Cache and "live"/still downloading files playback

[Carl-Robert]

I am trying to solve an issue with --cache=yes --demuxer-max-bytes= not dealing well with files that are still downloading to the disk during playback.

How do I keep a large cache to avoid busy I/O interruptions while avoiding the cache pitfalls where the file is "fully cached", but still downloading? Now the playback stops at the end of the file at the time cache got filled (basically if the file is 400mb, cache 500mb then even if the file keeps downloading mpv sees it as a completed 400mb file until I quit and re-open the file). This is even worse with files that aren't downloaded sequentially, but in parts: the cache doesn't count for any downloaded content between cached parts of the video, causing skips even if the content is downloaded meanwhile.

With cache disabled mpv keeps reading the file and continuing playback normally until the download is finished and coming to the real end of file. Any partially downloaded files skip only when there truly is no content in those parts.

I did not file an issue for this, because this feels like the intended function and not a bug. I am looking for workarounds or trips/tricks from the community. Sadly I can't fix the I/O issues without at least some sort of extended buffer.