AVI files playing sound but no video

as above: AVI files inserted into Writer document play sound but no vision. Is this a missing codec? If so, where do I get one? And why doesn’t either Windows or the media player say so, rather than simply staying quiet?

(Environment: Windows 10, 64-bit; default player is VLC, but I suspect that Writer doesn’t make use of that, since the files are played OK if submitted directly to VLC)

Can this help?

[Media Support](https://wiki.documentfoundation.org/Media_Support)

Insert Video

Audio or Video