← captionREFLOW

captionREFLOW User Manual

Version: Beta v1.0

Updated: July 22, 2026

captionREFLOW helps you turn an SRT caption file into cleaner, readable captions and, when needed, align caption breaks to your video's edit points.

Reflow is rule-based. It does not use AI, does not transcribe, does not rewrite your words, and does not change the source timing. Snap to Cuts is the optional server-side step that uses your video to align caption boundaries to visual cuts.

Quick Start

  1. Open captionREFLOW.
  2. Choose whether to keep "Reflow captions before Snap to Cuts" turned on.
  3. Upload or paste an SRT file.
  4. Choose the aspect ratio outputs you need.
  5. Review the reflowed captions.
  6. Optional: run Snap to Cuts with a local video file.
  7. Preview the captions over video.
  8. Download the finished SRT files.

Basic Workflow

The main workflow has four steps:

  1. SRT Upload & Setup
  2. Reflow
  3. Snap to Cuts
  4. Preview

You can move through the steps with the Next and Back buttons. If a step is locked, complete the earlier required step first.

Step 1: SRT Upload & Setup

Use Step 1 to provide your source captions and choose your output setup.

You can upload an .srt file or paste SRT text directly into the app. If you upload a file, captionREFLOW reads it in your browser for Reflow. Reflow does not upload your SRT.

Reflow Captions Before Snap to Cuts

This option is on by default.

When it is on, captionREFLOW creates cleaner, phrase-aware captions before Snap to Cuts. This is useful when your source SRT is word-by-word, overly dense, or awkwardly line-broken.

When it is off, captionREFLOW keeps your source captions exactly as-is and sends that source SRT to Snap to Cuts if you run Snap.

Aspect Ratios

Choose the aspect ratios you need:

  • 16:9
  • 1:1
  • 4:5
  • 9:16

captionREFLOW generates separate SRT outputs for the selected aspect ratios. At least one aspect ratio remains selected.

Line Style and Character Limits

For each aspect ratio, choose one-line or two-line captions and set a maximum character count. These settings affect the reflowed caption structure, not the words themselves.

Broadcast Guideline Preset

Broadcast Guideline Preset is optional and appears only when Reflow captions before Snap to Cuts is turned on.

When enabled, it creates a single 16:9 broadcast-style output using the selected preset where available. Some broadcasters may be listed as coming soon and are not applied yet.

Presets are practical guides for line count, line length, safe area, and preview styling. They are not a compliance guarantee.

The list covers three kinds of preset:

  • Broadcaster presets, taken from a broadcaster's own published subtitle or caption guidance.
  • Streaming platform presets, such as Prime Video and Warner or Max, taken from that platform's delivery guide. These are platform guides, not broadcast delivery specifications.
  • A format starter, CEA-608 / SCC, whose 32 characters per line comes from the limits of the format itself rather than from any broadcaster's editorial rule.

A broadcaster stays listed as coming soon when the public material we found is not enough to derive a verified editorial preset. Some documents are delivery-only, some are viewer-accessibility-only, some are scoped to advertising or to older guidance, and some broadcasters are not publicly documented in enough detail. Selecting one explains why and does not apply anything.

A document can be very detailed about file format and timecode and still say nothing about how long a caption line should be, which is what a reflow preset needs.

Where a preset lists a preferred length that is tighter than its maximum, the preset uses the maximum. Turn on Override preset settings if you want the tighter value.

What a preset sets

Once you pick a preset, a short summary line shows the guideline values that preset carries, for example: 2 lines, 37 characters per line, a 160 to 180 words-per-minute reading-speed guide, and a 75 percent safe width. A preset can affect three things:

  • Reflow settings. Line count and maximum characters per line are applied to the 16:9 output. Turn on Override preset settings if you want to edit them yourself.
  • Preview styling. The Step 1 sample frame and the Step 4 preview use the preset's safe area and placement guidance where the preset publishes them. Presets without their own values use a general broadcast safe area.
  • A guideline check. See below.

Reading speed, duration, gap, and shot-change values are guidance for your review. They never change your caption timing.

Guideline check

When a preset publishes reading-speed or duration guidance in seconds, Step 2 shows a short advisory line under the reflowed captions, for example: 4 cues over 20 cps, 2 cues under 1 second.

This is a read-only count to help you review. captionREFLOW never retimes, shortens, or rewrites captions to satisfy it. If a count looks high, the usual fixes are adjusting your line settings or editing the source captions before reflowing.

Some guideline rules are written in frames rather than seconds, such as minimum durations, short gaps measured in frames, and shot-change windows. Those depend on the frame rate of your delivery, so they are carried as guidance only and are not counted. Presets whose rules are all frame-based show no guideline check.

What an SRT can and cannot carry

An exported SRT contains caption text and timing only. It cannot carry positioning, regions, colours, speaker colours, roll-up or pop-on mode, or broadcast delivery formats such as SCC, EBU STL, EBU-TT, TTML, or embedded 608 and 708 data. Broadcast delivery in those formats needs a dedicated export and validation step, which captionREFLOW does not currently provide.

