AI Segmentation & Quota
Two separate AI features on the Video Subtitles screen — re-cutting caption lines into sentences, and generating subtitles for a video that has none.
Two things on this screen both say "AI" and are often mistaken for each other. They solve different problems, cost different resources, and one of them makes the other unnecessary.
| AI smart segmentation | AI subtitles quota | |
|---|---|---|
| Needs | An LLM provider that can generate text | A signed-in Pro or Ultra account |
| What it uses | Your provider's tokens | Transcription minutes from your plan |
| What it does | Re-cuts captions the video already has | Produces captions for a video with none |
| Where | A switch under Basics | A usage panel, plus a button in the player |
AI smart segmentation
YouTube's auto-generated captions arrive as word-level fragments, each with its own start and end time. Read Frog can regroup them with rules alone, but on a talkative video the result still breaks mid-clause.
With AI smart segmentation on, those fragments are sent to your LLM provider, which returns them re-cut into complete sentences — punctuated and capitalised — and assigns each new line a start and end time taken from the first and last word it contains.
That timing is the trade-off. The model is deriving timestamps, not reading them off a clock, so lines can land slightly early or late, and a line that was easy to follow can drift out of sync. Turn it off if the captions stop matching the speech.
Concretely, with it on:
- Captions are cut into sentences rather than at arbitrary word boundaries, which also gives the translator whole sentences to work with.
- Each look-ahead window is one extra model request, so it costs tokens and adds latency before captions appear.
- It needs a provider that can generate text. On Google Translate or DeepL the switch has no effect and the rule-based cut is used instead.
- It does nothing to captions that already come as sentences. Some YouTube tracks do, and AI-generated subtitles always do.
The switch is off on a fresh install, and it is under Options → Video Subtitles → Basics.
AI subtitles quota
This is speech recognition, not translation. When a video has no captions at all — or only ones you would rather not read — the Request AI subtitles control in the player's Read Frog settings sends the video off to be transcribed, and the result comes back as a subtitle track Read Frog can then translate like any other.
It needs you signed in, and it needs a Pro or Ultra plan. Transcription is metered in minutes, and the panel on the settings screen shows what you have left: one bar per pool, labelled with the date the monthly quota resets, or the date a one-time grant expires.
Read Frog checks entitlement before it switches tracks, not after, so a refusal does not destroy the captions you were already watching. What you see depends on what is missing:
| Situation | What happens |
|---|---|
| Not signed in | A toast with a log-in button; the panel shows the same |
| Signed in, no subscription | A toast with an upgrade button |
| Minutes used up | A toast naming the date your quota comes back |
| Video too long | A toast saying so, with no button — no plan changes this |
| Still transcribing | A toast asking you to click again in a few minutes |
A request runs in the background and can take a few minutes on a long video; the player shows it as loading meanwhile. If you give up waiting, the transcription keeps running on the server and the result is kept, so clicking again resumes the same job rather than starting a second one.
AI subtitles come back already cut into sentences, so AI smart segmentation is skipped for them entirely. The two features never run on the same track.
Clear AI segmentation cache
A segmentation result is stored the first time it is produced, keyed to the caption fragments and the provider that cut them, so replaying a video you have already watched costs nothing.
Clear AI segmentation cache, at the bottom of the Video Subtitles screen, throws that store away. It asks for confirmation and cannot be undone. Reach for it when segmentation produced timings you want re-derived, or after switching to a provider whose cuts you expect to be better — otherwise the stored result is what you keep seeing.
It is a separate store from the translation cache on the Translation Control screen. Clearing one leaves the other alone, and neither touches your providers, prompts, or styles.
Where to go next
Everything else about subtitles — enabling them, the provider, auto-start, display and request pacing — is in Video Subtitles. The prompt the translation itself uses is in Subtitle Prompts.