diff --git a/FFMpegCore.Test/ArgumentBuilderTest.cs b/FFMpegCore.Test/ArgumentBuilderTest.cs
index 082d9bf..5da3e0b 100644
--- a/FFMpegCore.Test/ArgumentBuilderTest.cs
+++ b/FFMpegCore.Test/ArgumentBuilderTest.cs
@@ -234,7 +234,7 @@ public void Builder_BuildString_FrameOutputCount()
         [TestMethod]
         public void Builder_BuildString_VideoStreamNumber()
         {
-            var str = FFMpegArguments.FromFileInput("input.mp4").OutputToFile("output.mp4", false, opt => opt.SelectStream(1)).Arguments;
+            var str = FFMpegArguments.FromFileInput("input.mp4").OutputToFile("output.mp4", false, opt => opt.SelectStream(0,1)).Arguments;
             Assert.AreEqual("-i \"input.mp4\" -map 0:1 \"output.mp4\"", str);
         }
 
diff --git a/FFMpegCore/FFMpeg/Arguments/MapStreamArgument.cs b/FFMpegCore/FFMpeg/Arguments/MapStreamArgument.cs
index 01a537d..6ce1dbe 100644
--- a/FFMpegCore/FFMpeg/Arguments/MapStreamArgument.cs
+++ b/FFMpegCore/FFMpeg/Arguments/MapStreamArgument.cs
@@ -1,17 +1,19 @@
 namespace FFMpegCore.Arguments
 {
     /// <summary>
-    /// Represents choice of video stream, works with one input file
+    /// Represents choice of video stream
     /// </summary>
     public class MapStreamArgument : IArgument
     {
+        private readonly int _inputFileIndex;
         private readonly int _streamIndex;
 
-        public MapStreamArgument(int index)
+        public MapStreamArgument(int inputFileIndex, int streamIndex)
         {
-            _streamIndex = index;
+            _inputFileIndex = inputFileIndex;
+            _streamIndex = streamIndex;
         }
 
-        public string Text => $"-map 0:{_streamIndex}";
+        public string Text => $"-map {_inputFileIndex}:{_streamIndex}";
     }
 }
\ No newline at end of file
diff --git a/FFMpegCore/FFMpeg/FFMpeg.cs b/FFMpegCore/FFMpeg/FFMpeg.cs
index 14556b4..bffbd1a 100644
--- a/FFMpegCore/FFMpeg/FFMpeg.cs
+++ b/FFMpegCore/FFMpeg/FFMpeg.cs
@@ -20,16 +20,17 @@ public static class FFMpeg
         /// <param name="output">Output video file path</param>
         /// <param name="captureTime">Seek position where the thumbnail should be taken.</param>
         /// <param name="size">Thumbnail size. If width or height equal 0, the other will be computed automatically.</param>
+        /// <param name="inputFileIndex">Input file index</param>
         /// <param name="streamIndex">Selected video stream index.</param>
         /// <returns>Bitmap with the requested snapshot.</returns>
-        public static bool Snapshot(string input, string output, Size? size = null, TimeSpan? captureTime = null, int streamIndex = 0)
+        public static bool Snapshot(string input, string output, Size? size = null, TimeSpan? captureTime = null, int inputFileIndex = 0, int? streamIndex = null)
         {
             if (Path.GetExtension(output) != FileExtension.Png)
                 output = Path.GetFileNameWithoutExtension(output) + FileExtension.Png;
 
