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MPV.pm  view on Meta::CPAN

It also doesn't use complicated command line arguments - the file search
options have the most impact, as they prevent F<mpv> from scanning
directories with tens of thousands of files for subtitles and more:

   --audio-client-name=doomfrontend
   --osd-on-seek=msg-bar --osd-bar-align-y=-0.85 --osd-bar-w=95
   --sub-auto=exact --audio-file-auto=exact

Since it runs on a TV without a desktop environemnt, it tries to keep complications such as dbus
away and the screensaver happy:

   # prevent xscreensaver from doing something stupid, such as starting dbus
   $ENV{DBUS_SESSION_BUS_ADDRESS} = "/"; # prevent dbus autostart for sure
   $ENV{XDG_CURRENT_DESKTOP} = "generic";

It does bind a number of keys to internal (to doomfrontend) commands:

   for (
      List::Util::pairs qw(
         ESC   return
         q     return
         ENTER enter
         SPACE pause
         [     steprev
         ]     stepfwd
         j     subtitle
         BS    red
         i     green
         o     yellow
         b     blue
         D     triangle
         UP    up
         DOWN  down
         RIGHT right
         LEFT  left
      ),
      (map { ("KP$_" => "num$_") } 0..9),
      KP_INS => 0, # KP0, but different
   ) {
      $mpv->bind_key ($_->[0] => $_->[1]);
   }

It also reacts to sponsorblock chapters, so it needs to know when vidoe
chapters change. Preadting C<AnyEvent::MPV>, it handles observers
manually:

   $mpv->cmd (observe_property => 1, "chapter-metadata");

It also tries to apply an F<mpv> profile, if it exists:

   eval {
      # the profile is optional
      $mpv->cmd ("apply-profile" => "doomfrontend");
   };

Most of the complicated parts deal with saving and restoring per-video
data, such as bookmarks, playing position, selected audio and subtitle
tracks and so on. However, since it uses L<Coro>, it can conveniently
block and wait for replies, which is n ot possible in purely event based
programs, as you are not allowed to block inside event callbacks in most
event loops. This simplifies the code quite a bit.

When the file to be played is a Tv recording done by mythtv, it uses the
C<appending> protocol and deinterlacing:

   if (is_myth $mpv_path) {
      $mpv_path = "appending://$mpv_path";
      $initial_deinterlace = 1;
   }

Otherwise, it sets some defaults and loads the file (I forgot what the
C<dummy> argument is for, but I am sure it is needed by some F<mpv>
version):

   $mpv->cmd ("script-message", "osc-visibility", "never", "dummy");
   $mpv->cmd ("set", "vid", "auto");
   $mpv->cmd ("set", "aid", "auto");
   $mpv->cmd ("set", "sid", "no");
   $mpv->cmd ("set", "file-local-options/chapters-file", $mpv->escape_binary ("$mpv_path.chapters"));
   $mpv->cmd ("loadfile", $mpv->escape_binary ($mpv_path));
   $mpv->cmd ("script-message", "osc-visibility", "auto", "dummy");

Handling events makes the main bulk of video playback code. For example,
various ways of ending playback:

      if ($INPUT eq "mpv/quit") { # should not happen, but allows user to kill etc. without consequence
         $status = 1;
         mpv_init; # try reinit
         last;

      } elsif ($INPUT eq "mpv/idle") { # normal end-of-file
         last;

      } elsif ($INPUT eq "return") {
         $status = 1;
         last;

Or the code that actually starts playback, once the file is loaded:

   our %SAVE_PROPERTY = (aid => 1, sid => 1, "audio-delay" => 1);
   
   ...

   my $oid = 100;

      } elsif ($INPUT eq "mpv/file-loaded") { # start playing, configure video
         $mpv->cmd ("seek", $playback_start, "absolute+exact") if $playback_start > 0;

         my $target_fps = eval { $mpv->cmd_recv ("get_property", "container-fps") } || 60;
         $target_fps *= play_video_speed_mult;
         set_fps $target_fps;

         unless (eval { $mpv->cmd_recv ("get_property", "video-format") }) {
            $mpv->cmd ("set", "file-local-options/lavfi-complex", "[aid1] asplit [ao], showcqt=..., format=yuv420p [vo]");
         };

         for my $prop (keys %SAVE_PROPERTY) {
            if (exists $PLAYING_STATE->{"mpv_$prop"}) {
               $mpv->cmd ("set", "$prop", $PLAYING_STATE->{"mpv_$prop"} . "");
            }

MPV.pm  view on Meta::CPAN

      "--audio-client-name=CV",

      "--osc=yes", # --osc=no displays fading play/pause buttons instead

      "--wid=$xid",
   );

