SubtitleEdit/subtitleedit · error · InvalidOperationException

BinaryOCR database is empty: {dbPath}

Error message

BinaryOCR database is empty: {dbPath}

What it means

InvalidOperationException from the BinaryOcrOcrEngine constructor: the .db file exists and loaded, but AllCompareImages is empty — i.e. the database has no trained glyph entries, so recognition would always return nothing. This is distinct from 'file not found' (the file is present but useless).

Source

Thrown at src/seconv/Core/BinaryOcrOcrEngine.cs:32

    public string Name => "binaryocr";

    private readonly BinaryOcrDb _db;
    private readonly BinaryOcrMatcher _matcher;
    private const int PixelsAreSpaceDefault = 12;
    private const double MaxErrorPercent = 0.5;

    public BinaryOcrOcrEngine(string dbPath)
    {
        if (!File.Exists(dbPath))
        {
            throw new FileNotFoundException(
                $"BinaryOCR database not found: {dbPath}. Use --ocr-db to point to a .db file " +
                "(typically %AppData%\\Subtitle Edit\\OCR\\Latin.db or similar).", dbPath);
        }
        _db = new BinaryOcrDb(dbPath, loadCompareImages: true);
        if (_db.AllCompareImages.Count == 0)
        {
            throw new InvalidOperationException($"BinaryOCR database is empty: {dbPath}");
        }
        _matcher = new BinaryOcrMatcher
        {
            IsLatinDb = Path.GetFileNameWithoutExtension(dbPath).Contains("Latin", StringComparison.OrdinalIgnoreCase),
        };
    }

    public string Recognize(SKBitmap bitmap)
    {
        if (bitmap is null || bitmap.Width == 0 || bitmap.Height == 0)
        {
            return string.Empty;
        }

        var parent = new NikseBitmap2(bitmap);
        parent.MakeTwoColor(200);
        parent.CropTop(0, new SKColor(0, 0, 0, 0));
        var letters = NikseBitmapImageSplitter2.SplitBitmapToLettersNew(

View on GitHub (pinned to 17a9f07487)

Solutions

1. Regenerate the .db in the SE GUI by training on actual subtitle images.
2. Open the .db in the SE Binary/OCR editor and confirm it has compare images; if empty, retrain.
3. Use a different, known-good .db (e.g. a Latin.db from another install).

Example fix

// before
if (_db.AllCompareImages.Count == 0)
    throw new InvalidOperationException($"BinaryOCR database is empty: {dbPath}");

// after
if (_db.AllCompareImages.Count == 0)
    throw new InvalidOperationException($"BinaryOCR database '{dbPath}' loaded but has 0 compare images ({_db.AllCompareImages.Count} entries). Retrain it in the SE GUI.");

using var probe = new BinaryOcrDb(dbPath, loadCompareImages: true);
if (probe.AllCompareImages.Count == 0)
    throw new InvalidOperationException($"BinaryOCR db '{dbPath}' is empty; retrain in the SE GUI.");

static bool OcrDbHasEntries(string path) { using var d = new BinaryOcrDb(path, loadCompareImages: true); return d.AllCompareImages.Count > 0; }

null

When it happens

Trigger: Loading a BinaryOCR .db that was created empty, corrupted, or partially written; loadCompareImages:true returned zero compare images.

Common situations: An aborted/cancelled SE GUI training session left a zero-row .db; copied a placeholder .db; format mismatch where the loader skipped all entries silently.

Related errors

• BinaryOCR database not found: {dbPath}. Use --ocr-db to poin
• nOCR database not found: {nOcrDbPath}. Use --ocr-db to point
• nOCR database is empty: {nOcrDbPath}
• OCR engine '{options.OcrEngine}' is not supported. Use one o
• {engineName} engine requires --ocr-db=<path-to-Latin{require

AI-assisted analysis of SubtitleEdit/subtitleedit@17a9f07487 (2026-08-13). Data as JSON: /api/errors/b4dbd79e90f31ba3. Report an issue: GitHub.