This gets quoted later, so don't quote it first.
Signed-off-by: Felix Paul Kühne <fkuehne@videolan.org>

This makes it a little more obvious, instead of just saying that tools
are missing or too old.

Close #12744

Thanks to Ruito

Only start and stop media key support when needed (ressource-intensive).

close #12423

Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

Signed-off-by: Tristan Matthews <tmatth@videolan.org>

And drop all unused and useless code

Gets rid of the checkless and expecting in-order data
read functions.

BW measurement must be per stream as receive window/transfert
rate will differ relatively to chunk size. There's no real
way to get an accurate Max BW with such small files, but it
is still accurate to predict the BW for a download of same
size.

A validation cursor is introduced to qualify bitrates.
Cursor evolves within a window of summed download times.
Adds duration to window if > bitrate, and opposite.
  -PROBE_TIME << cursor << PROBE_TIME
Negative values makes harder to select previously unqualified
bitrates.
Stream quality will rank up quality only if next candidate has
filled its own window.
Stream reselection only occurs when cursor <= 0.
In that way, we can tolerate temporary bitrate lowering or increase
and avoid the hiccup reselection problems we had until now.

Gets rid of useless indirect access to chunks.
Uses time as chunk based instead of indexes.
Does not keep chunks on live stream.