The idea seems nice but it kind of presumes that the user knows what the options are to input them into the program. This kind of seems like it should be a wizard, e.g.
./av1an-command-gen
Enter the video width. Common values include 3840 , 1920, 1280.
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Enter the video height. Common values include 2160, 1080, 720.
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Desired framerate. Enter 0 for same as source:
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Which encoder would you like? rav1e, svt, or aom?
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What speed would you like to choose?
Faster might mean lower quality. The available options are [ ... ].
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What is your target bitrate?
Higher values mean higher video quality but also a larger video size. The available options are [ ... ].
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This isn't a feature request, just a passerby suggestion. Actually, what it really could be is just a simple static hosted page on github pages.