If this is not being done on a CF Humax T2, there is another forum that would be more appropriate. In any case, show the console log of the failed or unsatisfactory command including the original command, to document the usage of the twisty little ffmpeg options, many alike. And some ffprobe or mediainfo output for the before and after streams may be useful.
Also, ffmpeg v8.0, but it's not obviously going to make any difference here.
Also, ffmpeg v8.0, but it's not obviously going to make any difference here.