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NAME |
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AnyEvent::MPV - remote control mpv (https://mpv.io) |
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|
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SYNOPSIS |
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use AnyEvent::MPV; |
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|
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DESCRIPTION |
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This module allows you to remote control mpv (a video player). It also |
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is an AnyEvent user, you need to make sure that you use and run a |
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supported event loop. |
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|
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There are other modules doing this, and I haven't looked much at them |
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other than to decide that they don't handle encodings correctly, and |
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since none of them use AnyEvent, I wrote my own. When in doubt, have a |
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look at them, too. |
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|
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Knowledge of the mpv command interface |
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<https://mpv.io/manual/stable/#command-interface> is required to use |
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this module. |
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|
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Features of this module are: |
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|
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uses AnyEvent, so integrates well into most event-based programs |
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supports asynchronous and synchronous operation |
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allows you to properly pass binary filenames |
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accepts data encoded in any way (does not crash when mpv replies with |
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non UTF-8 data) |
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features a simple keybind/event system |
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|
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OVERVIEW OF OPERATION |
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This module forks an mpv process and uses --input-ipc-client (or |
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equivalent) to create a bidirectional communication channel between it |
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and the mpv process. |
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|
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It then speaks the somewhat JSON-looking (but not really being JSON) |
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protocol that mpv implements to both send it commands, decode and handle |
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replies, and handle asynchronous events. |
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|
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Here is a very simple client: |
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|
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use AnyEvent; |
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use AnyEvent::MPV; |
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|
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my $videofile = "./xyzzy.mp4"; |
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|
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my $mpv = AnyEvent::MPV->new (trace => 1); |
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|
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$mpv->start ("--", $videofile); |
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|
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my $timer = AE::timer 2, 0, my $quit = AE::cv; |
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$quit->recv; |
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|
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This starts mpv with the two arguments "--" and $videofile, which it |
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should load and play. It then waits two seconds by starting a timer and |
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quits. The "trace" argument to the constructor makes mpv more verbose |
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and also prints the commands and responses, so you can have an idea what |
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is going on. |
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|
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In my case, the above example would output something like this: |
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|
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[uosc] Disabled because original osc is enabled! |
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mpv> {"event":"start-file","playlist_entry_id":1} |
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mpv> {"event":"tracks-changed"} |
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(+) Video --vid=1 (*) (h264 480x480 30.000fps) |
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mpv> {"event":"metadata-update"} |
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mpv> {"event":"file-loaded"} |
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Using hardware decoding (nvdec). |
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mpv> {"event":"video-reconfig"} |
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VO: [gpu] 480x480 cuda[nv12] |
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mpv> {"event":"video-reconfig"} |
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mpv> {"event":"playback-restart"} |
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|
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This is not usually very useful (you could just run mpv as a simple |
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shell command), so let us load the file at runtime: |
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|
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use AnyEvent; |
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use AnyEvent::MPV; |
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|
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my $videofile = "./xyzzy.mp4"; |
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|
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my $mpv = AnyEvent::MPV->new ( |
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trace => 1, |
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args => ["--pause", "--idle=yes"], |
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); |
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|
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$mpv->start; |
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$mpv->cmd_recv (loadfile => $mpv->escape_binary ($videofile)); |
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$mpv->cmd ("set", "pause", "no"); |
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|
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my $timer = AE::timer 2, 0, my $quit = AE::cv; |
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$quit->recv; |
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|
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This specifies extra arguments in the constructor - these arguments are |
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used every time you "->start" mpv, while the arguments to "->start" are |
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only used for this specific clal to0 "start". The argument --pause keeps |
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mpv in pause mode (i.e. it does not play the file after loading it), and |
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"--idle=yes" tells mpv to not quit when it does not have a playlist - as |
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no files are specified on the command line. |
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|
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To load a file, we then send it a "loadfile" command, which accepts, as |
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first argument, the URL or path to a video file. To make sure mpv does |
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not misinterpret the path as a URL, it was prefixed with ./ (similarly |
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to "protecting" paths in perls "open"). |
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|
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Since commands send *to* mpv are send in UTF-8, we need to escape the |
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filename (which might be in any encoding) using the "esscape_binary" |
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method - this is not needed if your filenames are just ascii, or |
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magically get interpreted correctly, but if you accept arbitrary |
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filenamews (e.g. from the user), you need to do this. |
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|
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The "cmd_recv" method then queues the command, waits for a reply and |
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returns the reply data (or croaks on error). mpv would, at this point, |
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load the file and, if everything was successful, show the first frame |
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and pause. Note that, since mpv is implement rather synchronously |
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itself, do not expect commands to fail in many circumstances - for |
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example, fit he file does not exit, you will likely get an event, but |
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the "loadfile" command itself will run successfully. |
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|
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To unpause, we send another command, "set", to set the "pause" property |
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to "no", this time using the "cmd" method, which queues the command, but |
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instead of waiting for a reply, it immediately returns a condvar that |
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cna be used to receive results. |
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|
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This should then cause mpv to start playing the video. |
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|
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It then again waits two seconds and quits. |
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|
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Now, just waiting two seconds is rather, eh, unuseful, so let's look at |
