Nextcloud 29.0 found that mp4 cannot generate preview images, others can be generated by ffmpeg
āenabledPreviewProvidersā =>
array (
0 => āOC\Preview\TXTā,
1 => āOC\Preview\MarkDownā,
2 => āOC\Preview\OpenDocumentā,
3 => āOC\Preview\PDFā,
4 => āOC\Preview\MSOffice2003ā,
5 => āOC\Preview\MSOfficeDocā,
6 => āOC\Preview\Imageā,
7 => āOC\Preview\Photoshopā,
8 => āOC\Preview\TIFFā,
9 => āOC\Preview\SVGā,
10 => āOC\Preview\Fontā,
11 => āOC\Preview\MP3ā,
12 => āOC\Preview\Movieā,
13 => āOC\Preview\MKVā,
14 => āOC\Preview\MP4ā,
15 => āOC\Preview\AVIā,
),
hi
I have the same problem as you