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Document format

SUB converter

A .sub file in the MicroDVD convention is a frame-based subtitle list: every line reads {startFrame}{endFrame}text, with a pipe character separating the lines inside one cue. Because the timing is expressed in frames rather than milliseconds, a MicroDVD file only means anything alongside the frame rate of the video it was timed to.

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Drop SUB files here

Batch files can each use a different output. Nothing uploads for local conversions.

Working inputs include camera RAW, browser-local audio/video, PDF, CBZ/CBR comics, office documents, ebooks, markup, 3D models, structured text, images, and archives.

Where SUB comes from

The format takes its name from the MicroDVD player of the late 1990s, when subtitles were routinely timed against a specific DivX rip rather than a timeline. The convention of putting the frame rate in a leading {1}{1} line grew up because so many files were shared without it and played back at the wrong speed.

How SUB works

  • Each cue is one line: {startFrame}{endFrame} followed by the text, with | separating multiple display lines.
  • A leading {1}{1}<fps> line declares the frame rate; without one, players assume a default, most commonly 23.976.
  • Inline control tags in braces — {y:i}, {c:$0000ff}, {f:Arial} — set italics, colour, and font for a cue or the whole file.
  • Frame granularity means the achievable timing precision is one frame, about 40 ms at 25 fps.
  • The extension is shared with VobSub, whose .sub is a binary MPEG stream paired with an .idx index and is an entirely different format.

When to use SUB

  • Playing back subtitles that were timed against a specific video rip
  • Editing cue timing in frames rather than clock time
  • Recovering dialogue from an old subtitle archive
  • Converting frame-based subtitles into millisecond caption formats for the web

Strengths and limitations

Strengths

  • Extremely compact — one line per cue
  • Frame timing matches the source video exactly when the frame rate is known
  • Trivially editable in any text editor

Limitations

  • Meaningless without the correct frame rate; the wrong value drifts the whole file
  • The .sub extension collides with VobSub, so the extension alone does not identify the format
  • No positioning or region support, and the styling tags are non-standard

Compatibility

VLC, MPC-HC, and most desktop players read MicroDVD .sub, and Subtitle Edit converts it. Browsers do not. Novus Convert reads the frame rate from the file's own {1}{1} declaration and falls back to 23.976 when none is present; a binary VobSub .sub is rejected with an explanation rather than being parsed as text. MicroDVD output is written at 25 fps with that rate declared in the first line, so a converted file round-trips to the frame.

There is no metadata section; the only header-like content is the frame-rate declaration, which is read on input and written on output.

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