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Mediaplayer mit VLC

  |   Anke (encarsia)   |   Auch verfügbar in: English 

Mediaplayer mit LibVLC realisieren

VLC ist nicht nur ein Multimediaplayer, sondern auch ein Framework, zu dem Python-Bindings verfügbar sind. In diesem Beispiel wird analog zum GStreamer-Artikel ein einfacher Mediaplayer mittels LibVLC umgesetzt.

/images/20_vlc_player.thumbnail.png

LibVLC

Voraussetzung für die Verwendung ist die Installation der Python-Bindings. Diese sind unter der Paketbezeichnung python-vlc zu finden.

Glade

  • Darstellungsbereich der Mediendatei: Widget Gtk.DrawingArea

  • Steuerungselemente: Vor-/Zurückspulen (Gtk.Button), Pause (Gtk.Togglebutton)

  • Medienauswahl: Buttons, um Video- oder Bilddatei anzuzeigen

  • Playback manipulieren: Buttons zum Stummschalten und Drehen des Videos

Python

Player einrichten

Der VLC-Player wird initiiert, sobald das dazugehörige Widget, in diesem Fall also Gtk.DrawingArea gezeichnet wird. Dazu wird das Signal realize genutzt, das grundsätzlich für die Klasse der Widgets verfügbar ist.

vlcOptions = "--no-xlib"
win_id = widget.get_window().get_xid()
setup_player(vlcOptions)
vlcInstance = vlc.Instance(options)
player = vlcInstance.media_player_new()
player.set_xwindow(win_id)

Als Optionen können Kommandozeilenoptionen von VLC übergeben werden. Im Beispiel wird beim Klick auf den "Rotate"-Button das Bild um 180° gedreht. Der Player wird erneut initiiert und die zusätzliche Option --video-filter=transform{type=180} übergeben.

Medium abspielen

Wie auch der GStreamer-Player kann der VLC-Player viele Video-/Audio- oder Bild-Formate anzeigen bzw. abspielen.

player.set_mrl(file_url)
# Datei abspielen
player.play()
# Pause/Play-Schalter
player.pause()

Positionsanzeige

Die Umsetzung des Fortschrittsbalkens und die Nutzung als Schiebereglers gestaltet sich ziemlich einfach.

# Position abfragen
player.get_position()
# Position bestimmen
player.set_position(val)

Der Wertebereich liegt dabei zwischen 0 und 1. Das Problem bei diesen Funktionen ist, dass sie relativ ressourcenintensiv arbeiten und das Playback mitunter verruckelt ist. Die Lösung im hiesigen Beispiel besteht darin, get_position-Abfragen zu umgehen, indem die Regler-Position herangezogen wird.

Möglichkeiten und Limitierungen

Die Nutzung der LibVLC-Python-Bindings erweist sich als einfach und angesichts der GStreamer-Umsetzung als geradezu intuitiv. Auch das "Headerbar-Problem" besteht nicht.

Auf der anderen Seite greift man hier auf großes Projekt zurück, man muss VLC und die Python-Bindings installiert haben anstatt einfach das GStreamer-Modul aus dem GObject Introspection-Repository zu verwenden. Auch ist im Test der Ressourcenverbrauch von VLC gegenüber GStreamer größer.

Listings

Python

20_vlc_simpleplayer.py (Source)

#!/usr/bin/env python
# -*- coding: utf-8 -*-

import os
import subprocess
import sys
import time
import vlc

import gi
gi.require_version("Gtk", "3.0")
from gi.repository import Gtk, Gio, Gdk, GLib


class Handler:

    def on_play_here_realize(self, widget):
        vlcOptions = "--no-xlib"
        self.win_id = widget.get_window().get_xid()
        self.setup_player(vlcOptions)
        self.player.audio_set_mute(False)
        self.is_playing = False