             var source = FFProbe.Analyse(input);
-            var (arguments, outputOptions) = BuildSnapshotArguments(input, source, size, captureTime, streamIndex);
-            
+            var (arguments, outputOptions) = BuildSnapshotArguments(input, source, size, captureTime, inputFileIndex, streamIndex);
+
             return arguments
                 .OutputToFile(output, true, outputOptions)
                 .ProcessSynchronously();
@@ -41,16 +42,17 @@ public static bool Snapshot(string input, string output, Size? size = null, Time
         /// <param name="output">Output video file path</param>
         /// <param name="captureTime">Seek position where the thumbnail should be taken.</param>
         /// <param name="size">Thumbnail size. If width or height equal 0, the other will be computed automatically.</param>
+        /// <param name="inputFileIndex">Input file index</param>
         /// <param name="streamIndex">Selected video stream index.</param>
         /// <returns>Bitmap with the requested snapshot.</returns>
-        public static async Task<bool> SnapshotAsync(string input, string output, Size? size = null, TimeSpan? captureTime = null, int streamIndex = 0)
+        public static async Task<bool> SnapshotAsync(string input, string output, Size? size = null, TimeSpan? captureTime = null, int inputFileIndex = 0, int? streamIndex = null)
         {
             if (Path.GetExtension(output) != FileExtension.Png)
                 output = Path.GetFileNameWithoutExtension(output) + FileExtension.Png;
 
             var source = await FFProbe.AnalyseAsync(input);
-            var (arguments, outputOptions) = BuildSnapshotArguments(input, source, size, captureTime, streamIndex);
-            
+            var (arguments, outputOptions) = BuildSnapshotArguments(input, source, size, captureTime, inputFileIndex, streamIndex);
+
             return await arguments
                 .OutputToFile(output, true, outputOptions)
                 .ProcessAsynchronously();
@@ -62,14 +64,15 @@ public static async Task<bool> SnapshotAsync(string input, string output, Size?
         /// <param name="input">Source video file.</param>
         /// <param name="captureTime">Seek position where the thumbnail should be taken.</param>
         /// <param name="size">Thumbnail size. If width or height equal 0, the other will be computed automatically.</param>
+        /// <param name="inputFileIndex">Input file index</param>
         /// <param name="streamIndex">Selected video stream index.</param>
         /// <returns>Bitmap with the requested snapshot.</returns>
-        public static Bitmap Snapshot(string input, Size? size = null, TimeSpan? captureTime = null, int streamIndex = 0)
+        public static Bitmap Snapshot(string input, Size? size = null, TimeSpan? captureTime = null, int inputFileIndex = 0, int? streamIndex = null)
         {
             var source = FFProbe.Analyse(input);
-            var (arguments, outputOptions) = BuildSnapshotArguments(input, source, size, captureTime, streamIndex);
+            var (arguments, outputOptions) = BuildSnapshotArguments(input, source, size, captureTime, inputFileIndex, streamIndex);
             using var ms = new MemoryStream();
-            
+
             arguments
                 .OutputToPipe(new StreamPipeSink(ms), options => outputOptions(options
                     .ForceFormat("rawvideo")))
@@ -85,14 +88,15 @@ public static Bitmap Snapshot(string input, Size? size = null, TimeSpan? capture
         /// <param name="input">Source video file.</param>
         /// <param name="captureTime">Seek position where the thumbnail should be taken.</param>
         /// <param name="size">Thumbnail size. If width or height equal 0, the other will be computed automatically.</param>
+        /// <param name="inputFileIndex">Input file index</param>
         /// <param name="streamIndex">Selected video stream index.</param>
         /// <returns>Bitmap with the requested snapshot.</returns>
-        public static async Task<Bitmap> SnapshotAsync(string input, Size? size = null, TimeSpan? captureTime = null, int streamIndex = 0)
+        public static async Task<Bitmap> SnapshotAsync(string input, Size? size = null, TimeSpan? captureTime = null, int inputFileIndex = 0, int? streamIndex = null)
         {
             var source = await FFProbe.AnalyseAsync(input);
-            var (arguments, outputOptions) = BuildSnapshotArguments(input, source, size, captureTime, streamIndex);
+            var (arguments, outputOptions) = BuildSnapshotArguments(input, source, size, captureTime, inputFileIndex, streamIndex);
             using var ms = new MemoryStream();
-            
+
             await arguments
                 .OutputToPipe(new StreamPipeSink(ms), options => outputOptions(options
                     .ForceFormat("rawvideo")))
@@ -102,17 +106,23 @@ await arguments
             return new Bitmap(ms);
         }
 
