ISSUE ABOUT LOG REDIRECTION
Hello all, first, in this beginning of year : my best wishes to all of you. I am using ffmpeg, both release 6.1, running on Windows 11 Family. In order to log what happens, I used to add at the end of the ffmpeg command line : 1>"file.log1" 2>"file.log2" So that the full command line looks like : ffmpeg -i "source file" <parameters> "destination file" 1>"file.log1" 2>"file.log2" In some cases (for some source files) it works fine ; and for another source files, I don't know why, the command execution produces the following error : [AVFormatContext @ 00000247c4bbd100] Unable to choose an output format for '1>file.log1'; use a standard extension for the filename or specify the format manually. [out#1 @ 00000247c46ceb00] Error initializing the muxer for 1>file.log1: Invalid argument Error opening output file 1>file.log1. Error opening output files: Invalid argument Does anyone has any idea for what causes this error ? Thank you in advance for your replies and advices. Regards, HA
On Fri, Jan 9, 2026 at 8:12 AM Hervé ANSELME via ffmpeg-user <ffmpeg-user@ffmpeg.org> wrote:
In some cases (for some source files) it works fine ; and for another source files, I don't know why, the command execution produces the following error :
[AVFormatContext @ 00000247c4bbd100] Unable to choose an output format for '1>file.log1'; use a standard extension for the filename or specify the format manually. [out#1 @ 00000247c46ceb00] Error initializing the muxer for 1>file.log1: Invalid argument Error opening output file 1>file.log1. Error opening output files: Invalid argument
Does anyone has any idea for what causes this error ?
I would suggest posting the full command line for the case that failed. My guess is that for some case you are trying to do it is missing the destination filename, which causes it to think that the 1>file.log.1 is the output filename. -- Devin Heitmueller, Senior Software Engineer LTN Global Communications o: +1 (301) 363-1001 w: https://ltnglobal.com e: devin.heitmueller@ltnglobal.com
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Devin Heitmueller -
Hervé ANSELME