About

MicroDVD (.sub) subtitles encode timing as frame numbers, not timestamps. Converting to SubRip (.srt) requires dividing each frame index by the video's framerate to produce HH:MM:SS,mmm timecodes. An incorrect FPS value shifts every cue in the file. At 23.976 fps, a single-frame error equals 41.7 ms. At 29.97 fps it drops to 33.4 ms. Accumulated drift over a two-hour film can exceed 2 seconds, making dialogue visibly out of sync. This converter auto-detects the FPS header that most MicroDVD files embed in their first line ({1}{1}23.976), and falls back to a user-specified rate when the header is absent.

The tool handles pipe-delimited line breaks (| → newline), strips byte-order marks, and normalises mixed line endings. All processing runs in your browser. No file is uploaded to any server. Note: this tool assumes constant framerate video. Variable framerate sources (screen recordings, some webcam footage) will produce drift that no frame-based converter can fully correct.

Formulas

Each MicroDVD line stores a start frame and end frame. The conversion to SRT timecodes uses the video framerate as the divisor.

t = fFPS

Where t is time in seconds and f is the frame number. The millisecond component is extracted as:

ms = floor(t × 1000) mod 1000

Hours, minutes, and seconds decompose from total seconds:

h = floor(t ÷ 3600)

m = floor((t − h × 3600) ÷ 60)

s = floor(t − h × 3600 − m × 60)

The final SRT timecode format is HH:MM:SS,mmm. The MicroDVD pipe character | is replaced with a line break in the SRT text block. If the first line matches the pattern {1}{1} followed by a decimal number, it is treated as the FPS declaration and excluded from subtitle output.

Reference Data

Standard	FPS Value	Frame Duration	Usage
NTSC Film	23.976 fps	41.708 ms	Blu-ray film, streaming (US/JP)
Cinema	24.000 fps	41.667 ms	Theatrical projection (DCI)
PAL / SECAM	25.000 fps	40.000 ms	European broadcast, DVD Region 2
NTSC Video	29.970 fps	33.367 ms	US broadcast (drop-frame TC)
NTSC Non-Drop	30.000 fps	33.333 ms	Non-drop-frame NTSC, some web
PAL High	50.000 fps	20.000 ms	PAL interlaced fields, sports
NTSC High	59.940 fps	16.683 ms	NTSC interlaced fields, gaming capture
Web Standard	60.000 fps	16.667 ms	YouTube, Twitch, gaming
MicroDVD Header	First line {1}{1}fps_value - parsed automatically if present
SRT Index	Sequential integer starting at 1, incremented per cue
SRT Timecode	HH:MM:SS,mmm → comma separator (not dot)
SRT Separator	--> with spaces on both sides
MicroDVD Pipe	\| character maps to a newline in SRT text block
BOM	UTF-8 BOM (0xEF 0xBB 0xBF) stripped during parsing
Max Drift (23.976)	±41.7 ms per frame error
Max Drift (29.97)	±33.4 ms per frame error
Encoding	UTF-8 recommended. ANSI/Latin-1 files may lose diacritics.

Frequently Asked Questions

MicroDVD files commonly embed the framerate in the first line using the pattern {1}{1}23.976 (or similar float). The converter checks if the first line's text portion is a valid number between 1 and 120. If it matches, that value is used as FPS and the line is excluded from the SRT output. If not detected, the user-specified FPS input is used instead.

Every subtitle cue will be offset. The error per frame equals 1/FPS seconds. For a file authored at 25 fps but converted at 23.976 fps, a subtitle at frame 25000 would appear at 00:17:22,684 instead of the correct 00:16:40,000 - a drift of over 42 seconds. Always verify your video's actual framerate using a tool like MediaInfo before converting.

MicroDVD supports inline formatting tags like {y:i} for italic or {c:$0000FF} for color. The converter preserves raw text as-is. SRT supports basic HTML-like tags (<i>, <b>, <u>), but MicroDVD tags use a different syntax. Proprietary MicroDVD style codes will appear as plain text in the SRT output. Manual find-and-replace or a dedicated subtitle editor is recommended for style conversion.

The SubRip (SRT) specification mandates a comma as the millisecond separator: HH:MM:SS,mmm. Many players tolerate a dot, but strict parsers (broadcast systems, professional NLEs) will reject files with dot separators. This converter always outputs the standard comma format.

The converter processes files up to 50 MB entirely in your browser. For files exceeding 500 KB, parsing is offloaded to a Web Worker to prevent UI freezing. A typical 2-hour film subtitle file is usually under 100 KB, so the limit accommodates even concatenated multi-episode files.

MicroDVD uses the pipe character | to denote line breaks within a single subtitle entry. For example, {100}{200}Line one.|Line two. becomes two separate text lines in the SRT output block. The converter splits on every | occurrence and trims whitespace from each resulting line.

Yes, provided the source file is encoded in UTF-8. The FileReader API reads the file as UTF-8 text by default. If your .sub file uses ANSI, Windows-1252, or another legacy encoding, characters outside ASCII may be garbled. Convert the file to UTF-8 in a text editor before using this tool.