-        private static (FFMpegArguments, Action<FFMpegArgumentOptions> outputOptions) BuildSnapshotArguments(string input, IMediaAnalysis source, Size? size = null, TimeSpan? captureTime = null, int streamIndex = 0)
+        private static (FFMpegArguments, Action<FFMpegArgumentOptions> outputOptions) BuildSnapshotArguments(
+            string input,
+            IMediaAnalysis source,
+            Size? size = null,
+            TimeSpan? captureTime = null,
+            int inputFileIndex = 0,
+            int? streamIndex = null)
         {
             captureTime ??= TimeSpan.FromSeconds(source.Duration.TotalSeconds / 3);
             size = PrepareSnapshotSize(source, size);
-            var index = source.VideoStreams.FirstOrDefault(videoStream => videoStream.Index == streamIndex)?.Index;
+            streamIndex = streamIndex == null ? 0 : source.VideoStreams.FirstOrDefault(videoStream => videoStream.Index == streamIndex).Index;
 
             return (FFMpegArguments
                 .FromFileInput(input, false, options => options
-                    .Seek(captureTime)), 
+                    .Seek(captureTime)),
                 options => options
-                    .SelectStream(index ?? 0)
+                    .SelectStream((int)streamIndex, inputFileIndex)
                     .WithVideoCodec(VideoCodec.Png)
                     .WithFrameOutputCount(1)
                     .Resize(size));
@@ -122,11 +132,11 @@ private static (FFMpegArguments, Action<FFMpegArgumentOptions> outputOptions) Bu
         {
             if (wantedSize == null || (wantedSize.Value.Height <= 0 && wantedSize.Value.Width <= 0) || source.PrimaryVideoStream == null)
                 return null;
-            
+
             var currentSize = new Size(source.PrimaryVideoStream.Width, source.PrimaryVideoStream.Height);
             if (source.PrimaryVideoStream.Rotation == 90 || source.PrimaryVideoStream.Rotation == 180)
                 currentSize = new Size(source.PrimaryVideoStream.Height, source.PrimaryVideoStream.Width);
-            
+
             if (wantedSize.Value.Width != currentSize.Width || wantedSize.Value.Height != currentSize.Height)
             {
                 if (wantedSize.Value.Width <= 0 && wantedSize.Value.Height > 0)
diff --git a/FFMpegCore/FFMpeg/FFMpegArgumentOptions.cs b/FFMpegCore/FFMpeg/FFMpegArgumentOptions.cs
index 94b1cb2..1126471 100644
--- a/FFMpegCore/FFMpeg/FFMpegArgumentOptions.cs
+++ b/FFMpegCore/FFMpeg/FFMpegArgumentOptions.cs
@@ -48,11 +48,11 @@ public FFMpegArgumentOptions WithVideoFilters(Action<VideoFilterOptions> videoFi
         public FFMpegArgumentOptions WithSpeedPreset(Speed speed) => WithArgument(new SpeedPresetArgument(speed));
         public FFMpegArgumentOptions WithStartNumber(int startNumber) => WithArgument(new StartNumberArgument(startNumber));
         public FFMpegArgumentOptions WithCustomArgument(string argument) => WithArgument(new CustomArgument(argument));
-        
+
         public FFMpegArgumentOptions Seek(TimeSpan? seekTo) => WithArgument(new SeekArgument(seekTo));
         public FFMpegArgumentOptions Loop(int times) => WithArgument(new LoopArgument(times));
         public FFMpegArgumentOptions OverwriteExisting() => WithArgument(new OverwriteArgument());
-        public FFMpegArgumentOptions SelectStream(int index) => WithArgument(new MapStreamArgument(index));
+        public FFMpegArgumentOptions SelectStream(int streamIndex, int inputFileIndex = 0) => WithArgument(new MapStreamArgument(inputFileIndex, streamIndex));
 
         public FFMpegArgumentOptions ForceFormat(ContainerFormat format) => WithArgument(new ForceFormatArgument(format));
         public FFMpegArgumentOptions ForceFormat(string format) => WithArgument(new ForceFormatArgument(format));