact,0.8s
160:26.2–0:29.0there's an agent for just about anything
170:29.1–0:30.1And when there isn't,20.2 CPS
180:30.2–0:31.5just let us know
190:34.0–0:34.9Greenfield AI
200:35.0–0:36.0The AI platform
210:36.1–0:38.3for the future of work
The problem

Captioning a marketing video is mind-numbing work, and auto-generated captions haven't solved it. They get names wrong, leave in every um and false start, and don't understand the business's. Someone still fixes it all by hand.

The approach

So I built a tool that does the editorial work automatically, not just the transcription.

01

Times every word exactly with a speech-to-text pass

02

Strips filler and false starts, rewrites for natural reading

03

Checks every term against the house glossary for the business

04

Applies house style rules per video size, square or widescreen

05

Live editor for fixing anything left, video and captions side by side

The part I love

The brand guardian

Every business has its own words for its own things, and generic captioning tools have no way to know them.

The tool sets its own guidelines per video, sized to fit, and runs a brand guardian alongside the cleanup pass. It checks every name against the glossary and fixes mistakes. The guardian has final say on names that matter.

The outcome
93% faster
to produce subtitles per video
96% cheaper
than previous AI tool
Almost zero
corrections needed

Live since June 2026, and the team hasn't looked back.

AIVideoAutomation

This is an internal tool with no public URL. Happy to walk you through it live.

Let's build

Have a problem worth solving?

I usually reply within a day.