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receiving events (using a somewhat embellished example): |
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|
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use AnyEvent; |
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use AnyEvent::MPV; |
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|
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my $videofile = "xyzzy.mp4"; |
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|
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my $quit = AE::cv; |
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|
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my $mpv = AnyEvent::MPV->new ( |
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trace => 1, |
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args => ["--pause", "--idle=yes"], |
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on_event => sub { |
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my ($mpv, $event, $data) = @_; |
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|
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if ($event eq "start-file") { |
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$mpv->cmd ("set", "pause", "no"); |
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} elsif ($event eq "end-file") { |
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print "end-file<$data->{reason}>\n"; |
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$quit->send; |
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} |
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}, |
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); |
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|
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$mpv->start; |
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$mpv->cmd (loadfile => $mpv->escape_binary ($videofile)); |
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|
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$quit->recv; |
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|
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This example uses a global condvar $quit to wait for the file to finish |
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playing. Also, most of the logic is now in an "on_event" callback, which |
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receives an event name and the actual event object. |
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|
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The two events we handle are "start-file", which is emitted by mpv once |
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it has loaded a new file, and "end-file", which signals the end of a |
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file. |
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|
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In the former event, we again set the "pause" property to "no" so the |
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movie starts playing. For the latter event, we tell the main program to |
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quit by invoking $quit. |
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|
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This should conclude the basics of operation. There are a few more |
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examples later in the documentation. |
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|
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ENCODING CONVENTIONS |
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As a rule of thumb, all data you pass to this module to be sent to mpv |
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is expected to be in unicode. To pass something that isn't, you need to |
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escape it using "escape_binary". |
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|
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Data received from $mpv, however, is *not* decoded to unicode, as data |
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returned by mpv is not generally encoded in unicode, and the encoding is |
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usually unspecified. So if you receive data and expect it to be in |
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unicode, you need to first decode it from UTF-8, but note that this |
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might fail. This is not a limitation of this module - mpv simply does |
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not specify nor guarantee a specific encoding, or any encoding at all, |
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in its protocol. |
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|
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METHODS |
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$mpv = AnyEvent::MPV->new (key => value...) |
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Creates a new "mpv" object, but does not yet do anything. The |
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support key-value pairs are: |
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|
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mpv => $path |
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The path to the mpv binary to use - by default, "mpv" is used |
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and therefore, uses your "PATH" to find it. |
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|
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args => [...] |
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Arguments to pass to mpv. These arguments are passed after the |
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hardcoded arguments used by this module, but before the |
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arguments passed ot "start". It does not matter whether you |
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specify your arguments using this key, or in the "start" call, |
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but when you invoke mpv multiple times, typically the arguments |
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used for all invocations go here, while arguments used for |
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specific invocations (e..g filenames) are passed to "start". |
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|
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trace => false|true|coderef |
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Enables tracing if true. In trace mode, output from mpv is |
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printed to standard error using a "mpv>" prefix, and commands |
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sent to mpv are printed with a ">mpv" prefix. |
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|
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If a code reference is passed, then instead of printing to |
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standard errort, this coderef is invoked with a first arfgument |
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being either "mpv>" or ">mpv", and the second argument being a |
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string to display. The default implementation simply does this: |
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|
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sub { |
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warn "$_[0] $_[1]\n"; |
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} |
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|
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on_eof => $coderef->($mpv) |
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on_event => $coderef->($mpv, $event, $data) |
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on_key => $coderef->($mpv, $string) |
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These are invoked by the default method implementation of the |
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same name - see below. |
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|
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$string = $mpv->escape_binary ($string) |
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This module excects all command data sent to mpv to be in unicode. |
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Some things are not, such as filenames. To pass binary data such as |
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filenames through a comamnd, you need to escape it using this |
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method. |
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|
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The simplest example is a "loadfile" command: |
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|
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$mpv->cmd_recv (loadfile => $mpv->escape_binary ($path)); |
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|
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$started = $mpv->start (argument...) |
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Starts mpv, passing the given arguemnts as extra arguments to mpv. |
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If mpv is already running, it returns false, otherwise it returns a |
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true value, so you can easily start mpv on demand by calling "start" |
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just before using it, and if it is already running, it will not be |
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started again. |
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|
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The arguments passwd to mpv are a set of hardcoded built-in |
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arguments, followed by the arguments specified in the constructor, |
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followed by the arguments passwd to this method. The built-in |
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arguments currently are --no-input-terminal, --really-quiet (or |
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--quiet in "trace" mode), and "--input-ipc-client" (or equivalent). |
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|
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Some commonly used and/or even useful arguments you might want to |
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pass are: |
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|
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--idle=yes or --idle=once to keep mpv from quitting when you don't |
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specify a file to play. |
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--pause, to keep mpv from instantly starting to play a file, in case |
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you want to inspect/change properties first. |
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--force-window=no (or similar), to keep mpv from instantly opening a |
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window, or to force it to do so. |
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--audio-client-name=yourappname, to make sure audio streams are |
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associated witht eh right program. |
