0xFFFFFFFF could be a repeat code. So the IR sensor will return the key code one time then repeat the 0xFFFFFFFF as long as the key is held.
What version of the IRremote library do you have installed?
decode_results cmd;
Is code from an older version (< 3.0) of the library. Code written for the older IRremote versions may not work right with the new versions (> 3.0).
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Use the IDE autoformat tool (ctrl-t or Tools, Auto format) before posting code in a code block.
Please go back and fix your original post.