Allow explicit NTSC for VOB extraction

src/seconv/Commands/ConvertCommand.cs

@@ -17,6 +17,17 @@ internal sealed class ConvertCommand : AsyncCommand<ConvertCommand.Settings>
     /// </summary>
     public static string[] RawArgs { get; set; } = [];
 
+    internal static bool ResolveVobIsPal(bool vobPal, bool vobNtsc)
+    {
+        if (vobPal && vobNtsc)
+        {
+            throw new ArgumentException("--vob-pal and --vob-ntsc are mutually exclusive.");
+        }
+
+        // Preserve the existing CLI behaviour unless NTSC is explicitly selected.
+        return !vobNtsc;
+    }
+
     public sealed class Settings : CommandSettings
     {
         [CommandArgument(0, "<pattern>")]
@@ -71,6 +82,14 @@ public sealed class Settings : CommandSettings
         [Description("Frame rate")]
         public double? Fps { get; init; }
 
+        [CommandOption("--vob-pal")]
+        [Description("VOB input: treat DVD video as PAL (720x576; default)")]
+        public bool VobPal { get; init; }
+
+        [CommandOption("--vob-ntsc")]
+        [Description("VOB input: treat DVD video as NTSC (720x480)")]
+        public bool VobNtsc { get; init; }
+
         [CommandOption("--input-folder|--inputfolder")]
         [Description("Input folder name")]
         public string? InputFolder { get; init; }
@@ -687,6 +706,16 @@ protected override async Task<int> ExecuteAsync(CommandContext context, Settings
                 return Fail(settings, $"--change-speed must be greater than 0 (got {settings.ChangeSpeed.Value}).");
             }
 
+            bool vobIsPal;
+            try
+            {
+                vobIsPal = ResolveVobIsPal(settings.VobPal, settings.VobNtsc);
+            }
+            catch (ArgumentException ex)
+            {
+                return Fail(settings, ex.Message);
+            }
+
             // Parse offset if supplied
             TimeSpan? offset = null;
             if (!string.IsNullOrWhiteSpace(settings.Offset))
@@ -742,6 +771,7 @@ protected override async Task<int> ExecuteAsync(CommandContext context, Settings
                 InputEncodingFallback = settings.InputEncodingFallback,
                 Fps = settings.Fps,
                 TargetFps = settings.TargetFps,
+                VobIsPal = vobIsPal,
                 Overwrite = settings.Overwrite,
                 KeepTimestamp = settings.KeepTimestamp,
                 Operations = operations,

src/seconv/Core/SubtitleConverter.cs

@@ -262,10 +262,9 @@ private async Task<ConversionResult> ConvertVobBatchAsync(List<string> vobFiles,
 
         try
         {
-            // IsPal — there's no single reliable auto-detect from VOB alone (would need
-            // IFO parsing). Default to PAL to match the GUI's batch converter. Future
-            // work: add --vob-pal/--vob-ntsc and/or read VIDEO_TS.IFO.
-            var outputs = VobSubExtractor.Extract(vobFiles, outputBase, isPal: true, overwrite: options.Overwrite);
+            // There is no reliable PAL/NTSC auto-detect from VOB alone without IFO parsing.
+            // Preserve PAL as the default, while allowing the CLI to select NTSC explicitly.
+            var outputs = VobSubExtractor.Extract(vobFiles, outputBase, options.VobIsPal, overwrite: options.Overwrite);
             result.SuccessfulFiles = vobFiles.Count;
             // Report the first stream's output path against each input VOB. With multiple
             // streams there's no clean 1:1 mapping back to inputs, but the OutputFile slot
@@ -1115,6 +1114,10 @@ internal record class ConversionOptions
     public string? InputEncodingFallback { get; init; }
     public double? Fps { get; init; }
     public double? TargetFps { get; init; }
+
+    /// <summary>DVD VOB extraction video standard. PAL remains the default for backwards compatibility.</summary>
+    public bool VobIsPal { get; init; } = true;
+
     public bool Overwrite { get; init; }
 
     /// <summary>--keep-timestamp: copy the source file's creation/last-write time onto every output file.</summary>

src/seconv/Helpers/HelpDisplay.cs

@@ -47,6 +47,8 @@ private static void ShowHelp(IAnsiConsole console)
         ShowParameter(console, "--input-encoding-fallback:<name>", "Assumed input encoding when no BOM and not UTF-8 (skips ANSI guess)");
         ShowParameter(console, "--forced-only", "Process forced subtitles only");
         ShowParameter(console, "--fps:<frame rate>", "Frame rate for conversion");
+        ShowParameter(console, "--vob-pal", "VOB input: treat DVD video as PAL (720x576; default)");
+        ShowParameter(console, "--vob-ntsc", "VOB input: treat DVD video as NTSC (720x480)");
         ShowParameter(console, "--input-folder:<folder name>", "Input folder path");
         ShowParameter(console, "--offset:hh:mm:ss:ms", "Time offset");
         ShowParameter(console, "--output-filename:<file name>", "Output file name (for single file only)");

tests/seconv/Core/VobSubExtractorTest.cs

@@ -1,3 +1,4 @@
+using SeConv.Commands;
 using SeConv.Core;
 using Xunit;
 
@@ -31,6 +32,32 @@ public void Dispose()
         }
     }
 
+    [Theory]
+    [InlineData(false, false, true)]
+    [InlineData(true, false, true)]
+    [InlineData(false, true, false)]
+    public void ResolveVobIsPal_SelectsExpectedStandard(bool vobPal, bool vobNtsc, bool expectedIsPal)
+    {
+        Assert.Equal(expectedIsPal, ConvertCommand.ResolveVobIsPal(vobPal, vobNtsc));
+    }
+
+    [Fact]
+    public void ResolveVobIsPal_RejectsConflictingFlags()
+    {
+        var ex = Assert.Throws<ArgumentException>(() => ConvertCommand.ResolveVobIsPal(vobPal: true, vobNtsc: true));
+        Assert.Contains("mutually exclusive", ex.Message);
+    }
+
+    [Fact]
+    public void ConversionOptions_VobStandardDefaultsToPal_AndAllowsNtsc()
+    {
+        var defaultOptions = new ConversionOptions { Patterns = [], Format = "VobSub" };
+        var ntscOptions = new ConversionOptions { Patterns = [], Format = "VobSub", VobIsPal = false };
+
+        Assert.True(defaultOptions.VobIsPal);
+        Assert.False(ntscOptions.VobIsPal);
+    }
+
     [Fact]
     public async Task ConvertAsync_VobInput_NonVobSubTarget_ErrorsWithGuidance()
     {