Class: Rubycam::GTK::Video4Linux

Inherits:
Object
  • Object
show all
Defined in:
lib/rubycam/gtk/video4linux.rb

Constant Summary collapse

FRAME_INTERVAL_MS = 
16
SLIDER_KEYS = 
%i[pan_absolute tilt_absolute zoom_absolute
brightness contrast saturation sharpness].freeze
WINDOW_SIZE = 
[1120, 640].freeze
STREAM_ERRORS_BEFORE_DROP =

After this many consecutive frame-pump errors the camera is treated as gone (a single hiccup while a stream rebuilds must not drop the handle).

60
WATCHDOG_SECONDS =

Longer than the camera's first-frame latency, so warmup after a stream (re)start is never mistaken for a dead stream.

5

Instance Method Summary collapse

Constructor Details

#initialize(device_path) ⇒ Video4Linux

Returns a new instance of Video4Linux.



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# File 'lib/rubycam/gtk/video4linux.rb', line 18

def initialize(device_path)
  @device_path = device_path
end

Instance Method Details

#app ⇒ Object 



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# File 'lib/rubycam/gtk/video4linux.rb', line 77

def app = @app ||= Gtk::Application.new('org.rubycam.v4l2', :default_flags)

#build ⇒ Object 



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# File 'lib/rubycam/gtk/video4linux.rb', line 22

def build
  app.tap do
    app.signal_connect('activate') do
      app.add_window(window)

      window.tap do |win|
        win.title = window_title
        win.set_default_size(*WINDOW_SIZE)
        win.child = layout

        win.signal_connect('close-request') do
          GLib::Source.remove(@pump) if @pump
          close_device
          false
        end
      end

      layout.tap do |l|
        l.append(picture)
        l.append(sidebar)

        sidebar.tap do |side|
          sliders.each_value { |s| side.append(s) }
          side.append(reset_button)
          @sliders_in_sidebar = !sliders.empty?

          reset_button.tap do |btn|
            btn.signal_connect('clicked') { reset_controls }
          end
        end
      end

      start_frame_pump
      start_reconnect_watch
      window.present
    end
  end
end

#close_device ⇒ Object 



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# File 'lib/rubycam/gtk/video4linux.rb', line 154

def close_device
  @device&.close
rescue SystemCallError
  nil
ensure
  @device = nil
end

#device ⇒ Object

Accepts a device path, a /dev name, or a card/bus substring (e.g. 'Integrated Camera').



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# File 'lib/rubycam/gtk/video4linux.rb', line 63

def device
  @device ||= (Rubycam::Device.find(@device_path) or
               raise Errno::ENOENT, @device_path).tap do |cam|
    cam.set_format(width: 1280, height: 720, pixel_format: 'MJPG')
    cam.set_fps(30)
  end
end

#layout ⇒ Object 



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# File 'lib/rubycam/gtk/video4linux.rb', line 79

def layout = @layout ||= Gtk::Box.new(:horizontal, 12)

#monotonic_now ⇒ Object 



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# File 'lib/rubycam/gtk/video4linux.rb', line 225

def monotonic_now = Process.clock_gettime(Process::CLOCK_MONOTONIC)

#picture ⇒ Object 



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# File 'lib/rubycam/gtk/video4linux.rb', line 81

def picture
  @picture ||= Gtk::Picture.new.tap do |pic|
    pic.hexpand = true
    pic.vexpand = true
    pic.margin_start = 12
    pic.margin_top = 12
    pic.margin_bottom = 12
  end
end

#pump_one_frame ⇒ Object 



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# File 'lib/rubycam/gtk/video4linux.rb', line 204

def pump_one_frame
  device.poll_frame.then do |frame|
    if frame
      @last_frame_at = monotonic_now
      @stream_errors = 0
      show_frame(frame)
    elsif monotonic_now - (@last_frame_at || 0) > WATCHDOG_SECONDS
      # Video should be flowing but is not: rebuild the stream until frames
      # return.
      @last_frame_at = monotonic_now
      warn 'video stalled: rebuilding stream'
      device.restart_streaming
    end
  end
rescue SystemCallError, RuntimeError
  # Sustained errors mean the camera is gone: drop the handle so the
  # reconnect watch re-finds it. A one-off hiccup is ignored.
  @stream_errors = (@stream_errors || 0) + 1
  close_device if @stream_errors >= STREAM_ERRORS_BEFORE_DROP
end

#reconnect_camera ⇒ Object 



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# File 'lib/rubycam/gtk/video4linux.rb', line 143

def reconnect_camera
  device.then do
    @stream_errors = 0
    @last_frame_at = monotonic_now
    restore_sliders
    window.title = window_title
  end
rescue SystemCallError
  nil
end