    def on_rotate_toggled(self, widget):
        pos = self.player.get_position()
        self.player.stop()
        self.player.release()
        self.vlcInstance.release()
        if widget.get_active():
            vlcOptions = "--no-xlib --video-filter=transform{type=180}"
        else:
            vlcOptions = "--no-xlib"
        self.setup_player(vlcOptions)
        self.player.set_mrl(self.video)
        self.player.play()
        self.player.set_position(pos)
        if not self.is_playing:
            time.sleep(.05)
            self.player.pause()

    def setup_player(self, options):
        self.vlcInstance = vlc.Instance(options)
        self.player = self.vlcInstance.media_player_new()
        self.player.set_xwindow(self.win_id)

    def on_backward_clicked(self, widget):
        skip_pos = go.slider.get_value() - 10
        if skip_pos < 0:
            self.player.set_position(0)
            go.slider.set_value(0)
        else:
            self.player.set_position(skip_pos / 100)
            go.slider.set_value(skip_pos)

    def on_forward_clicked(self, widget):
        skip_pos = go.slider.get_value() + 10
        if skip_pos > 100:
            self.player.pause()
            self.player.set_position(0.99)
            go.slider.set_value(100)
        else:
            self.player.set_position(skip_pos / 100)
            go.slider.set_value(skip_pos)

    def on_playpause_togglebutton_toggled(self, widget):
        if widget.get_active():
            img = Gtk.Image.new_from_icon_name(Gtk.STOCK_MEDIA_PLAY,
                                               Gtk.IconSize.BUTTON)
            widget.set_property("image", img)
            self.is_playing = False
        else:
            img = Gtk.Image.new_from_icon_name(Gtk.STOCK_MEDIA_PAUSE,
                                               Gtk.IconSize.BUTTON)
            widget.set_property("image", img)
            self.is_playing = True
        self.player.pause()
        GLib.timeout_add(1000, self.update_slider)

    def on_vbutton_clicked(self, widget):
        self.video = "file://" + os.path.abspath("mediaplayer.avi")
        self.duration = go.get_duration(self.video)
        self.player.set_mrl(self.video)
        self.is_playing = True
        go.slider.set_value(0)
        go.obj("playpause_togglebutton").set_active(False)
        go.obj("playpause_togglebutton").set_sensitive(True)
        go.obj("mute").set_sensitive(True)
        go.obj("rotate").set_sensitive(True)
        self.player.play()
        GLib.timeout_add(1000, self.update_slider)

    def on_ibutton_clicked(self, widget):
        image = "file://" + os.path.abspath("mediaplayer.jpg")
        self.player.set_mrl(image)
        self.is_playing = False
        self.player.play()
        go.obj("playpause_togglebutton").set_sensitive(False)
        go.obj("mute").set_sensitive(False)
        go.obj("rotate").set_sensitive(False)

    def on_mute_toggled(self, widget):
        if widget.get_active():
            widget.set_label("Unmute")
        else:
            widget.set_label("Mute")
        self.player.audio_toggle_mute()

    def on_progress_change_value(self, widget, scroll, value):
        self.player.set_position(value / 100)
        widget.set_value(value)

    def update_slider(self):
        if not self.is_playing:
            return False # cancel timeout
        else:
            pos = go.slider.get_value()
            new_pos = (pos + 100 / self.duration)
            go.slider.set_value(new_pos)
            if new_pos > 100:
                self.is_playing = False
        return True # continue calling every x milliseconds


class VlcPlayer:

    def __init__(self):
        self.app = Gtk.Application.new("org.media.player", Gio.ApplicationFlags(0))
        self.app.connect("activate", self.on_app_activate)

    def on_app_activate(self, app):
        # setting up builder
        builder = Gtk.Builder()
        builder.add_from_file("20_vlc_player.glade")
        builder.connect_signals(Handler())
        self.obj = builder.get_object
        # slider position is float between 0..100
        self.slider = self.obj("progress")
        window = self.obj("window")
        window.set_application(app)
        window.show_all()

    def get_duration(self,video):
        command = ["ffprobe",
                   "-v", "error",
                   "-show_entries", "format=duration",
                   "-of", "default=noprint_wrappers=1:nokey=1",
                   video,
                   ]
        ffprobe_cmd = subprocess.run(command, stdout=subprocess.PIPE)
        # stdout of subprocess is byte variable, convert into float then into integer
        return int(float(ffprobe_cmd.stdout.decode()))

    def run(self, argv):
        self.app.run(argv)


go = VlcPlayer()
go.run(None)

