Add Gosu::Video

[cyberarm]

Currently a stub.

An ffmpeg/libvlc backed implementation that'll emulate the Gosu::Image and Gosu::Song public interfaces.

Gosu::Window::tick() will likely need to call Gosu::Video::update() on all videos; A static vector in Gosu::Video can host and maintain the list.

The implementation is wrapped in an #ifdef to allow Gosu::Video to be an optional feature.

[cyberarm]

@jlnr What do you think of this approach?

TODO:

• Prevent concurrent read/write of Image data
• Check for errors when creating libvlc_ objects
• See why libvlc doesn't seem to like :borderless and if it can be fixed
• Add libvlc to /dependencies
• Link against libvlc on Windows and Mac

Video support is behind the -DGOSU_ENABLE_VIDEO flag

Working example:

require_relative "ffi-gosu/lib/gosu"
require_relative "ffi-gosu/lib/gosu/video"


class Window < Gosu::Window
  def initialize
    super(800, 600, false, 16.6667, true, false)

    @video = Gosu::Video.new("/home/cyberarm/Downloads/big-buck-bunny_trailer.webm")

    pp @video.width, @video.height, @video.length, @video.position

    calculate_scale
  end

  def draw
    Gosu.draw_rect(0, 0, width, height, Gosu::Color::WHITE)
    @video.draw(0, 0, 0, @scale, @scale)
  end

  def update
    calculate_scale
  end

  def button_down(id)
    @video.play if id == Gosu::KB_SPACE
    @video.stop if id == Gosu::KB_LEFT_CONTROL
  end

  def calculate_scale
    @scale = [
      [
        width / @video.width.to_f,
        height / @video.height.to_f
      ].min,
      [
        width / @video.width.to_f,
        height / @video.height.to_f
      ].max
    ].min
  end
end

Window.new.show

[jlnr]

Wow, thanks for this. I didn't review all of it, but I left a couple of code comments.

My biggest worry with video support is shippability. ImageMagick seemed like a similar swiss army knife as VLC, but then packaging a Ruby/Gosu game with ImageMagick for Windows turned out to be a huge timesink. (I vaguely remember wrestling with ImageMagick "all in one" builds...)
Is VLC a single DLL that we can ship?

There was also an issue with example code for libtheora, I'm not sure how it compares to libvlc in terms of self-containedness: #349

(As long as it is hidden behind a compiler flag, this is not really a blocker. If video support is only a couple of extra files, why not!)

[cyberarm]

My biggest worry with video support is shippability. ImageMagick seemed like a similar swiss army knife as VLC, but then packaging a Ruby/Gosu game with ImageMagick for Windows turned out to be a huge timesink. (I vaguely remember wrestling with ImageMagick "all in one" builds...)
Is VLC a single DLL that we can ship?

For libvlc we'd need to include libvlc.dll, 'libvlccore.dll, and any required vlc plugins and codecs to playback video; We should probably only include playback support for ogg, webm, and av1, i.e. royality-free codecs, since they can be a landmine for commercial projects.
libvlc needs the VLC_PLUGIN_PATH environment variable set to locate plugins. It should be easy enough for users to add additional plugins/codecs that they may need.

There was also an issue with example code for libtheora, I'm not sure how it compares to libvlc in terms of self-containedness: #349

The gists @Dahrkael linked to for libtheoraplayer are returning 404s and the waybackmachine doesn't have them.

[jlnr]

Okay, that sounds good 👍 I was worried that we might need to ship a whole zoo of Unix-ish libraries.