This makes no sense to use with DVD/BD/DVB and some others, and these
streams happen to be unseekable.
Also, other kinds of unseekable streams (like reading from pipe) should
work, but will exhibit sketchy behavior if they need to seek. So just
disable it, and leave these problems to the memory cache (cache.c).
Since we have to be portable, our options for creating temporary files
are somewhat limited. tmpfile() happens to be available everywhere, so
use that. This function doesn't allow having a "visible" filename or
location, so we use the magic string "TMP" for this.
Happens when playing from a pipe.
Note that seeking forward doesn't work. It would be possible to create a
workaround for that by reading and skipping data until the target
position is reached (and writing the skipped data into the cache file),
but I'm not sure about that.
Fixes#928.
CC: @mpv-player/stable
For remarks, pretty much see the manpage additions. Could help with
network streams that require too much seeking (maybe), or might be
extended to help with the use case of watching and downloading a file
at the same time.
In general, it might be a useless feature and could be removed again.
wm4