chromaprint-fixed

@chromaprint ?= {} # Creating images comes down to choosing a 'shade of grey' from here. GRAYCODE = [ 0, 1, 3, 2 ] @chromaprint.GRAYCODE = GRAYCODE # Images # ====== # # Chromaprint does its work on "images" - 2 dimensional arrays which are # calculated from an input stream. integral = (image) -> result = [] image.forEach (row, i) -> result[i] ?= [] row.forEach (n, j) -> result[i][j] = n + (result[i ]?[j-1] ? 0) + (result[i-1]?[j ] ? 0) - (result[i-1]?[j-1] ? 0) result area = (image, x1, y1, x2, y2) -> x1 ?= 0 y1 ?= 0 x2 ?= image.length y2 ?= image[x2]?.length result = image[x2]?[y2] return 0 if x2 < x1 or y2 < y1 if x1 > 0 result -= image[x1-1][y2] result += image[x1-1][y1-1] if y1 > 0 result -= image[x2][y1-1] if y1 > 0 result measure = (image) -> h: image.length w: image[0].length ? 0 @chromaprint.Image = { integral, area, measure } # Filters # ======= # # A filter in chromaprint modifies a portion of an image. There are 5 # different filters available. The `filter` function takes as arguments: # 1. the type of filter (0-4) # 2. the y offset from where to apply the comparison # 3. the x offset from where to apply the comparison # 4. the width upon which to run the comparison # 5. the height upon which to run the comparison # 6. the actual comparison function (currently always subtraction, but log # subtraction is also available. filter = (type, y, w, h, cmp) -> cmp ?= filter.compare.subtractLog f = (img, x) -> filter[type](img, x, y, w, h, cmp) f.w = w f.h = h f.y = y f filter[0] = (img, x, y, w, h, cmp) -> # oooooooooooo a = area(img, x, y, x + w - 1, y + h - 1) # oooooooooooo b = 0 # oooooooooooo cmp(a, b) # oooooooooooo # oooooooooooo # oooooooooooo filter[1] = (img, x, y, w, h, cmp) -> # ............ h2 = h / 2 # ............ a = area(img, x, y + h2, x + w - 1, y + h - 1) # ............ b = area(img, x, y , x + w - 1, y + h2 - 1) # oooooooooooo cmp(a, b) # oooooooooooo # oooooooooooo filter[2] = (img, x, y, w, h, cmp) -> # ......oooooo w2 = w / 2 # ......oooooo a = area(img, x + w2, y, x + w - 1, y + h - 1) # ......oooooo b = area(img, x , y, x + w2 - 1, y + y - 1) # ......oooooo cmp(a, b) # ......oooooo # ......oooooo filter[3] = (img, x, y, w, h, cmp) -> # ......oooooo [w2, h2] = [w / 2, h / 2] # ......oooooo a = area(img, x , y + h2, x + w2 - 1, y + h - 1) + # ......oooooo area(img, x + w2, y , x + w - 1, y + h2 - 1) # oooooo...... b = area(img, x , y , x + w2 - 1, y + h2 - 1) + # oooooo...... area(img, x + w2, y + h2, x + w - 1, y + h - 1) # oooooo...... cmp(a, b) filter[4] = (img, x, y, w, h, cmp) -> # ............ h3 = h / 3 # ............ a = area(img, x, y + h3, x + w - 1, y + 2 * h3 - 1) # oooooooooooo b = area(img, x, y , x + w - 1, y + h3 - 1) + # oooooooooooo area(img, x, y + 2 * h3, x + w - 1, y + h - 1) # ............ cmp(a, b) # ............ filter[5] = (img, x, y, w, h, cmp) -> # ....oooo.... w3 = w / 3 # ....oooo.... a = area(img, x + w3, y, x + 2 * w3 - 1, y + h - 1) # ....oooo.... b = area(img, x , y, x + w3 - 1, y + h - 1) + # ....oooo.... area(img, x + 2 * w3, y, x + w - 1, y + h -1) # ....oooo.... cmp(a, b) # ....oooo.... filter.compare = subtract: (a, b) -> a - b subtractLog: (a, b) -> Math.log(1 + a) - Math.log(1 + b) @chromaprint.filter = filter # Quantizer # ========= # # Makes a very simple function to return 0, 1, 2, or 3 depending on where the # value falls within the three values given. quantizer = (t0, t1, t2) -> (value) -> if value < t1 return 0 if value < t0 return 1 return 2 if value < t2 3 @chromaprint.quantizer = quantizer # Classifiers # =========== # # classifier is a higher order function that makes a filter and a quantizer # work together on an image. classifier = (coefficients) -> f = filter(coefficients.f...) q = quantizer(coefficients.q...) fn = (image, offset) -> q(f(image, offset)) fn.filterWidth = f.w fn @chromaprint.classifier = classifier # Calculator # ========== # # The calculator actually calculates the fingerprint of an image, by creating # the right classifier, and passing the image into the resulting function in # chunks. calculator = (coefficients...) -> classifiers = coefficients.map (cc) -> classifier(cc) max = classifiers.reduce ((w, c) -> Math.max(w, c.filterWidth)), 0 subfingerprint = (image, offset) -> classify = (b, classifier) -> (b << 2) | GRAYCODE[classifier(image, offset)] classifiers.reduce classify, 0 (image) -> length = measure(image).h - max + 1 img = integral(image) subfingerprint(img, offset) for offset in [0...length] @chromaprint.calculator = calculator