Video to SRT: How to Generate Subtitle Files from Any Video

Key takeaways

• •AI generates .srt subtitle files from raw video — no manual audio extraction step.
• •Accepts MP4, MOV, MKV, WebM, AVI directly; max file size 5 GB on VexaScribe.
• •Output is timestamped, line-broken, UTF-8 encoded — drops into YouTube, Premiere, DaVinci, VLC, CapCut without conversion.
• •Accuracy 92-97% on clean audio; review proper nouns and technical terms before publishing.
• •Cost $0.20-$0.60 per video hour AI; $90-$300 per video hour human (Rev, 3PlayMedia).
• •Processing 5-15 minutes per video hour AI; 12-48 hours human turnaround.
• •Diarization is optional — useful for interviews and panels, irrelevant for single-speaker explainers.

How to convert video to SRT (4 steps)

1. 1

   Upload the video file

   MP4, MOV (iPhone default), MKV, WebM, AVI up to 5 GB per file (approximately 8-10 hours of compressed video). Audio is extracted from the video container automatically — no manual conversion to MP3 or WAV required. Free trial accepts the first 30 minutes of any file.

2. 2

   Choose source language and diarization

   Select source language from 99 supported languages, or use auto-detect for clean monolingual audio. Toggle speaker diarization on for multi-speaker video (interviews, panels, podcasts) — labels speakers as Speaker 1, Speaker 2 for renaming later. Diarization is included on every paid plan with no tier gating.

3. 3

   Wait for processing

   AI runs at 4-10× real-time. A 30-60 minute video processes in 5-15 minutes. VexaScribe emails you when the SRT is ready. While waiting, you can queue additional video uploads — useful for batch caption generation across a YouTube channel or course.

4. 4

   Download the .srt and review

   Download the .srt file (UTF-8 encoded, timestamped, line-broken to ~42 chars/line). Quick proofread for proper nouns, brand names, technical terms (5-15 min/hr). Drop into YouTube Studio (Subtitles → Upload file), Premiere Pro (Captions panel → Import), DaVinci Resolve, CapCut, or VLC. DOCX and TXT also exported for downstream workflows.

Supported video formats

VexaScribe accepts the most common video containers directly — no manual audio extraction step. The platform extracts the audio track using ffmpeg internally and routes the audio through the Whisper Large-v3 transcription pipeline.

Max file size: 5 GB per upload — covers approximately 8-10 hours of typical compressed video at 720p-1080p. For longer files, split with a free tool like LosslessCut before uploading.

Self-hosted Whisper users must extract audio first since base Whisper accepts only audio formats: ffmpeg -i input.mp4 -vn -acodec libmp3lame audio.mp3, then whisper audio.mp3 --output_format srt.

What is an SRT file?

SRT (SubRip Subtitle) is the universal subtitle format — a plain UTF-8 text file with numbered subtitle blocks. Each block contains an index, a timestamp range, and one or more lines of text. Universally supported: YouTube, Vimeo, Premiere Pro, DaVinci Resolve, CapCut, VLC, Windows Media Player, every social platform, and every streaming service.

1
00:00:00,000 --> 00:00:03,500
Welcome to the introduction lecture.

2
00:00:03,500 --> 00:00:07,200
Today we'll cover three main topics.

3
00:00:07,200 --> 00:00:11,800
Let's start with the first one.

Anatomy of a block:

• →Index: sequential integer starting at 1. Must be unique and ordered.
• →Timestamp range: HH:MM:SS,mmm --> HH:MM:SS,mmm. Note the comma (not period) before milliseconds — common cross-platform compatibility issue.
• →Text lines: one or two lines per block. Broadcast standard caps at 42 characters per line; mobile-friendly drops to 32-36.
• →Blank line: separates each block. Critical — missing blank lines break parsing in some players.
• →Encoding: UTF-8 without BOM is the safe default. UTF-8 with BOM works in most players but trips a few legacy ones.

SRT vs VTT? SRT is the default for nearly every workflow. VTT (.vtt, WebVTT) is HTML5 video's native caption format with extra styling support (positioning, colors, font, regions) — use VTT only when those styling features matter for a custom HTML5 video player. For YouTube uploads, SRT is standard; YouTube auto-converts internally.

Accuracy by video type

Whisper Large-v3 (the model VexaScribe uses) hits 95-97% accuracy on clean single-speaker video but degrades predictably with audio conditions. Plan your review time based on the type of video you're subtitling.

Where AI consistently misses: proper nouns (brand names, product names, technical terms) at 20-30% error rate even on clean audio; numbers spelled vs digits ("twenty twenty six" vs "2026"); homophones (their/there/they're); rapid-fire counts and lists. Always proofread before publishing public-facing captions.

For accuracy methodology, see how accurate is Whisper? with WER benchmarks across LibriSpeech and FLEURS.

Cost: per-video and bulk math

AI subtitle generation is genuinely cheap — typically $0.20-$0.60 per video hour on consumer apps. Human captioning is 150-1,500× more expensive. The cost math only flips toward human if you specifically need verbatim, court-grade, or ADA-certified broadcast captions.

Bulk math example: a YouTube channel publishing 4 videos/month at ~15 minutes each = 1 hour of new video monthly. SRT generation costs $0.20-$0.60 on AI versus $90-$300 with human captioning — a 150-1,500× difference. For a 40-episode course (~20 hours of video total), AI runs $4-$12 versus $1,800-$6,000 human.

For full cost analysis across the 14-tool transcription market, see how much does transcription cost? with verified 2026 pricing and an interactive calculator.

Multi-language SRT (99 languages)

VexaScribe supports SRT generation in 99 languages via Whisper Large-v3, including all major European, East Asian, and Middle Eastern languages — Spanish, French, German, Italian, Portuguese, Japanese, Korean, Mandarin, Arabic, Russian, Hindi, Turkish, Vietnamese, Polish, Dutch, Swedish, plus 83 more. Source language is auto-detected from the audio or manually selectable.

Common workflows: Spanish-language creator generates Spanish SRT for native audience plus English SRT for international viewers. Japanese tutorial creator generates Japanese + English + Spanish SRTs for global reach. Documentary filmmaker generates SRTs in source language plus festival-circuit target languages (English, French, German). See also transcribe and translate audio.

Common SRT errors and fixes

Most SRT problems come from one of five issues. Here's how to recognize and fix each one.

Recommended free editor: Subtitle Edit (Windows) — handles framerate conversion, line balancing, encoding fixes, sync drift, and translation memory in one tool. For cross-platform editing, Aegisub. For quick edits, the built-in caption editors in YouTube Studio, Premiere Pro, and DaVinci Resolve all work.

Video to SRT vs alternatives

We position VexaScribe honestly: it's the right pick for most batch SRT workflows (direct video upload, 99 languages, speaker labels, $2/mo entry). Other tools win specific lanes — here's the honest read.

When to pick something other than VexaScribe. If you're editing the video and need captions integrated with the editor, Descript is the right call — the caption editor sits inside the video editor. If your channel is English-only and you don't care about accuracy quality, YouTube auto-captions are free and require zero workflow steps (the captions appear automatically after upload). If you have technical skills, a GPU, and high-volume needs, self-hosted Whisper is free forever — pay the setup cost once, run unlimited.

See also SRT generator (format deep dive) and transcription tool alternatives.

Embedding the SRT in your video

Once you have the .srt file, embedding it is straightforward. Quick reference for the most common destinations:

For step-by-step embedding tutorials across platforms (including iPhone, Final Cut Pro, and burning subtitles permanently into video), see how to add subtitles to a video.

FAQ

Methodology & disclosure