SubtitleEdit/subtitleedit · error · InvalidOperationException

No subtitle essences found in MXF: {filePath}

Error message

No subtitle essences found in MXF: {filePath}

What it means

Thrown when an MXF is valid but contains neither text subtitle essences nor image essences — both GetSubtitles() and GetImages() return empty lists. The file is structurally an MXF but carries no subtitle content at all, so there is nothing to extract.

Source

Thrown at src/seconv/Core/ContainerSubtitleLoader.cs:182

        {
            // Not a real MXF (no Header Partition Pack signature). Fall through to the
            // text loader — the file might just have a misleading extension.
            return null;
        }

        var subtitleTexts = parser.GetSubtitles();
        var images = parser.GetImages();

        if (subtitleTexts.Count == 0)
        {
            if (images.Count > 0)
            {
                throw new InvalidOperationException(
                    $"MXF contains {images.Count} image essence(s) but no text subtitles. "
                    + "Image-based MXF subtitles (PNG essences) aren't supported yet — "
                    + "the parser doesn't reconstruct per-essence PTS, so the bitmaps have no timing.");
            }
            throw new InvalidOperationException($"No subtitle essences found in MXF: {filePath}");
        }

        if (images.Count > 0)
        {
            AnsiConsole.MarkupLine(
                $"[yellow]Note: MXF also contains {images.Count} image essence(s) — skipped (no timing context).[/]");
        }

        var tracks = new List<LoadedTrack>();
        var trackNumber = 1;
        foreach (var subtitleText in subtitleTexts)
        {
            // Honour --track-number against the 1-based essence index — mirrors how
            // LoadMatroska / LoadMp4 filter their multi-track inputs (line ~96).
            if (options.TrackNumbers.Count > 0 && !options.TrackNumbers.Contains(trackNumber))
            {
                trackNumber++;
                continue;

View on GitHub (pinned to 17a9f07487)

Solutions

1. Confirm the MXF actually contains subtitle essences with ffprobe / an MXF inspector.
2. If subtitles exist in another track/container, target that source instead.
3. Re-wrap the original to include the subtitle essence.

// Probe for subtitle essences with ffprobe before invoking the loader.
// (No direct public API; treat ffprobe output as the validation step.)
var hasSubs = ProbeHasSubtitleEssence(mxfPath);
if (!hasSubs) return Error($"No subtitle essences in {mxfPath}");

try { tracks = ContainerSubtitleLoader.TryLoadTracks(mxfPath, options); }
catch (InvalidOperationException ex) when (ex.Message.Contains("No subtitle essences"))
{ Console.Error.WriteLine(ex.Message); return; }

When it happens

Trigger: Loading a valid MXF (parser.IsValid true) where the subtitleTexts list (line 170) is empty and images.Count is also 0 — e.g. a video/audio-only MXF, or one whose subtitle essence was stripped.

Common situations: Pointing seconv at a video-only or audio-only MXF master; an MXF whose subtitle track was removed during re-wrapping; an MXF with an unrecognised/non-subtitle essence that the parser ignores.

Related errors

• Failed to parse MXF file '{filePath}': {ex.Message}
• MXF contained {subtitleTexts.Count} candidate subtitle essen
• MXF contains {images.Count} image essence(s) but no text sub
• MXF contained {subtitleTexts.Count} essence(s) but none matc
• No subtitle tracks in MP4 file: {filePath}

AI-assisted analysis of SubtitleEdit/subtitleedit@17a9f07487 (2026-08-13). Data as JSON: /api/errors/fa816c30bc553a60. Report an issue: GitHub.