macSubtitleOCR / PGS to SRT

Blu-ray bitmap subtitle guide

How to convert PGS or SUP subtitles to SRT on Mac

PGS subtitles are images, so changing them into editable text requires OCR. macSubtitleOCR reads PGS tracks directly from MKV, MKS, and SUP files, recognizes them locally with Apple Vision, and keeps every source bitmap beside the resulting line.

Download macSubtitleOCRStart the guide

Free and open source · macOS 15+ · No MKVToolNix required

What you need

You need a Mac running macOS 15 or newer, the free macSubtitleOCR app, and one of these PGS subtitle sources:

SourceWhat the app reads
.mkv or .mksEvery embedded PGS subtitle track, including language, title, default, and forced flags.
.supA standalone Blu-ray PGS stream.
.m2tsNot supported directly. Remux to MKV or extract the PGS stream as SUP first.

You do not need to install Homebrew, MKVToolNix, or Tesseract. The signed app contains its own Matroska reader and PGS decoder and uses the Vision framework already in macOS.

Convert PGS to SRT step by step

  1. Open the source. Drag an MKV, MKS, or SUP file onto macSubtitleOCR, or choose File → Open. You can also drop a folder to queue several files.
  2. Select the PGS track. Expand the source to see track language, name, flags, and cue count. Correct the language if the file is missing or mislabeling it, then tick the tracks you need.
  3. Choose the output location. The default saves SRT files beside the source. Use the toolbar to choose another folder or ask each time.
  4. Choose Make Subtitles. The app decodes each PGS display set and sends its rendered text image to Apple Vision. Progress shows actual cue counts.
  5. Review the result. Check low-confidence cues first, compare the text with the original bitmap, and edit mistakes inline. The SRT is updated as you type.

What file do you get?

PGS color, position, and graphics do not exist in SubRip. The output preserves cue timing and recognized text in a plain .srt file. Names include the detected language and, when useful, the source track name:

MyFilm.mkv
MyFilm.eng.srt
MyFilm.eng.english-sdh.srt

You can edit the SRT in a text editor or subtitle editor, mux it into an MP4 as a soft subtitle, or keep it beside the video for a player to discover.

How accurate is PGS OCR?

Accuracy depends on the disc’s typeface, resolution, outline, language, and image quality. Small italics, stylized dialogue, and letter pairs such as lowercase L and uppercase I deserve attention. That is why the app does not stop at OCR: it shows the exact PGS bitmap next to every recognized cue and flags lower-confidence results.

If a dark-on-light subtitle is recognized poorly, enable Invert images before recognition in the inspector and run the track again. Add recurring names or unusual words to Custom words.

What if the subtitles are in an M2TS file?

macSubtitleOCR does not read Blu-ray transport streams directly. Remux the disc or M2TS file to MKV with a tool such as MakeMKV, keeping the original PGS tracks. Then open that MKV. Remuxing does not need to re-encode the video.

Does the video or subtitle leave the Mac?

No. PGS decoding and Vision recognition happen locally. Optional Apple Intelligence clean-up and Translation features are local too. The app can make one optional daily request to GitHub to check whether a newer release exists; disable that in Settings if you prefer.

Ready to convert?

Download the signed, notarized universal app, then open the PGS source you already have.

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