Parameters Explanation,
-f concat -safe 0 -i inputs.txt: Uses the concat demuxer to read the list of files.
-i audio.mp3: Inputs the single audio file.
-c:v copy: Stream copies the video (fast, no re-encoding).
-c:a aac: Re-encodes audio to AAC for better compatibility with MP4.
-map 0:v:0 -map 1:a:0: Takes the video from the first input (concat) and audio from the second input.
-shortest: Ends the output file when the shortest input (likely the audio) finishes.