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--wid=id, to embed mpv into another application. |
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--no-terminal, --no-input-default-bindings, --no-input-cursor, |
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--input-conf=/dev/null, --input-vo-keyboard=no - to ensure only you |
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control input. |
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|
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The return value can be used to decide whether mpv needs |
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initializing: |
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|
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if ($mpv->start) { |
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$mpv->bind_key (...); |
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$mpv->cmd (set => property => value); |
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... |
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} |
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|
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You can immediately starting sending commands when this method |
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returns, even if mpv has not yet started. |
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|
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$mpv->stop |
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Ensures that mpv is being stopped, by killing mpv with a "TERM" |
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signal if needed. After this, you can "->start" a new instance |
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again. |
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|
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$mpv->on_eof |
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This method is called when mpv quits - usually unexpectedly. The |
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default implementation will call the "on_eof" code reference |
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specified in the constructor, or do nothing if none was given. |
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|
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For subclassing, see *SUBCLASSING*, below. |
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|
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$mpv->on_event ($event, $data) |
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This method is called when mpv sends an asynchronous event. The |
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default implementation will call the "on_event" code reference |
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specified in the constructor, or do nothing if none was given. |
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|
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The first/implicit argument is the $mpv object, the second is the |
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event name (same as "$data->{event}", purely for convenience), and |
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the third argument is the full event object as sent by mpv. See List |
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of events <https://mpv.io/manual/stable/#list-of-events> in its |
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documentation. |
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|
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For subclassing, see *SUBCLASSING*, below. |
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|
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$mpv->on_key ($string) |
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Invoked when a key declared by "->bind_key" is pressed. The default |
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invokes the "on_key" code reference specified in the constructor |
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with the $mpv object and the key name as arguments, or do nothing if |
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none was given. |
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|
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For more details and examples, see the "bind_key" method. |
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|
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For subclassing, see *SUBCLASSING*, below. |
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|
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$mpv->cmd ($command => $arg, $arg...) |
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Queues a command to be sent to mpv, using the given arguments, and |
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immediately return a condvar. |
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|
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See the mpv documentation |
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<https://mpv.io/manual/stable/#list-of-input-commands> for details |
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on individual commands. |
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|
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The condvar can be ignored: |
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|
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$mpv->cmd (set_property => "deinterlace", "yes"); |
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|
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Or it can be used to synchronously wait for the command results: |
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|
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$cv = $mpv->cmd (get_property => "video-format"); |
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$format = $cv->recv; |
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|
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# or simpler: |
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|
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$format = $mpv->cmd (get_property => "video-format")->recv; |
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|
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# or even simpler: |
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|
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$format = $mpv->cmd_recv (get_property => "video-format"); |
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|
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Or you can set a callback: |
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|
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$cv = $mpv->cmd (get_property => "video-format"); |
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$cv->cb (sub { |
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my $format = $_[0]->recv; |
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}); |
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|
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On error, the condvar will croak when "recv" is called. |
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|
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$result = $mpv->cmd_recv ($command => $arg, $arg...) |
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The same as calling "cmd" and immediately "recv" on its return |
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value. Useful when you don't want to mess with mpv asynchronously or |
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simply needs to have the result: |
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|
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$mpv->cmd_recv ("stop"); |
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$position = $mpv->cmd_recv ("get_property", "playback-time"); |
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|
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$mpv->bind_key ($INPUT => $string) |
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This is an extension implement by this module to make it easy to get |
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key events. The way this is implemented is to bind a |
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"client-message" witha first argument of "AnyEvent::MPV" and the |
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$string you passed. This $string is then passed ot the "on_key" |
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handle when the key is proessed, e.g.: |
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|
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my $mpv = AnyEvent::MPV->new ( |
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on_key => sub { |
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my ($mpv, $key) = @_; |
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|
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if ($key eq "letmeout") { |
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print "user pressed escape\n"; |
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} |
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}, |
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); |
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|
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$mpv_>bind_key (ESC => "letmeout"); |
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|
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The key configuration is lost when mpv is stopped and must be |
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(re-)done after every "start". |
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|
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SUBCLASSING |
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Like most perl objects, "AnyEvent::MPV" objects are implemented as |
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hashes, with the constructor simply storing all passed key-value pairs |
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in the object. If you want to subclass to provide your own "on_*" |
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methods, be my guest and rummage around in the internals as much as you |
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wish - the only guarantee that this module dcoes is that it will not use |
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keys with double colons in the name, so youc an use those, or chose to |
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simply not care and deal with the breakage. |
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|
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If you don't want to go to the effort of subclassing this module, you |
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can also specify all event handlers as constructor keys. |
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|
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SEE ALSO |
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AnyEvent, the mpv command documentation |
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<https://mpv.io/manual/stable/#command-interface>. |
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|
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AUTHOR |
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Marc Lehmann <schmorp@schmorp.de> |
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http://home.schmorp.de/ |
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|
