When rendering to get an MP4 output in Unreal, I’m encountering an error like the one below. I’ve watched all the videos related to ffmpeg installation, but it’s not working.
“Command Line Encoder: [concat @ 000001ecc90360c0] Line 1: unknown keyword ‘?f’
C:/Users/bekta/OneDrive/Masaüstü/Unreal Engine/EnvironmentProject/Content/6E5E6A004F5560E6B5A669A7058645CD_input.txt: Invalid data found when processing input”
I had the same problem.
In my case, this problem occurred when the destination folder contained Japanese (multi-byte) characters.
I solved the problem by making the path to the output folder alphabetical only.
i have the same problem. And the ouput folder already is alphabetical only. Anyone knows the solution?
I checked the XXXXXXXXXXXXXX_input.txt file.
When the path contains only alphabetical characters, the TXT file uses UTF-8 encoding. However, when the path contains Unicode characters, the TXT file uses UTF-16LE encoding, which prevents ffmpeg from reading it.
I had the same issue, but later discovered that renaming my sequencer to use English characters resolved the problem.Additionally, make sure to remove the renamed sequencer from the Movie Rendering Queue and re-add it afterward—this step is crucial!.Sharing this here in case it helps others who encounter this error through online searches—this might be a potential fix!
( translated via translation software, but I’ve refined it for clarity 
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