Combine audio and video files with FFMPEG in C#

Question

I'm currently trying to combine two files, one audio, and one video, in my C# program using FFMPEG with the following code:

ProcessStartInfo startInfo = new ProcessStartInfo();
startInfo.CreateNoWindow = false;
startInfo.FileName = "ffmpeg.exe";
startInfo.Arguments = "ffmpeg -i video.mp4 -i mic.wav -c:v copy -map 0:v:0 -map 1:a:0 -c:a aac -b:a 192k output.mp4";
using (Process exeProcess = Process.Start(startInfo))
{
    exeProcess.WaitForExit();
}

My debug folder is set up like this:

So I don't get any runtime errors, however, it just doesn't create the final output.mp4 file that I need it to.

What is shown in a Command Prompt when you run the ffmpeg command? — Jeremy Thompson
– Jeremy Thompson, Commented Dec 4, 2018 at 0:42
I don't get a chance to see it. It just pops up and then closes down — TermSpar
– TermSpar, Commented Dec 4, 2018 at 0:43
However if I run the command just in Command Prompt it performs the merge. — TermSpar
– TermSpar, Commented Dec 4, 2018 at 1:08
Oh to keep a Cmd Prompt open specify the /k switch. I think you might need to CD (aka Change Directory) - I see you have ffmpeg.exe in the debug folder - so it looks good. What we will get to eventually is reading the stdout from ffmpeg into C# to diagnose the root cause. See here mathewsachin.github.io/blog/2017/07/28/ffmpeg-pipe-csharp.html — Jeremy Thompson
– Jeremy Thompson, Commented Dec 4, 2018 at 1:09

urmat abdykerimov · Accepted Answer · 2021-08-10 12:12:25Z

9

I ended up solving it by doing the following:

string args = "/c ffmpeg -i \"video.mp4\" -i \"mic.wav\" -shortest outPutFile.mp4";
ProcessStartInfo startInfo = new ProcessStartInfo();
startInfo.CreateNoWindow = false;
startInfo.FileName = "cmd.exe";
startInfo.WorkingDirectory = @"" + outputPath;
startInfo.Arguments = args;
using Process exeProcess = Process.Start(startInfo)

exeProcess.WaitForExit();

edited Aug 10, 2021 at 12:12

urmat abdykerimov

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answered Dec 4, 2018 at 2:53

TermSpar

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4 Comments

Jeremy Thompson Over a year ago

Try a few more times with the arguments in the parameter. Like I was saying there are some good examples I linked to in the SU thread. -c:v copy -map 0:v:0 -map 1:a:0 -c:a aac -b:a 192k are actually important. See here: stackoverflow.com/a/36324719/495455

musicinmusic Over a year ago

Hey @BenCompSci, I used your code and it generates the .mp4 file but it doesn't use the audio from the .wav file at all, it has still the same audio and has a bit less size than the input video, does this work for you? What could be the problem in my case? I downloaded ffmpeg.exe file and placed it in the Debug folder.

musicinmusic Over a year ago

Never mind, ended up using this and it works like a charm ""/c ffmpeg -i video.mp4 -i audio.mp3 -map 0:0 -map 1:0 -shortest output.mp4""

TermSpar Over a year ago

Ya, for me I had to use command prompt to run the command via adding FFMPEG to the path

urmat abdykerimov · Accepted Answer · 2021-08-11 04:00:56Z

1

For some reason answer given by TermSpar didn't work for me at all, code that worked for me:

ProcessStartInfo startInfo = new()
{
    CreateNoWindow = false,
    FileName = @"C:\Users\User\Documents\ffmpeg.exe",
    UseShellExecute = false,
    RedirectStandardOutput = true,
    RedirectStandardError = true,
    Arguments = string.Format(" -i {0} -i {1} -shortest {2} -y", @"C:\images\video.avi", @"C:\images\voice.wav", @"C:\images\result.avi")
};

using Process exeProcess = Process.Start(startInfo);

//debug
string StdOutVideo = exeProcess.StandardOutput.ReadToEnd();
string StdErrVideo = exeProcess.StandardError.ReadToEnd();
//

exeProcess.WaitForExit();
exeProcess.Close();

answered Aug 11, 2021 at 4:00

urmat abdykerimov

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1 Comment

Felipe Mateus Over a year ago

The TermSpar answer dont works for you because u are using the ffmeg.exe directory, if u using the cmd.exe the argument changes so "/c ffmpeg" isnt necessary.

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