Process stalls when launched in .NET (ffmpeg)

Question

I'm trying to launch ffmpeg as a Process in .NET (C#), but in some cases, depending on the arguments (specifically, if I omit video arguments in order to create an audio file), it's stalling. It launches, outputs some lines, but then just stalls (using 0% CPU). When the parent .NET process is killed, it continues, and if I let it continue, ffmpeg produces the file correctly. I thought it might be due to using Peek() to look at the stream, so I just simplified it to the following, which behaves the same:

_process = new Process
{
    StartInfo =
    {
        UseShellExecute = false,
        RedirectStandardOutput = false,
        RedirectStandardError = true,
        FileName = "c:\\ffmpeg.exe",
        Arguments = string.Format(
    "-i {0} {1} {2} {3} -y {4}", inputPath, videoArgs, audioArgs, options, outputPath)
    }
};
_process.Start();
_process.WaitForExit();

ffmpeg gets to the point where it outputs information about the input video/audio streams before stalling. Executing the command via the command prompt works as expected.

Does anyone know what the problem could be?

Edit:

Just to add, I tried UseShellExecute = true (and RedirectStandardError = false), and this works. I still need to read the output, however, so this doesn't really help me.

Answer 1

Have a read of this MSDN on RedirectStandardError

Apparently this is a bit fiddly and can deadlock if the output or error stream buffers get filled up. Sit's there waiting for you to read what it's wrote...