SubtitleEdit/subtitleedit · error · InvalidOperationException

No PGS subtitles in MKV track #{track.TrackNumber}.

Error message

No PGS subtitles in MKV track #{track.TrackNumber}.

What it means

Thrown by ImageOcrLoader.LoadMatroskaPgs when BluRaySupParser.ParseBluRaySupFromMatroska(track, matroska) returns an empty PCS list for the given MKV PGS track (codec S_HDMV/PGS). The track was selected as a PGS subtitle track but its embedded PGS data decoded to zero presentation composition segments, so there is nothing to OCR.

Source

Thrown at src/seconv/Core/ImageOcrLoader.cs:54

            return PcsListToSubtitle(pcsList, null);
        }

        using var ocr = OcrEngineFactory.Create(options);
        var isolationNote = options.PgsIsolateColors ? string.Empty : " (colour isolation off)";
        AnsiConsole.MarkupLine($"[dim]Running {ocr.Name} OCR on {pcsList.Count} Blu-Ray sup image(s){isolationNote}...[/]");
        return PcsListToSubtitle(pcsList, ocr, options.PgsIsolateColors);
    }

    /// <summary>
    /// MKV PGS track (S_HDMV/PGS) → text via the configured OCR engine, or time codes only
    /// when <see cref="ConversionOptions.TimeCodesOnly"/> is set.
    /// </summary>
    public static Subtitle LoadMatroskaPgs(MatroskaFile matroska, MatroskaTrackInfo track, ConversionOptions options)
    {
        var pcsList = BluRaySupParser.ParseBluRaySupFromMatroska(track, matroska);
        if (pcsList.Count == 0)
        {
            throw new InvalidOperationException($"No PGS subtitles in MKV track #{track.TrackNumber}.");
        }

        if (options.TimeCodesOnly)
        {
            AnsiConsole.MarkupLine($"[dim]Extracting time codes from {pcsList.Count} MKV PGS image(s) (track #{track.TrackNumber}, no OCR)...[/]");
            return PcsListToSubtitle(pcsList, null);
        }

        using var ocr = OcrEngineFactory.Create(options);
        var isolationNote = options.PgsIsolateColors ? string.Empty : " (colour isolation off)";
        AnsiConsole.MarkupLine($"[dim]Running {ocr.Name} OCR on {pcsList.Count} MKV PGS image(s) (track #{track.TrackNumber}){isolationNote}...[/]");
        return PcsListToSubtitle(pcsList, ocr, options.PgsIsolateColors);
    }

    /// <summary>
    /// Transport stream DVB-sub → text via the configured OCR engine, or time codes only
    /// when <see cref="ConversionOptions.TimeCodesOnly"/> is set. Returns one Subtitle per
    /// packet ID that has subtitles. Teletext PIDs are not handled here (they're already

View on GitHub (pinned to 17a9f07487)

Solutions

1. Extract the PGS track to a standalone .sup (mkvextract / ffmpeg) and validate it with BDSup2Sub.
2. Re-mux the MKV from the original Blu-ray source including the intact PGS track.
3. If the track is empty/corrupt, select a different PGS track or re-extract subtitles from the source.

// Extract the PGS track to .sup first and validate, then OCR the standalone file.
// (No public pre-check for embedded PGS; rely on the loader guard.)

try { sub = ImageOcrLoader.LoadMatroskaPgs(matroska, track, options); }
catch (InvalidOperationException ex) when (ex.Message.Contains("No PGS subtitles in MKV track"))
{ AnsiConsole.MarkupLine($"[yellow]Skipping PGS track #{track.TrackNumber}: {ex.Message.EscapeMarkup()}[/]"); continue; }

When it happens

Trigger: Calling LoadMatroskaPgs(matroska, track, options) on an MKV PGS track whose payload contains no usable PCS entries (ImageOcrLoader.cs:55). Occurs with a corrupt/truncated PGS track or a track flagged S_HDMV/PGS that is actually empty.

Common situations: A PGS track truncated during muxing; an MKV whose PGS packets were corrupted by a faulty remux; a placeholder PGS track; a track whose PGS data is compressed/encoded in a way the parser rejects.

Related errors

• No Blu-Ray sup subtitles found in: {filePath}
• No VobSub subtitles in MKV track #{track.TrackNumber}.
• No subtitle tracks in Matroska file: {filePath}
• No subtitles recognised in Blu-Ray sup file: {filePath}
• Unable to access bitmap pixel data.

AI-assisted analysis of SubtitleEdit/subtitleedit@17a9f07487 (2026-08-13). Data as JSON: /api/errors/646a20ea2f117375. Report an issue: GitHub.