A vague idea to get something similar what libquvi did.
Undocumented because it might change a lot, or even be removed. To give
an idea what it does, a Lua script could do the following:
-- type ID priority
mp.commandv("hook_add", "on_load", 0, 0)
mp.register_script_message("hook_run", function(param, param2)
-- param is "0", the user-chosen ID from the hook_add command
-- param2 is the magic value that has to be passed to finish
-- the hook
mp.resume_all()
-- do something, maybe set options that are reset on end:
mp.set_property("file-local-options/name", "value")
-- or change the URL that's being opened:
local url = mp.get_property("stream-open-filename")
mp.set_property("stream-open-filename", url .. ".png")
-- let the player (or the next script) continue
mp.commandv("hook_ack", param2)
end)
Internally, there are two mechanisms which can trigger property
notification as used with "observed" properties in the client API.
The first mechanism associates events with a group of properties that
are potentially changed by a certain event. mp_event_property_change[]
declares these associations, and maps each event to a set of strings.
When an event happens, the set of strings is matched against the list of
observed properties of each client. Make this more efficient by
comparing bitsets of events instead. This way, only a bit-wise "and" is
needed for each observed property. Even better, we can completely skip
clients which have no observed properties that match.
The second mechanism just updates individual properties explicitly by
name. Optimize this by using the property index instead. It would be
nice if we could reuse the first mechanism for the second one, but
there are too many properties to fit into a 64 bit mask.
(Though the limit on 64 events might get us into trouble later...)
Achieve this by polling. Will be used by the OSC. Basically a bad hack -
but the point is that the mpv core itself is in the best position to
improve this later.
Instead of absuing m_option to store the property list, introduce a
separate type for properties. m_option is still used to handle data
types. The property declaration itself now never contains the option
type, and instead it's always queried with M_PROPERTY_GET_TYPE. (This
was already done with some properties, now all properties use it.)
This also fixes that the function signatures did not match the function
type with which these functions were called. They were called as:
int (*)(const m_option_t*, int, void*, void*)
but the actual function signatures were:
int (*)(m_option_t*, int, void*, MPContext *)
Two arguments were mismatched.
This adds one line per property implementation. With additional the
reordering of the parameters, this makes most of the changes in this
commit.
Until now, an error was reported only if the command couldn't be parsed.
Attempt to do more fine-grained reporting. This is not necessarily
perfect, but it's an improvement.
This turned out ridiculously complex. I think it will have to be
simplified some day. Main reason for the complexity are:
- filtering properties by forcing clients to observe individual
properties explicitly
(to avoid spamming clients with changes they don't want)
- optional retrieval of property value with the notification
(the basic idea was that this is more user friendly)
- allowing to the client to specify a format in which the value
should be retrieved
(because if a property changes its type, the client API couldn't
convert it properly, and compatibility would break)
I don't know yet which of these are important, and everything could
change. In particular, the interface and semantics should be adjusted
to reduce the implementation complexity.
While I consider the API complete, there could (and probably will) be
bugs left. Also while the implementation is complete, it's inefficient.
The complexity of the property matching is O(a*b*c) with a clients,
b observed properties, and c properties changing at once. I threw away
an earlier implementation using bitmasks, because it was too unwieldy.
M_OPT_PARSE_ESCAPES was pretty stupid, and broke the (useful) assumption
that string variables contain exactly the same value as set by the
option. Simplify it, and move escape handling to the place where it's
used.
Escape handling itself is not terribly useful, but still allows useful
things like multiline custom OSD with "\n".
This is partial only, and it still accesses some MPContext internals.
Specifically, chapter and track lists are still read directly, and OSD
access is special-cased too.
The OSC seems to work fine, except using the fast-forward/backward
buttons. These buttons behave differently, because the OSC code had
certain assumptions how often its update code is called.
The Lua interface changes slightly.
Note that this has the odd property that Lua script and video start
at the same time, asynchronously. If this becomes an issue, explicit
synchronization could be added.
Add a client API, which is intended to be a stable API to get some rough
control over the player. Basically, it reflects what can be done with
input.conf commands or the old slavemode. It will replace the old
slavemode (and enable the implementation of a new slave protocol).
wm4