I’m working on a C# project where I need to run FFmpeg commands to process videos. The FFmpeg command works perfectly fine when executed directly in the shell, but it hangs when run from my C# application. I suspect the issue is related to the output pipes getting full.

Here is the FFmpeg command I’m using:

shell
C:pathtoffmpeg.exe -f concat -safe 0 -i "C:pathtolist.txt" -vf "scale=1080x1920,setsar=1" -c:v libx264 -pix_fmt yuv420p -c:a aac -ar 44100 -ac 2 "C:pathtooutput.mp4"

And here is my C# code:

private static async Task _ExecuteFfmpegCommand(string arguments) {
    const string EXECUTABLE_NAME = "ffmpeg.exe";
    var executableFile = FfmpegPath.File(EXECUTABLE_NAME);
    await DownloadSercvice.EnsureFileExist(executableFile, FfmpegURI);
    arguments = $"-loglevel quiet {arguments}";

    using var process = new Process {
        StartInfo = new ProcessStartInfo {
            FileName = executableFile.FullName,
            Arguments = arguments,
            UseShellExecute = false,
            CreateNoWindow = true,
            RedirectStandardOutput = true,
            RedirectStandardError = true
        }
    };

    var command = $"{process.StartInfo.FileName} {process.StartInfo.Arguments}";
    Console.WriteLine($"This is my process command: {command}");

    var outputTask = new TaskCompletionSource<string>();
    var errorTask = new TaskCompletionSource<string>();

    process.OutputDataReceived += (sender, e) => {
        if (e.Data == null)            
            outputTask.SetResult(null);            
        else            
            Console.WriteLine(e.Data);            
    };

    process.ErrorDataReceived += (sender, e) => {
        if (e.Data == null)            
            errorTask.SetResult(null);            
        else            
            Console.WriteLine(e.Data);            
    };

    process.Start();
    process.BeginOutputReadLine();
    process.BeginErrorReadLine();

    await process.WaitForExitAsync();

    var output = await outputTask.Task;
    var error = await errorTask.Task;

    if (process.ExitCode != 0 || !string.IsNullOrWhiteSpace(error)) {
        throw new InvalidOperationException($"FFMPEG Error(0x{process.ExitCode:X8}): {error}") {
            Data = {
            { "Output", output },
            { "Error", error },
            { "ExitCode", process.ExitCode }
        }
        };
    }
}

Issue:
The process hangs and does not complete execution. I suspect the FFmpeg process’s output pipes (stdout and stderr) are getting full, causing the hang. I’ve tried setting the log level to error, but it didn’t resolve the issue.
I got that info from here: ffmpeg hangs when run in background
Solutions Tried:

Set -loglevel error in the FFmpeg command to reduce verbosity.
Set -loglever quiet in the FFmpeg command (to test if that may work)

Handled OutputDataReceived and ErrorDataReceived events to read the output asynchronously.
Questions:

How can I prevent the FFmpeg process from hanging due to full output pipes?
Are there better ways to handle the stdout and stderr of the FFmpeg process in C#?
Any help or suggestions on how to resolve this issue would be greatly appreciated!