Redirect FFmpeg Error Logs to a Text File on Windows

This article provides a straightforward guide on how to redirect FFmpeg’s error logs and command output to a text file on Windows. You will learn the specific Command Prompt syntax required to capture these logs, which is essential for troubleshooting and debugging your video and audio processing tasks.

By default, FFmpeg writes its console output and error logs to the “standard error” stream (stderr) rather than the “standard output” stream (stdout). Because of this, standard Windows redirection tools need to be configured specifically to capture this stream.

Step 1: Open Command Prompt

Press the Windows Key, type cmd, and press Enter to open the Command Prompt. Navigate to the folder where your files and FFmpeg are located using the cd command if necessary.

Step 2: Run the Redirection Command

To redirect the FFmpeg log output to a text file, use the standard error redirection operator 2>.

Run the following command:

ffmpeg -i input.mp4 output.mp4 2> error_log.txt

In this command: * ffmpeg -i input.mp4 output.mp4 is your standard FFmpeg command. * 2> tells Windows to redirect the stderr stream (stream number 2). * error_log.txt is the name of the file where the logs will be saved. If the file does not exist, Windows will create it. If it does exist, it will be overwritten.

Redirecting and Appending Logs

If you want to run multiple FFmpeg commands and append the log results to the end of the same text file without overwriting previous data, use the 2>> operator:

ffmpeg -i input.mp4 output.mp4 2>> error_log.txt

Redirecting Both Output and Errors

If you want to capture both the standard output (stdout) and the error logs (stderr) into a single text file, redirect stream 2 to stream 1 using the following syntax:

ffmpeg -i input.mp4 output.mp4 > complete_log.txt 2>&1

Once the command finishes executing, you will find the generated .txt file in your current working directory containing the complete log output from your FFmpeg session.