A Ben Fry video capture sketch in ruby-processing

A more funky video capture example in ruby-processing, in my hands this sketch seems to require the --nojruby flag.

#
# ASCII Video
# by Ben Fry, translated to ruby-processing by Martin Prout.
#
#
# Text chars have been used to represent images since the earliest computers.
# This sketch is a simple homage that re-interprets live video as ASCII text.
# See the key_pressed function for more options, like changing the font size.
#
load_library :video
include_package 'processing.video'

attr_reader :bright, :char, :cheat_screen, :font, :font_size, :letters, :video

# All ASCII characters, sorted according to their visual density
LETTER_STRING = %q{ .`-_':,;^=+/\"|)\\<>)iv%xclrs{*}I?!][1taeo7zjLunT#JCwfy325Fp6mqSghVd4EgXPGZbYkOA&8U$@KHDBWNMR0Q}
LETTER_ORDER = LETTER_STRING.scan(/./)
def setup
  size(640, 480)
  init_video
  @font_size = 1.5
  @font = load_font(data_path('UniversLTStd-Light-48.vlw'))
  # for the 256 levels of brightness, distribute the letters across
  # the an array of 256 elements to use for the lookup
  @letters = (0...256).map do |i|
    LETTER_ORDER[map1d(i, (0...256), (0...LETTER_ORDER.length))]
  end
  # current brightness for each point
  @bright = Array.new(video.width * video.height, 128)
end

def init_video
  # This the default video input, see the test_capture
  # example if it creates an error
  @video = Capture.new(self, 160, 120)
  # Start capturing the images from the camera
  video.start
  @cheat_screen = false
end

def capture_event(c)
  c.read
  background 0
end

def draw
  return unless (video.available == true)
  capture_event(video)
  push_matrix
  hgap = width / video.width
  vgap = height / video.height
  scale([hgap, vgap].max * font_size)
  text_font(font, font_size)
  index = 0
  video.load_pixels
  (0...video.height).each do
    # Move down for next line
    translate(0,  1.0 / font_size)
    push_matrix
    (0...video.width).each do
      pixel_color = video.pixels[index]
      # Faster method of calculating r, g, b than red(), green(), blue()
      r = pixel_color >> 16 & 0xff
      g = pixel_color >> 8 & 0xff
      b = pixel_color & 0xff
      # Another option would be to properly calculate brightness as luminance:
      # luminance = 0.3*red + 0.59*green + 0.11*blue
      # Or you could instead red + green + blue, and make the the values[] array
      # 256*3 elements long instead of just 256.
      pixel_bright = [r, g, b].max
      # The 0.1 value is used to damp the changes so that letters flicker less
      diff = pixel_bright - bright[index]
      bright[index] += diff * 0.1
      fill(pixel_color)
      text(letters[bright[index]], 0, 0)
      # Move to the next pixel
      index += 1
      # Move over for next character
      translate(1.0 / font_size, 0)
    end
    pop_matrix
  end
  pop_matrix
  # image(video, 0, height - video.height)
  # set() is faster than image() when drawing untransformed images
  set(0, height - video.height, video) if cheat_screen
end

MESSAGE = <<-EOS
Controls are:
  g to save_frame, f & F to set font size
  c to toggle cheat screen display
EOS

#
# Handle key presses:
# 'c' toggles the cheat screen that shows the original image in the corner
# 'g' grabs an image and saves the frame to a tiff image
# 'f' and 'F' increase and decrease the font size
#
def key_pressed
  case key
  when 'g' then save_frame
  when 'c' then @cheat_screen = !cheat_screen
  when 'f' then @font_size *= 1.1
  when 'F' then @font_size *= 0.9
  else
    warn MESSAGE
  end
end

Video capture with ruby-processing

Simple sketch to get you started with video capture on ruby-processing, makes sense to set sketch to dimensions you think that your camera can work with (use cameras instead of select for an unfiltered list, but it can be very long list as many low resolution cameras get listed, each with lots of fps settings).

load_library :video

include_package 'processing.video'

attr_reader :cam

def setup
  size(960, 544)
  cameras = Capture.list
  fail 'There are no cameras available for capture.' if (cameras.length == 0)
  p 'Matching cameras available:'
  size_pattern = Regexp.new(format('%dx%d', width, height))
  select = cameras.grep size_pattern # filter available cameras
  select.map { |cam| p cam }
  fail 'There are no matching cameras.' if (select.length == 0)
  start_capture(select[0])
end

def start_capture(cam_string)
  # The camera can be initialized directly using an
  # element from the array returned by list:
  @cam = Capture.new(self, cam_string)
  p format('Using camera %s', cam_string)
  cam.start
end

def draw
  return unless (cam.available == true)
  cam.read
  image(cam, 0, 0)
  # The following does the same, and is faster when just drawing the image
  # without any additional resizing, transformations, or tint.
  # set(0, 0, cam)
end