Generate Subtitles for Any Raw Video File

~982hours

of listening to reach N1

Based on your settings below. Adjust the calculator to customize.

N2
Yearly Journey53% Complete

By Dec 31, 2026, you'll have immersed for 525 hrs at this pace.

Language & Levels

N2

N2 (Pre-Advanced)

N1

N1 (Advanced/Fluency)

Study Parameters

How closely related is this to languages you already know?

1.5 hrs
0.5 hr8 hrs

Method & Goals

Reading-While-Listening boosts input efficiency (1.4x speed).

Active Fluency requires +25% time for output/speaking drills.

Expert NoteKanji acquisition is a marathon. Grammar is distinct (SOV) and highly agglutinative.
YouTube: 655 hoursPodcasts: 327 hours982HOURS
Est. CompletionOctober 2027

Media Breakdown

~3,930 videos
~0 episodes
~436 episodes
~0 movies
~0 books
Efficiency Savings
-393 hrs

* Average Lengths: YT (10m) • TV (24m) • Podcast (45m) • Film (100m) • Book (300m)

Generate Subtitles for Any Raw Video File

Don't let a lack of subtitles stop your immersion. SubSmith uses local Whisper AI to transcribe raw Japanese audio into perfect synced subtitles.

💡 Key Insight: Accessing raw content (interviews, un-subbed anime, YouTube) is the final frontier of immersion. AI transcription removes the language barrier.

Key Numbers

95%+
Accuracy

Large-v3 model support for near-human level transcription.

Source: OpenAI Whisper
100% Local
Privacy

Your files never leave your computer. No API costs.

Source: Offline Engine
Auto-Align
Sync

Generates timestamps automatically based on audio waveforms.

Source: Timeline AI

No Subtitles? No Problem.

As you advance to N1, the content you want to consume often has no subtitles. Raw talk shows, niche YouTubers, or older dramas often lack official caption tracks.

The Old Way: Search shady subtitle sites, find a desynced .SRT file, spend 20 minutes manually shifting the timing in VLC, and still have it drift out of sync.

The SubSmith Solution: Open the raw video file. Click "Transcribe." SubSmith runs a local instance of Whisper AI (accelerated by your GPU) to generate a subtitle track in minutes. It is basically magic for raw immersion.

Feature Spotlight: One-Click Mining. These AI-generated subtitles work just like normal ones. You can hover to look up words, and click to mine sentences to Anki. You can turn "un-learnable" raw content into a goldmine of vocabulary.

Frequently Asked Questions

Does it require a GPU?

A GPU is recommended for speed, but SubSmith includes a CPU-optimized mode that works on any modern computer (Mac M-series supported).

How much does it cost?

SubSmith manages the Whisper model download and execution for you locally. There are no per-minute cloud fees like other services.

Learn more: The Math of Fluency · Science of Subtitles · Comprehensible Input

The Science Behind the Math

This calculator isn't a random guess. It's built on 70+ years of linguistic research from the U.S. FSI, academic studies on vocabulary acquisition, and modern immersion efficiency data. Read the full deep dive.

Base Hours: FSI Standard

We use the Foreign Service Institute (FSI) difficulty rankings as our baseline. The FSI has trained US diplomats for decades, gathering precise data on class hours required for proficiency.

  • Category I (e.g. Spanish): ~600-750 hours
  • Category V (e.g. Japanese): ~2200 hours
Note: FSI figures assume "classroom hours" + equal self-study. We adjust this base to reflect total immersion time required for an independent learner.

Efficiency: Reading-While-Listening

Dr. Paul Nation's research (Victoria University of Wellington) on the "Four Strands" of language learning highlights the power of bi-modal input.

Combining audio with matching text (RWL) creates a 1.4x efficiency boost in vocabulary retention compared to listening alone. It bridges the gap between the high retention of reading and the natural flow of listening.

Why the "Active Fluency" Penalty?

The "Silent Period" Reality

Linguistic research consistently shows that receptive fluency (understanding) always precedes active fluency (speaking). Children understand language months before they speak.

Our Calculation (+25%)

Bridging the gap from "Input Only" to "Active Fluency" requires output drills (speaking/writing). We add a conservative 25% time surcharge to account for this necessary activation energy.

Key Research Sources:

Ready to Start Your Immersion Journey?

SubSmith helps you transcribe your favorite media and create study materials for true immersion learning.

Download SubSmithWhy Subtitles Work →