#reset_button ⇒ Object 



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# File 'lib/rubycam/gtk/video4linux.rb', line 108

def reset_button
  @reset_button ||= Gtk::Button.new(label: 'Reset to defaults').tap do |btn|
    btn.margin_top = 12
  end
end

#reset_controls ⇒ Object 



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# File 'lib/rubycam/gtk/video4linux.rb', line 172

def reset_controls
  sliders.each_key do |key|
    device.controls[key].then do |ctrl|
      set_control_safely(key, ctrl.default)
      slider_scale(key).value = ctrl.default
    end
  end
end

#restore_sliders ⇒ Object

When the app started without a camera the sidebar has no sliders yet; build and attach them on first successful (re)connect.



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# File 'lib/rubycam/gtk/video4linux.rb', line 164

def restore_sliders
  unless @sliders_in_sidebar || sliders.empty?
    sliders.each_value { |s| sidebar.append(s) }
    sidebar.reorder_child_after(reset_button, sidebar.last_child)
    @sliders_in_sidebar = true
  end
end

#set_control_safely(key, value) ⇒ Object

Control writes can fail transiently (EIO/EBUSY); an exception here must never kill the main loop.



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# File 'lib/rubycam/gtk/video4linux.rb', line 185

def set_control_safely(key, value)
  device.controls[key].value = value
rescue SystemCallError
  nil
end

#show_frame(jpeg) ⇒ Object 



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# File 'lib/rubycam/gtk/video4linux.rb', line 227

def show_frame(jpeg)
  GdkPixbuf::PixbufLoader.new.tap do |loader|
    loader.write(jpeg)
    loader.close
    picture.pixbuf = loader.pixbuf
  end
rescue GLib::Error
  nil # drop corrupt frames rather than crashing the pump
end

#sidebar ⇒ Object 



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# File 'lib/rubycam/gtk/video4linux.rb', line 91

def sidebar
  @sidebar ||= Gtk::Box.new(:vertical, 6).tap do |box|
    box.margin_top = 12
    box.margin_bottom = 12
    box.margin_end = 12
    box.width_request = 260
  end
end

#slider_for(ctrl) ⇒ Object 



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# File 'lib/rubycam/gtk/video4linux.rb', line 114

def slider_for(ctrl)
  Gtk::Box.new(:vertical, 2).tap do |box|
    box.append(Gtk::Label.new(ctrl.key.to_s).tap { |l| l.halign = :start })
    box.append(
      Gtk::Scale.new(:horizontal,
                     Gtk::Adjustment.new(ctrl.value, ctrl.min, ctrl.max,
                                         ctrl.step, ctrl.step * 10, 0)).tap do |scale|
        scale.draw_value = false
        scale.signal_connect('value-changed') do
          set_control_safely(ctrl.key, scale.value.round)
        end
      end
    )
  end
end

#slider_scale(key) ⇒ Object 



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# File 'lib/rubycam/gtk/video4linux.rb', line 181

def slider_scale(key) = sliders[key].last_child

#sliders ⇒ Object 



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# File 'lib/rubycam/gtk/video4linux.rb', line 100

def sliders
  @sliders ||= SLIDER_KEYS.filter_map do |key|
    device.controls[key]&.then { |ctrl| [key, slider_for(ctrl)] }
  end.to_h
rescue SystemCallError
  {}
end

#start_frame_pump ⇒ Object 



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# File 'lib/rubycam/gtk/video4linux.rb', line 191

def start_frame_pump
  @last_frame_at = monotonic_now
  @stream_errors = 0
  @pump = GLib::Timeout.add(FRAME_INTERVAL_MS) do
    pump_one_frame if @device
    GLib::Source::CONTINUE
  end
end

#start_reconnect_watch ⇒ Object

Drop the dead handle and try to find the camera again on every tick until it returns (unplugged or re-enumerated).



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# File 'lib/rubycam/gtk/video4linux.rb', line 136

def start_reconnect_watch
  GLib::Timeout.add_seconds(2) do
    reconnect_camera unless @device
    GLib::Source::CONTINUE
  end
end

#window ⇒ Object 



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# File 'lib/rubycam/gtk/video4linux.rb', line 78

def window = @window ||= Gtk::ApplicationWindow.new(app)

#window_title ⇒ Object 



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# File 'lib/rubycam/gtk/video4linux.rb', line 71

def window_title
  device.card
rescue SystemCallError
  'Rubycam V4L2 (no camera)'
end