Glade

20_vlc_player.glade (Source)

<?xml version="1.0" encoding="UTF-8"?>
<!-- Generated with glade 3.20.0 -->
<interface>
  <requires lib="gtk+" version="3.16"/>
  <object class="GtkAdjustment" id="adjustment">
    <property name="upper">100</property>
    <property name="step_increment">1</property>
    <property name="page_increment">10</property>
  </object>
  <object class="GtkImage" id="image1">
    <property name="visible">True</property>
    <property name="can_focus">False</property>
    <property name="stock">gtk-media-rewind</property>
  </object>
  <object class="GtkImage" id="image2">
    <property name="visible">True</property>
    <property name="can_focus">False</property>
    <property name="stock">gtk-media-forward</property>
  </object>
  <object class="GtkImage" id="image3">
    <property name="visible">True</property>
    <property name="can_focus">False</property>
    <property name="stock">gtk-media-pause</property>
  </object>
  <object class="GtkApplicationWindow" id="window">
    <property name="width_request">600</property>
    <property name="height_request">500</property>
    <property name="can_focus">False</property>
    <property name="default_width">440</property>
    <property name="default_height">250</property>
    <child>
      <object class="GtkBox" id="box1">
        <property name="visible">True</property>
        <property name="can_focus">False</property>
        <property name="orientation">vertical</property>
        <child>
          <object class="GtkDrawingArea" id="play_here">
            <property name="visible">True</property>
            <property name="can_focus">False</property>
            <signal name="realize" handler="on_play_here_realize" swapped="no"/>
          </object>
          <packing>
            <property name="expand">True</property>
            <property name="fill">True</property>
            <property name="position">0</property>
          </packing>
        </child>
        <child>
          <object class="GtkSeparator" id="separator1">
            <property name="visible">True</property>
            <property name="can_focus">False</property>
          </object>
          <packing>
            <property name="expand">False</property>
            <property name="fill">True</property>
            <property name="position">1</property>
          </packing>
        </child>
        <child>
          <object class="GtkBox" id="box3">
            <property name="visible">True</property>
            <property name="can_focus">False</property>
            <child>
              <object class="GtkButtonBox" id="buttonbox1">
                <property name="visible">True</property>
                <property name="can_focus">False</property>
                <property name="layout_style">start</property>
                <child>
                  <object class="GtkButton" id="backward">
                    <property name="visible">True</property>
                    <property name="can_focus">True</property>
                    <property name="receives_default">True</property>
                    <property name="image">image1</property>
                    <property name="always_show_image">True</property>
                    <signal name="clicked" handler="on_backward_clicked" swapped="no"/>
                  </object>
                  <packing>
                    <property name="expand">True</property>
                    <property name="fill">True</property>
                    <property name="position">0</property>
                  </packing>
                </child>
                <child>
                  <object class="GtkButton" id="forward">
                    <property name="visible">True</property>
                    <property name="can_focus">True</property>
                    <property name="receives_default">True</property>
                    <property name="image">image2</property>
                    <property name="always_show_image">True</property>
                    <signal name="clicked" handler="on_forward_clicked" swapped="no"/>
                  </object>
                  <packing>
                    <property name="expand">True</property>
                    <property name="fill">True</property>
                    <property name="position">1</property>
                  </packing>
                </child>
                <child>
                  <object class="GtkToggleButton" id="playpause_togglebutton">
                    <property name="visible">True</property>
                    <property name="can_focus">True</property>
                    <property name="receives_default">True</property>
                    <property name="image">image3</property>
                    <property name="always_show_image">True</property>
                    <signal name="toggled" handler="on_playpause_togglebutton_toggled" swapped="no"/>
                  </object>
                  <packing>
                    <property name="expand">True</property>
                    <property name="fill">True</property>
                    <property name="position">2</property>
                  </packing>
                </child>
              </object>