Step 2: Reflow

Step 2 shows your source captions and the reflowed result.

Reflow keeps the original words in order. It does not invent, remove, dedupe, or rewrite caption text. It only regroups existing caption words into cleaner captions using deterministic rules.

If Reflow captions before Snap to Cuts is off, Step 2 prepares the source SRT as-is so Snap to Cuts and Preview can use it.

Step 3: Snap to Cuts

Snap to Cuts aligns caption breaks to your video's visual edit points.

Snap to Cuts is optional. It requires:

  • a signed-in account with Snap to Cuts access;
  • a prepared SRT from Step 2;
  • a local video file.

Snap to Cuts uploads the selected local video and the prepared SRT only when you press Start Snap to Cuts. It runs on captionREFLOW's server-side processing system and returns snapped SRT outputs.

Continuous Speech Option

The Avoid snapping across continuous speech option skips visual cuts where the audio appears to continue through the edit.

This option works best with dialogue-only reference audio. Music beds, effects, or mixed program audio can make continuous audio harder to interpret. Leave the option off if you want Snap to Cuts to consider all detected visual cuts.

Progress and Downloads

While Snap to Cuts runs, each selected aspect ratio shows job progress. When an aspect finishes, you can download its snapped SRT from Step 3 or preview it in Step 4.

If all selected aspects finish, the panel shows that all aspects are snapped.

Express Snap to Cuts

Express Snap to Cuts is the fast path for users who already have a finished SRT and do not need the full Reflow and Preview workflow.

Use Express Snap to Cuts when you want to:

  • provide an SRT as-is;
  • provide a local video file;
  • run Snap to Cuts;
  • download the snapped SRT.

Express Snap to Cuts uses the same server-side Snap to Cuts job system as the main workflow.

Step 4: Preview

Step 4 lets you inspect captions over a video-shaped preview.

You can:

  • upload a local video for preview;
  • use a direct browser-playable video URL for preview;
  • switch between selected aspect ratios;
  • adjust caption size and vertical position;
  • compare Source vs Snapped or Reflowed vs Snapped when a snapped track exists;
  • download reflowed and snapped SRT outputs.

Local video selected in Snap to Cuts is shared with Preview so you do not need to choose the same video twice. Direct video URLs in Preview are preview-only and are not used for Snap to Cuts.

Snapped Cut Markers

When Snap to Cuts moves caption boundaries, Preview can show snapped cut markers on the seek bar.

Markers park the playhead one frame before the cut. Click a marker, then step forward one frame to inspect whether the caption boundary and video cut happen together.

The transport controls include:

  • previous snapped cut marker;
  • step back one video frame;
  • step forward one video frame;
  • next snapped cut marker;
  • play or pause.

Downloads

Download buttons appear when outputs are available.

Depending on your workflow, you may see:

  • Download Reflowed SRT;
  • Download Snapped SRT;
  • Download All Reflowed SRTs;
  • Download All Snapped SRTs.

Downloaded SRT timing is product output. Preview-only display compensation never changes downloaded files.

Accounts and Beta Access

Reflow works with or without an account.

Snap to Cuts requires a signed-in account because it uses server-side video processing, storage, queue capacity, and usage limits.

During beta, Snap to Cuts is free for signed-in users who activate beta access. Email-and-password accounts may need email verification before beta access works.

Signed-in users can see daily and monthly Snap to Cuts usage. Fair use is 10 jobs per day and 100 per month per account during beta. If beta access is paused for new users, existing users with access can keep working.

Feedback and Troubleshooting

Use Send feedback to report issues or request improvements.

Troubleshooting file sharing is optional and off by default. If you opt in, captionREFLOW can share limited troubleshooting artifacts for the issue you are reporting.

For Snap to Cuts issues, this may reference files already associated with a Snap job. For Reflow issues, this may include source and reflowed SRTs from your current browser session only if you explicitly choose to share them. You can also attach a small number of allowlisted support files.

Privacy and File Handling

Reflow runs in your browser and does not upload your source SRT.

Snap to Cuts uploads your video and prepared SRT only when you press Start Snap to Cuts. Those files are used to produce your snapped SRT and are set to expire about 24 hours after processing.

Feedback troubleshooting artifacts are opt-in. Files shared for troubleshooting are set to expire about 24 hours after submission.

No AI or third-party language model touches your captions or video.

Known Beta Limits

  • This is an early beta. Expect rough edges.
  • Snap to Cuts needs a local video file and a clean source SRT.
  • Shorter source cues give Snap to Cuts better caption boundaries to align.
  • Exported timing follows a Premiere-friendly convention. If you import into a different NLE, sanity-check the first few boundaries.
  • Broadcast presets are practical guides, not compliance guarantees.

Prefer a file? Download the PDF.