Get Unable to cast object of type 'FFmpeg.NET.MediaFile' to type 'FFmpeg.NET.InputFile' error when trying to cut video file.

[zydjohnHotmail]

Hello: I want to see if I can use this repo to cut one video (mp4 format). I created one C# WinForms project (target .NET 5.0), add nuget package: Install-Package xFFmpeg.NET -Version 6.0.0 The following is my C# code: using FFmpeg.NET; using System.IO;

public static async Task FFMPEG_Cut_Video1(string input_file1, string output_file1) { try { if (!File.Exists(input_file1)) { Debug.Print("Input video not found, quit!"); return "FileNOTFound"; } MediaFile video_in = new(input_file1); MediaFile video_out = new(output_file1); Engine ffmpeg = new(FFMPEG_Engine); ConversionOptions options = new(); options.CutMedia(TimeSpan.FromSeconds(30), TimeSpan.FromSeconds(25)); await ffmpeg.ConvertAsync((InputFile)video_in, (OutputFile)video_out, options); } catch (InvalidCastException ex) { Debug.Print(ex.Message); } return "Cut_OK"; }

private async void Form1_Load(object sender, EventArgs e) { await FFMPEG_Cut_Video1("C:\Videos\1.mp4", "C:\Videos\cut1.mp4"); }

However, when I run my code, I got the following error: System.InvalidCastException HResult=0x80004002 Message=Unable to cast object of type 'FFmpeg.NET.MediaFile' to type 'FFmpeg.NET.InputFile'. Source=System.Private.CoreLib StackTrace: at System.Runtime.CompilerServices.CastHelpers.ChkCast_Helper(Void toTypeHnd, Object obj) at System.Runtime.CompilerServices.CastHelpers.ChkCastClassSpecial(Void toTypeHnd, Object obj) at B20VideoSeekerSportRadarForm.Form1.d__7.MoveNext() in C:\Videos\VideoCut\Form1.cs:line 89 at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult() at B20VideoSeekerSportRadarForm.Form1.d__8.MoveNext() in C:\Videos\VideoCut\Form1.cs:line 97

This exception was originally thrown at this call stack: B20VideoSeekerSportRadarForm.Form1.FFMPEG_Cut_Video1(string, string) in Form1.cs [External Code] B20VideoSeekerSportRadarForm.Form1.Form1_Load(object, System.EventArgs) in Form1.cs Please advise how I can fix this? Using ffmpeg command, I can cut the video file, but I would like to use API in my C# program. PS: I am using Windows 10 (Version 21H1), and Visual Studio 2019 (Version 16.10.4) Thanks,

[DaveCS1]

Your code MediaFile video_in = new(input_file1); MediaFile video_out = new(output_file1); needs to look as such MediaFile video_in = new MediaFile(input_file1); MediaFile video_out = new MediaFile(output_file1);

That's why you received the type mismatch error.

//ffmpegPath is your path to ffmpeg.exe. eg "c:\ffmpeg\ffmpeg.exe" public async Task MakeVideoSegment(string input, string output, string ffmpegPath, int TrimStart, int TrimEnd) { var inputFile = new MediaFile(input); var outputFile = new MediaFile(output); var ffmpeg = new FFmpeg.NET.Engine(ffmpegPath); var options = new ConversionOptions(); int SecondsToTrim = TrimEnd - TrimStart; options.CutMedia(TimeSpan.FromSeconds(TrimStart), TimeSpan.FromSeconds(SecondsToTrim)); await ffmpeg.ConvertAsync(inputFile, outputFile, options); TrimmedFileNameFullPath = outputFile.FileInfo.FullName.ToString(); return TrimmedFileNameFullPath;

    }

[cmxl]

Use InputFile and OutputFile instead of MediaFile. MediaFile will now actually become an abstract class and does not implement IInputArguments which is used by ConvertAsync.

var inputFile = new InputFile(@"C:\Path\To_Video.flv");
var outputFile = new OutputFile(@"C:\Path\To_Save_ExtractedVideo.flv");
var ffmpeg = new Engine("C:\ffmpeg\ffmpeg.exe");
var options = new ConversionOptions();
options.CutMedia(TimeSpan.FromSeconds(30), TimeSpan.FromSeconds(25));
await ffmpeg.ConvertAsync(inputFile, outputFile, options, default);