   $self->{mpv}->cmd ("script-message" => "osc-visibility" => "never", "dummy");
   $self->{mpv}->cmd ("osc-idlescreen" => "no");

It also prepares a hack to force a ConfigureNotify event on every vidoe
reconfig:

   # force a configurenotify on every video-reconfig
   $self->{mpv_reconfig} = $self->{mpv}->register_event (video_reconfig => sub {
      my ($mpv, $event, $data) = @_;

      $self->mpv_window_update;
   });

The way this is done is by doing a "dummy" resize to 1x1 and back:

   $self->{mpv_window}->window->resize (1, 1),
   $self->{mpv_window}->window->resize ($self->{w}, $self->{h});

Without this, F<mpv> often doesn't "get" the correct window size. Doing
it this way is not nice, but I didn't fine a nicer way to do it.

When no file is being played, F<mpv> is hidden and prepared:

   $self->{mpv_eventbox}->hide;

   $self->{mpv}->cmd (set_property => "pause" => "yes");
   $self->{mpv}->cmd ("playlist_remove", "current");
   $self->{mpv}->cmd (set_property => "video-rotate" => 0);
   $self->{mpv}->cmd (set_property => "lavfi-complex" => "");

Loading a file is a bit more complicated, as bluray and DVD rips are
supported:

   if ($moviedir) {
      if ($moviedir eq "br") {
         $mpv->cmd (set => "bluray-device" => $path);
         $mpv->cmd (loadfile => "bd://");
      } elsif ($moviedir eq "dvd") {
         $mpv->cmd (set => "dvd-device" => $path);
         $mpv->cmd (loadfile => "dvd://");
      }
   } elsif ($type eq "video/iso-bluray") {
      $mpv->cmd (set => "bluray-device" => $path);
      $mpv->cmd (loadfile => "bd://");
   } else {
      $mpv->cmd (loadfile => $mpv->escape_binary ($path));
   }

After this, C<Gtk2::CV> waits for the file to be loaded, video to be
configured, and then queries the video size (to resize its own window)
and video format (to decide whether an audio visualizer is needed for
audio playback). The problematic word here is "wait", as this needs to be
imploemented using callbacks.

This made the code much harder to write, as the whole setup is very
asynchronous (C<Gtk2::CV> talks to the command interface in F<mpv>, which
talks to the decode and playback parts, all of which run asynchronously
w.r.t. each other. In practise, this can mean that C<Gtk2::CV> waits for
a file to be loaded by F<mpv> while the command interface of F<mpv> still
deals with the previous file and the decoder still handles an even older
file). Adding to this fact is that Gtk2::CV is bound by the glib event
loop, which means we cannot wait for replies form F<mpv> anywhere, so
everything has to be chained callbacks.

The way this is handled is by creating a new empty hash ref that is unique
for each loaded file, and use it to detect whether the event is old or
not, and also store C<AnyEvent::MPV> guard objects in it:

   # every time we loaded a file, we create a new hash
   my $guards = $self->{mpv_guards} = { };

Then, when we wait for an event to occur, delete the handler, and, if the
C<mpv_guards> object has changed, we ignore it. Something like this:

   $guards->{file_loaded} = $mpv->register_event (file_loaded => sub {
      delete $guards->{file_loaded};
      return if $guards != $self->{mpv_guards};

Commands do not have guards since they cnanot be cancelled, so we don't
have to do this for commands. But what prevents us form misinterpreting
an old event? Since F<mpv> (by default) handles commands synchronously,
we can queue a dummy command, whose only purpose is to tell us when all
previous commands are done. We use C<get_version> for this.

The simplified code looks like this:

   Scalar::Util::weaken $self;

   $mpv->cmd ("get_version")->cb (sub {

      $guards->{file_loaded} = $mpv->register_event (file_loaded => sub {
         delete $guards->{file_loaded};
         return if $guards != $self->{mpv_guards};

         $mpv->cmd (get_property => "video-format")->cb (sub {
            return if $guards != $self->{mpv_guards};

            # video-format handling
            return if eval { $_[0]->recv; 1 };

            # no video? assume audio and visualize, cpu usage be damned
            $mpv->cmd (set => "lavfi-complex" => ...");
         });

         $guards->{show} = $mpv->register_event (video_reconfig => sub {
            delete $guards->{show};
            return if $guards != $self->{mpv_guards};

            $self->{mpv_eventbox}->show_all;

            $w = $mpv->cmd (get_property => "dwidth");
            $h = $mpv->cmd (get_property => "dheight");

            $h->cb (sub {
               $w = eval { $w->recv };
               $h = eval { $h->recv };

               $mpv->cmd (set_property => "pause" => "no");

               if ($w && $h) {
                  # resize our window
               }