SubtitleEdit/subtitleedit · error · FormatException

Offset is empty.

Error message

Offset is empty.

What it means

Thrown by OffsetParser.Parse when the `--offset` value is null, empty, or whitespace. OffsetParser converts the legacy Subtitle Edit offset syntax (ms, ss:ms, mm:ss:ms, hh:mm:ss:ms) into a TimeSpan; an empty string has no parseable tokens, so it fails fast with FormatException.

Source

Thrown at src/seconv/Core/OffsetParser.cs:17

using System.Globalization;

namespace SeConv.Core;

/// <summary>
/// Parses offset strings in the legacy Subtitle Edit CLI format. Accepts
/// a plain integer (milliseconds) or colon/comma/period separated integer
/// tokens treated as (hh, mm, ss, ms) — 4 tokens = hh:mm:ss:ms,
/// 3 = mm:ss:ms, 2 = ss:ms, 1 = ms. Optional leading +/- repeated.
/// </summary>
internal static class OffsetParser
{
    public static TimeSpan Parse(string input)
    {
        if (string.IsNullOrWhiteSpace(input))
        {
            throw new FormatException("Offset is empty.");
        }

        var s = input.Trim();
        var negate = false;
        while (s.Length > 0 && (s[0] == '-' || s[0] == '+'))
        {
            if (s[0] == '-')
            {
                negate = !negate;
            }
            s = s[1..];
        }

        if (s.Length == 0)
        {
            throw Bad(input);
        }

View on GitHub (pinned to 17a9f07487)

Solutions

1. Provide a concrete offset value, e.g. `--offset=1000` (1 second) or `--offset=00:00:01,500`.
2. If no offset is wanted, omit the `--offset` flag entirely rather than passing an empty value.
3. Guard wrapper scripts: only emit `--offset=` when the variable is non-empty.

Example fix

# before
seconv in.srt out.srt --offset=
# after
seconv in.srt out.srt --offset=1000

if (string.IsNullOrWhiteSpace(rawOffset))
    throw new ArgumentException("--offset requires a value (ms or hh:mm:ss:ms)");
var ts = OffsetParser.Parse(rawOffset);

static bool IsOffsetParsable(string? s)
{
    if (string.IsNullOrWhiteSpace(s)) return false;
    try { OffsetParser.Parse(s); return true; } catch { return false; }
}

try { var offset = OffsetParser.Parse(input); }
catch (FormatException ex) when (ex.Message == "Offset is empty.")
{
    // treat as no offset, or report and abort
}

When it happens

Trigger: Calling `OffsetParser.Parse(input)` with an empty/whitespace string, typically because `--offset=` was passed with no value or the option was bound to an unset environment variable.

Common situations: Shell expansion that blanks the value (`--offset=$OFFSET` with OFFSET unset); a wrapper script passing an empty default; quoting mistake that strips the argument.

Related errors

• PAC code page is empty.
• Resolution is empty.
• {StaticName} returned an unexpected response: {responseStrin
• Translate engine '{options.TranslateEngine}' is not supporte
• Translate model '{name}' not found in {LlamaCppServerManager

AI-assisted analysis of SubtitleEdit/subtitleedit@17a9f07487 (2026-08-13). Data as JSON: /api/errors/5cde9f39668b7372. Report an issue: GitHub.