I'm trying to convert a file using the following command

ffmpeg.exe -i .\kme9le9xeaa31.png -c:v apng .\kme9le9xeaa31.png.cpy

But ffmpeg yields the following error that it is unable to determine output file format

Unable to find a suitable output format for '.\kme9le9xeaa31.png.cp'
.\kme9le9xeaa31.png.cp: Invalid argument

Considering that filename is just metadata and should not be taken at face value, should ffmpeg not interpret it? If not, how do you disable such behavior?

1 Answer 1


You can set output format explicitly, adding -f png before .\kme9le9xeaa31.png.cp. If -f is not set, ffmpeg will examine the filename for an extension and guess the format based on that. In your case, you have changed the extension to cp (the letters after the final dot), so ffmpeg can't guess the format. There's no way to set the output format based on the input.

  • Fair enough. Guess I have overlooked this in the documentation.
    – Dragas
    Jul 15, 2019 at 7:14
  • This helped me trouble shoot a typo in my extension.
    – FredFury
    Jul 23, 2019 at 6:12

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