              <packing>
                <property name="expand">False</property>
                <property name="fill">False</property>
                <property name="position">0</property>
              </packing>
            </child>
            <child>
              <object class="GtkScale" id="progress">
                <property name="width_request">300</property>
                <property name="visible">True</property>
                <property name="can_focus">True</property>
                <property name="halign">center</property>
                <property name="margin_left">5</property>
                <property name="margin_right">5</property>
                <property name="adjustment">adjustment</property>
                <property name="fill_level">100</property>
                <property name="round_digits">1</property>
                <property name="draw_value">False</property>
                <signal name="change-value" handler="on_progress_change_value" swapped="no"/>
              </object>
              <packing>
                <property name="expand">False</property>
                <property name="fill">False</property>
                <property name="position">1</property>
              </packing>
            </child>
          </object>
          <packing>
            <property name="expand">False</property>
            <property name="fill">True</property>
            <property name="position">2</property>
          </packing>
        </child>
        <child>
          <object class="GtkButtonBox" id="buttonbox2">
            <property name="visible">True</property>
            <property name="can_focus">False</property>
            <property name="homogeneous">True</property>
            <property name="layout_style">expand</property>
            <child>
              <object class="GtkButton" id="vbutton">
                <property name="label" translatable="yes">Video</property>
                <property name="visible">True</property>
                <property name="can_focus">True</property>
                <property name="receives_default">True</property>
                <signal name="clicked" handler="on_vbutton_clicked" swapped="no"/>
              </object>
              <packing>
                <property name="expand">True</property>
                <property name="fill">True</property>
                <property name="position">0</property>
              </packing>
            </child>
            <child>
              <object class="GtkButton" id="ibutton">
                <property name="label" translatable="yes">Image</property>
                <property name="visible">True</property>
                <property name="can_focus">True</property>
                <property name="receives_default">True</property>
                <signal name="clicked" handler="on_ibutton_clicked" swapped="no"/>
              </object>
              <packing>
                <property name="expand">True</property>
                <property name="fill">True</property>
                <property name="position">1</property>
              </packing>
            </child>
            <child>
              <object class="GtkToggleButton" id="mute">
                <property name="label" translatable="yes">Mute</property>
                <property name="visible">True</property>
                <property name="can_focus">True</property>
                <property name="receives_default">True</property>
                <signal name="toggled" handler="on_mute_toggled" swapped="no"/>
              </object>
              <packing>
                <property name="expand">False</property>
                <property name="fill">True</property>
                <property name="position">2</property>
              </packing>
            </child>
            <child>
              <object class="GtkToggleButton" id="rotate">
                <property name="label" translatable="yes">Rotate</property>
                <property name="visible">True</property>
                <property name="can_focus">True</property>
                <property name="receives_default">True</property>
                <signal name="toggled" handler="on_rotate_toggled" swapped="no"/>
              </object>
              <packing>
                <property name="expand">True</property>
                <property name="fill">True</property>
                <property name="position">3</property>
              </packing>
            </child>
          </object>
          <packing>
            <property name="expand">False</property>
            <property name="fill">True</property>
            <property name="position">4</property>
          </packing>
        </child>
      </object>
    </child>
    <child type="titlebar">
      <object class="GtkHeaderBar">
        <property name="visible">True</property>
        <property name="can_focus">False</property>
        <property name="title">VLC based media player</property>
        <property name="show_close_button">True</property>
        <child>
          <placeholder/>
        </child>
      </object>
    </child>
  </object>
</interface>

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