How do I remux video to a different format Using the Python yt-dlp invocation?

[kylegustavo]

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• I'm asking a question and not reporting a bug or requesting a feature
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I've been looking at the python version of the command at https://github.com/yt-dlp/yt-dlp/blob/9ebac35577e61c3d25fafc959655fa3ab04ca7ef/yt_dlp/YoutubeDL.py, and I noticed there isn't a "remux-video" option. Looking closer at the code, however, it appears there should be a way to remux or recode a video using the 'postprocessors' argument, but it isn't clear to me how this should be used. I've tried using [{"key": "FFmpegVideoConvertor", "when": "post_process"}] or [{"key": "FFmpegVideoRemuxer", "when": "post_process"}], with the extension in the final_ext argument, but there are some issues. Any guidance on what options I should use to get a remux or recode from mp4 to other formats in place of --remux-video in the command line version, like mov and avi?

Provide verbose output that clearly demonstrates the problem

• Run your yt-dlp command with -vU flag added (yt-dlp -vU <your command line>)
• If using API, add 'verbose': True to YoutubeDL params instead
• Copy the WHOLE output (starting with [debug] Command-line config) and insert it below

Complete Verbose Output

No response

[bashonly]

use devscripts/cli_to_api.py

ydl_opts = {
    'final_ext': 'mp4',
    'postprocessors': [{
        'key': 'FFmpegVideoRemuxer',
        'preferedformat': 'mp4',
    }],
}