Subtitle & Caption Studio

Subtitles assume the viewer can hear the audio but needs language assistance (e.g., foreign language translation or dialogue transcription). Captions (Closed Captions) are designed for deaf or hard-of-hearing viewers and include essential non-speech audio information, such as speaker identifiers, sound effects (e.g., [Door slams], [Laughter]), and musical cues.

SRT (SubRip Subtitle) is the most widely supported plain-text subtitle format. It consists of sequential cue numbers, timecodes formatted as HH:MM:SS,mmm --> HH:MM:SS,mmm, subtitle text, and blank separating lines. While highly compatible, standard SRT does not support advanced positioning or styling.

WebVTT (Web Video Text Tracks) is the W3C standard format for HTML5 <video> elements. Files start with a 'WEBVTT' header, use periods for millisecond delimiters (00:00:00.000), and natively support cue settings for positioning, alignment, line placement, and vertical orientation.

The main differences are: 1) WebVTT requires a 'WEBVTT' header; 2) SRT uses commas for milliseconds (00:01:23,456) while WebVTT uses periods (00:01:23.456); and 3) WebVTT supports cue settings (align:center line:85%) and CSS styling, whereas standard SRT is purely text and timing.

ASS is a rich subtitle format popular in anime fansubbing and karaoke. It supports vector drawing, custom fonts, borders, shadows, precise screen positioning (\pos), rotations, and color overrides.

SSA is the predecessor to ASS (ScriptType v4.00). It introduced structured style headers and margin configurations that were later expanded in ASS.

SBV (SubViewer) is a simple subtitle format used by YouTube for caption uploads and downloads. It features timestamp lines formatted as 0:00:01.000,0:00:04.000 followed by text.

Yes. You can edit text, tweak start/end timestamps, add, delete, duplicate, reorder, renumber, and run find-and-replace across all cues directly in your browser.

Yes. Video is completely optional. You can create subtitles from scratch or import existing files to edit, inspect quality, synchronize, and export without any video.

Yes. When you load a local video, playback time synchronizes with the timeline and editor. Clicking any cue seeks the video to that moment, and the timeline allows dragging cues to align them with dialogue.

Yes. The Global Shift tool offsets all cues forward or backward by your specified milliseconds (e.g. +1500ms or -500ms), with automatic clamping to prevent negative timestamps.

Two-Point Sync is a linear time retiming method. You set target timestamps for an early cue (Anchor A) and a late cue (Anchor B). The engine calculates a linear scale factor and offset (y = ax + b) to automatically stretch or compress all cues, fixing gradual audio drift in one step.

Yes. The FPS Retiming tool scales subtitle cue timestamps based on source and target frame rates (such as 23.976fps to 25fps or 29.97fps to 24fps). Note that this retimes subtitle timings only and does not transcode the video.

An overlap occurs when a cue starts before the preceding cue finishes (e.g., Cue 1 ends at 00:03.000 but Cue 2 starts at 00:02.500). In many players, this causes visual collisions or flickering.

A gap is the silent interval between the end of one cue and the start of the next. While natural during dialogue pauses, extremely short gaps (< 50ms) can cause screen readers and renderers to stutter.

CPS measures reading speed. It divides character count by cue duration in seconds. Industry standards generally recommend keeping CPS between 15 and 21 characters/sec to ensure viewers can comfortably read the caption while watching the video.

Yes. The Auto Wrap feature formats text to a specified maximum character width (e.g. 37 chars), splitting cleanly on word boundaries for English and respecting punctuation marks for Japanese and Chinese.

Yes. The engine uses modern Unicode grapheme segmentation (Intl.Segmenter) to correctly handle multi-byte characters, emoji sequences, zero-width joiners, and international scripts without corruption.

No. All parsing, validation, retiming, and serialization are executed 100% locally in your browser's JavaScript memory. Zero subtitle text is ever sent over the network.

No. Local video playback uses the standard HTML5 File API and object URLs (blob:). The video data stays strictly on your computer.

No. In strict accordance with Solasu's privacy rules, data is not saved to localStorage, sessionStorage, IndexedDB, or cookies. Closing the tab immediately clears all data from memory.

Yes. Subtitle Studio provides both a custom overlay renderer and native HTML5 <track> integration so you can preview how your captions appear across standard players.

Yes, because different formats support different feature sets. For example, converting ASS to SRT drops font colors and coordinates because SRT does not support styling. Subtitle Studio provides an explicit Format Loss Report detailing all preserved and dropped attributes.

Dialogue text, speaker names, and timing are preserved, but ASS style override tags (\pos, \an, \fad), font definitions, and outline colors are omitted to produce standard SRT output.

No. We deliberately avoid artificial scores like '88/100'. Instead, the Quality Inspector presents objective observations (overlaps, high CPS, line lengths, Unicode flags) with supporting evidence and limitations.

No. Readability depends on viewer literacy, screen distance, display size, and audience age. The studio highlights industry-standard benchmarks without claiming absolute readability guarantees.

Browsers only support specific video containers and compression codecs (such as H.264, VP9, or AV1 in MP4/WebM). If a file uses an unsupported codec (like ProRes or HEVC on older browsers), the browser cannot decode it without native OS support.

Yes. The interface is fully responsive down to 375px viewport widths. For extensive subtitle editing and video scrubbing, desktop and tablet screens provide the most comfortable experience.