This content originally appeared on DEV Community and was authored by Willem Janssen
Video conversion is one of those tasks developers often bump into—whether it’s for building a media app, preparing assets for streaming, or just automating format conversions. The good news is that you don’t have to reinvent the wheel: FFmpeg is the industry standard for working with audio and video.
In this tutorial, we’ll build a simple command-line video converter in .NET 8 that wraps FFmpeg. By the end, you’ll have a lightweight tool that can take input files, convert them to different formats, and even be extended for batch processing.
🛠 Prerequisites
- .NET 8 SDK installed
- FFmpeg installed and added to your system PATH
- Basic knowledge of C# and console apps
1. Create the Project
Open your terminal and create a new console app:
dotnet new console -n VideoConverter
cd VideoConverter
2. Add a Process Wrapper for FFmpeg
FFmpeg is a command-line tool, so the easiest way to use it from .NET is to call it via System.Diagnostics.Process.
Create a file FfmpegWrapper.cs:
using System.Diagnostics;
public static class FfmpegWrapper
{
public static void Convert(string inputPath, string outputPath, string format)
{
var args = $"-i \"{inputPath}\" \"{outputPath}.{format}\"";
var process = new Process
{
StartInfo = new ProcessStartInfo
{
FileName = "ffmpeg",
Arguments = args,
RedirectStandardError = true,
UseShellExecute = false,
CreateNoWindow = true
}
};
process.Start();
string result = process.StandardError.ReadToEnd();
process.WaitForExit();
if (process.ExitCode != 0)
{
throw new Exception($"FFmpeg failed: {result}");
}
}
}
3. Build the CLI Entry Point
Modify Program.cs:
class Program
{
static void Main(string[] args)
{
if (args.Length < 3)
{
Console.WriteLine("Usage: VideoConverter <input> <output> <format>");
return;
}
var input = args[0];
var output = args[1];
var format = args[2];
try
{
Console.WriteLine($"Converting {input} → {output}.{format} ...");
FfmpegWrapper.Convert(input, output, format);
Console.WriteLine("Conversion complete!");
}
catch (Exception ex)
{
Console.WriteLine($"Error: {ex.Message}");
}
}
}
4. Run the Converter
Build and run your app:
dotnet build
dotnet run -- sample.mp4 output avi
5. Extending the Tool
This is just the beginning! You can:
✅ Add batch conversion (loop through folders)
✅ Support audio extraction (e.g., convert to .mp3)
✅ Add preset quality settings (low/medium/high)
✅ Wrap this logic into a REST API for cloud-based conversion
🎯 Conclusion
In just a few lines of C# code, we’ve built a working command-line video converter powered by FFmpeg. With .NET 8 handling the CLI and FFmpeg doing the heavy lifting, you can now extend this into more advanced tools—or even the backend of your own media SaaS.
👉 Next step: consider adding GPU acceleration (NVENC, QuickSync, etc.) for lightning-fast conversions.
This content originally appeared on DEV Community and was authored by Willem Janssen
Willem Janssen | Sciencx (2025-09-30T08:22:44+00:00) How to Build a Command-Line Video Converter with .NET 8 and FFmpeg. Retrieved from https://www.scien.cx/2025/09/30/how-to-build-a-command-line-video-converter-with-net-8-and-ffmpeg/
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