SubtitleEdit/subtitleedit · error · FormatException

Invalid ASSA time code: {time}

Error message

Invalid ASSA time code: {time}

What it means

Thrown by AdvancedSubStationAlpha.GetTimeCodeFromString when a Dialogue line's start/end time field does not contain the expected h:mm:ss.cc separators. The parser uses IndexOfAny(':', '.') three times to slice the span; if any of the three separators is missing (i1/i2/i3 < 0) the time is unparseable and a FormatException is raised. This fires twice per Dialogue line during file load.

Source

Thrown at src/libse/SubtitleFormats/AdvancedSubStationAlpha.cs:1980

            subtitle.Renumber();
            Errors = errors.ToString();
        }

        private static TimeCode GetTimeCodeFromString(string time)
        {
            // h:mm:ss.cc - parsed with span slices; this runs twice per Dialogue line when
            // loading a file, and the previous Split(':', '.') allocated a string[] plus one
            // substring per part for every call.
            var span = time.AsSpan();
            var i1 = span.IndexOfAny(':', '.');
            var afterHours = i1 < 0 ? default : span.Slice(i1 + 1);
            var i2 = afterHours.IndexOfAny(':', '.');
            var afterMinutes = i2 < 0 ? default : afterHours.Slice(i2 + 1);
            var i3 = afterMinutes.IndexOfAny(':', '.');
            if (i1 < 0 || i2 < 0 || i3 < 0)
            {
                throw new FormatException($"Invalid ASSA time code: {time}");
            }

            var afterSeconds = afterMinutes.Slice(i3 + 1);
            var i4 = afterSeconds.IndexOfAny(':', '.');
            var lastPart = (i4 < 0 ? afterSeconds : afterSeconds.Slice(0, i4)).Trim();

            var ms = 0;
            if (lastPart.Length == 2) // correct ASSA time code
            {
                ms = int.Parse(lastPart) * 10;
            }
            else if (lastPart.Length == 3)
            {
                ms = int.Parse(lastPart); // 3 digits, e.g. 123 = 123 ms
            }
            else if (lastPart.Length > 3)
            {
                ms = int.Parse(lastPart.Slice(0, 2)) * 10;

View on GitHub (pinned to 17a9f07487)

Solutions

1. Open the .ass file in a text editor and verify every Dialogue line's start/end times match h:mm:ss.cc (e.g. 0:00:01.23).
2. If the file is a different format, force the correct format in SubtitleEdit instead of relying on auto-detection.
3. Fix the offending line(s) manually or re-export from the original source.
4. If loading programmatically, pre-validate times with a regex before calling LoadSubtitle.

Example fix

// before
Dialogue: 0,1:23,2:00,Default,,0,0,0,,Hi
// after
Dialogue: 0,0:01:23.00,0:02:00.00,Default,,0,0,0,,Hi

// Validate an ASSA time string before passing it to a loader/serializer
static bool IsValidAssaTime(string time)
{
    if (string.IsNullOrWhiteSpace(time)) return false;
    // Expect h:mm:ss.cc — at least three ':' or '.' separators
    var sepCount = 0;
    foreach (var c in time)
    {
        if (c == ':' || c == '.') sepCount++;
    }
    return sepCount >= 3;
}

// usage before load
if (lines.Any(l => l.StartsWith("Dialogue:", StringComparison.Ordinal)
    && !IsValidAssaTime(l.Split(',')[1])))
{
    // warn user / sanitize
}

// Wrap LoadSubtitle to report the offending line
try
{
    new AdvancedSubStationAlpha().LoadSubtitle(sub, lines, fileName);
}
catch (FormatException ex) when (ex.Message.StartsWith("Invalid ASSA time code"))
{
    // log ex.Message, prompt user to fix the time field, do not swallow silently
    logger.Error(ex, "ASSA time code parse failed");
    throw;
}

When it happens

Trigger: Loading an .ass/.ssa file whose Dialogue timing fields are malformed — e.g. '1:23' (missing seconds or centiseconds), '123' (no separators at all), empty string, or a value using a comma instead of a dot/colon. Also triggered if a non-ASSA file is misdetected as ASSA.

Common situations: Hand-edited subtitle files with typos in time fields, files generated by a buggy exporter that drops the centisecond part, locale-specific files using comma decimal separators, or files with trailing/leading whitespace in the time field.

Related errors

• Unknown time format '{timeFormat}'
• Unknown type of event #{i + 1}: '{type}'
• Element 'events' not found.
• Parse error in event #{i + 1} style: {ex.Message}
• Parse error in event #{i + 1}: {ex.Message}

AI-assisted analysis of SubtitleEdit/subtitleedit@17a9f07487 (2026-08-13). Data as JSON: /api/errors/75acfdca2fbef2f0. Report an issue: GitHub.