nilaoda/N_m3u8DL-RE · error · ArgumentException

Invalid Speed Limit

Error message

Invalid Speed Limit: {input}

What it means

CommandInvoker.ParseSpeedLimit validates the --speed-limit (or equivalent) CLI option value against SpeedStrRegex, which expects a number followed by a unit (K or M, e.g. '10M' or '512k'). If the input does not match the expected '<number>[K|M]' format, it throws ArgumentException "Invalid Speed Limit: {input}" before the download starts.

Solutions

1. Use the accepted format: a plain number optionally followed by K or M, e.g. '10M' or '512K' (bytes/s).
2. Remove unit suffixes like 'bps', '/s', or spaces: '10Mbps' -> '10M'.
3. Use only K/M units; convert G to M (e.g. '1G' -> '1024M').
4. Use '.' as the decimal separator, not ','.

Example fix

// before
--speed-limit "10Mbps"
// after
--speed-limit "10M"

// validate the speed limit against the same pattern the CLI uses
static bool IsValidSpeedLimit(string input) =>
    System.Text.RegularExpressions.Regex.IsMatch(
        (input ?? "").ToUpperInvariant(), @"^([0-9]+(?:\.[0-9]+)?)([KM])$");
if (!IsValidSpeedLimit(userInput)) throw new ArgumentException($"Invalid Speed Limit: {userInput}");

try { cli.Parse(args); }
catch (ArgumentException ex) when (ex.Message.StartsWith("Invalid Speed Limit")) {
    Console.Error.WriteLine($"{ex.Message} -- use format like '10M' or '512K' (bytes/s)");
    Environment.Exit(1);
}

When it happens

Trigger: The user passes a speed limit value that does not match the number+K/M pattern, e.g. '10Mbps', '10 MB/s', '0.5G', 'abc', or a bare number with an unsupported unit suffix.

Common situations: Typos like '10M/s' or '10mbps'; users assuming bits vs bytes or G/T units are accepted; quoting/whitespace issues in shell scripts; localization decimal commas ('1,5M').

Understand the failure class

Background: "Unknown argument", "Invalid value", and "must be one of": invalid CLI argument errors explained — this error's family across 35 libraries.

Related errors

• MuxAfterDone disabled, MuxImports not allowed!
• Mp4 box names must be 4 characters long
• Bad format!
• must be valid 16-byte HEX or Base64. Input string
• Input must be KEY or KID:KEY format.

AI-assisted analysis of nilaoda/N_m3u8DL-RE@e113dee70c (2026-09-13). Data as JSON: /api/errors/31f6fec59e6b84b1. Report an issue: GitHub.

Appendix: source

Thrown at src/N_m3u8DL-RE/CommandLine/CommandInvoker.cs:130

    private static readonly Option<StreamFilter?> AudioFilter = new("-sa", "--select-audio") { HelpName = "OPTIONS", Description = ResString.cmd_selectAudio, CustomParser = ParseStreamFilter };
    private static readonly Option<StreamFilter?> SubtitleFilter = new("-ss", "--select-subtitle") { HelpName = "OPTIONS", Description = ResString.cmd_selectSubtitle, CustomParser = ParseStreamFilter };

    private static readonly Option<StreamFilter?> DropVideoFilter = new("-dv", "--drop-video") { HelpName = "OPTIONS", Description = ResString.cmd_dropVideo, CustomParser = ParseStreamFilter };
    private static readonly Option<StreamFilter?> DropAudioFilter = new("-da", "--drop-audio") { HelpName = "OPTIONS", Description = ResString.cmd_dropAudio, CustomParser = ParseStreamFilter };
    private static readonly Option<StreamFilter?> DropSubtitleFilter = new("-ds", "--drop-subtitle") { HelpName = "OPTIONS", Description = ResString.cmd_dropSubtitle, CustomParser = ParseStreamFilter };

    /// <summary>
    /// 解析下载速度限制
    /// </summary>
    /// <param name="result"></param>
    /// <returns></returns>
    private static long? ParseSpeedLimit(ArgumentResult result)
    {
        var input = result.Tokens[0].Value.ToUpper();
        try
        {
            var reg = SpeedStrRegex();
            if (!reg.IsMatch(input)) throw new ArgumentException($"Invalid Speed Limit: {input}");

            var number = double.Parse(reg.Match(input).Groups[1].Value);
            if (reg.Match(input).Groups[2].Value == "M")
                return (long)(number * 1024 * 1024);
            return (long)(number * 1024);
        }
        catch (Exception)
        {
            result.AddError("error in parse SpeedLimit: " + input);
            return null;
        }
    }

    /// <summary>
    /// 解析用户定义的下载范围
    /// </summary>
    /// <param name="result"></param>
    /// <returns></returns>

View on GitHub (pinned to e113dee70c)