How to Batch Subtitle Your Entire Collection Overnight

You've got a folder full of Japanese videos with no subtitles. Doing them one at a time would take forever. The good news: JAVSubs has batch processing built in. Queue up everything, hit start, and come back to fully subtitled content.

Here's exactly how to do it — plus tips to get the best speed out of your hardware.

Step 1: Prepare Your Files

Before you start, a little organization goes a long way:

• Put all videos in one folder — or at least know where they are. JAVSubs accepts files from anywhere, but it's easier to drag a batch from one location.
• Check disk space — you'll need roughly 2 GB of free space per video for temporary files during processing. The final .srt files are tiny (a few KB each), but the intermediate audio extraction needs room.
• Supported formats: MP4, MKV, AVI, MOV, WebM, M4V, WMV — basically anything with a Japanese audio track.

Step 2: Configure Your Output Directory

Open JAVSubs and go to Settings. Set your output directory — this is where all the generated .srt files will land. By default it's Videos/Subtitles in your home directory.

If you want subtitles burned directly into the video files (hardcoded), toggle "Burn Subtitles" on. Keep in mind this creates a new copy of each video, so you'll need a lot more disk space.

Step 3: Queue Your Videos

There are two ways to add videos to the queue:

1. Drag and drop — select multiple files in your file manager and drag them onto the JAVSubs window. All of them get added to the queue at once.
2. File picker — click the add button and select multiple files using your system's file dialog (hold Ctrl/Shift to select multiple).

You'll see all queued files listed with their status: Pending, Processing, Complete, or Error.

You can remove individual files from the queue before they start processing, or clear all pending items at once.

Step 4: Start the Queue

Hit the Start Queue button. JAVSubs processes videos one at a time — here's what happens for each:

1. Audio extraction — ffmpeg pulls the audio track from the video
2. Transcription — Whisper large-v3 transcribes the Japanese audio to text
3. Translation — a specialized JA→EN model translates the text to natural English
4. SRT generation — timed subtitle file is written to your output folder
5. Burn (optional) — if enabled, subtitles are hardcoded into a new video file

The progress bar shows you which file is currently processing and how far along it is. Then it automatically moves to the next one.

How Long Will It Take?

Processing time depends on your hardware and video length. Here are rough estimates for a 2-hour video:

Hardware	Time per 2hr Video	10 Videos Overnight
NVIDIA RTX 4070+ (10GB+ VRAM)	~5-8 minutes	~1 hour
NVIDIA RTX 3060/3070 (8GB+ VRAM)	~8-12 minutes	~1.5 hours
AMD RX 6700+ (Vulkan)	~10-15 minutes	~2 hours
CPU only (modern 8-core)	~30-60 minutes	~5-8 hours
CPU only (older/4-core)	~60-90 minutes	~10-15 hours

Even on a CPU-only machine, you can easily process 10+ videos overnight. Queue them up before bed, and they'll be done by morning.

Tips for the Best Batch Processing Experience

Close other GPU-heavy apps

Games, video editors, and even browsers with hardware acceleration use VRAM. Close them before starting a big batch to give JAVSubs full access to your GPU. JAVSubs needs at least 5 GB of free VRAM to use GPU acceleration — if less is available, it falls back to CPU mode automatically.

Disable sleep and hibernation

Nothing worse than waking up to find your computer went to sleep after 30 minutes. On Windows, go to Settings → System → Power and set "Sleep" to Never while batch processing. On Linux, use systemctl mask sleep.target or your DE's power settings.

Let your screen lock, but don't let the system sleep

Screen lock is fine — it doesn't stop processing. System sleep or hibernation will kill the queue. There's a difference.

Check results in the morning

When the queue finishes, JAVSubs sends a system notification ("Batch processing complete!"). You can also check the Processing History to see which files succeeded and which had errors.

Handle errors gracefully

If a video fails (corrupted file, no audio track, etc.), JAVSubs skips it and moves to the next one. It won't stop your entire batch. Check the history afterward for any failures.

Long Videos? JAVSubs Handles Them Automatically

Videos longer than 12 minutes are automatically split into 10-minute chunks for transcription. This improves accuracy — Whisper performs better on shorter audio segments. The chunks overlap by 30 seconds so nothing gets lost at the boundaries.

You don't need to do anything. It's all handled automatically. A 3-hour video gets split, transcribed in chunks, and merged back into a single clean .srt file.

After Processing: Where Are My Subtitles?

All generated subtitle files go to your configured output directory. For each video, you get:

• filename.en.srt — English subtitles (this is the one you want)
• filename.ja.srt — Japanese transcription (useful for language learners)
• filename_subtitled.mp4 — video with burned-in subs (only if "Burn Subtitles" is enabled)

To use the .srt files, just put them in the same folder as your video with the same name. Most video players (VLC, MPV, MPC-HC, PotPlayer) will auto-detect and load them. See our guide on how to use SRT subtitles in any video player for details.

The Bottom Line

Batch processing in JAVSubs is dead simple: queue files, hit start, walk away. Whether you've got 5 videos or 50, the workflow is the same. GPU users can churn through a large collection in a couple of hours. CPU users can let it run overnight.

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