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@scottdw

scottdw/jpeg.clj

Last active December 24, 2015 14:29
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Revisions

  1. scottdw revised this gist Oct 9, 2013. 1 changed file with 34 additions and 10 deletions.
    44 changes: 34 additions & 10 deletions jpeg.clj
    View file
    Original file line number Diff line number Diff line change
    @@ -1,10 +1,29 @@
    (ns scottdw.jpeg
    (:import [clojure.lang Keyword]
    [com.drew.imaging ImageMetadataReader]
    [com.drew.metadata Directory Metadata Tag]
    [java.net URI]
    [java.nio ByteBuffer]
    [java.nio.file Files Paths])
    (:require [clojure.java.io :as io]))

    (defn read-metadata [^String file-name]
    (-> file-name io/file ImageMetadataReader/readMetadata))

    (defn metadata-to-string [^Metadata metadata]
    (let [sb (StringBuilder.)]
    (doseq [^Directory d (.getDirectories metadata)]
    (.append sb (.getName d))
    (.append sb \newline)
    (doseq [^Tag t (.getTags d)]
    (doto sb
    (.append \tab)
    (.append (.getTagName t))
    (.append " : ")
    (.append (.getDescription t))
    (.append \newline))))
    (.toString sb)))

    (defn read-into-byte-buffer [^String file-name]
    (-> file-name io/file .toPath Files/readAllBytes ByteBuffer/wrap))

    @@ -74,18 +93,23 @@
    (if (= b (unchecked-byte 0xFF))
    (if (marker-map (unchecked-short (bit-or (bit-shift-left b 8)
    (.get bb))))
    (doto bb (.position p))
    (do (.position bb p) p)
    (recur (doto bb (.position (inc p)))))
    (recur bb)))))
    (recur bb)))
    -1))

    (defn read-marker [^ByteBuffer bb]
    (if (seek-next-marker bb)
    (let [p (.position bb)
    m (.getShort bb)
    {:keys [segment symbol] :as marker} (marker-map m)]
    (when segment
    (do (.position bb (+ p (+ (.getShort bb) 2)))))
    [symbol p])))
    (let [p (.position bb)
    m (.getShort bb)
    {:keys [segment symbol] :as marker} (marker-map m)]
    (when segment
    (do (.position bb (+ p (+ (.getShort bb) 2)))))
    (let [np (seek-next-marker bb)]
    [symbol p (- (if (neg? np) (.limit bb) np) p)])))

    (defn read-all-markers [^ByteBuffer bb]
    (take-while identity (repeatedly #(read-marker bb))))
    (let [dup (doto (.duplicate bb) (.position 0))]
    (loop [markers []]
    (if (neg? (seek-next-marker dup))
    markers
    (recur (conj markers (read-marker dup)))))))
  2. scottdw revised this gist Oct 3, 2013. 1 changed file with 1 addition and 1 deletion.
    2 changes: 1 addition & 1 deletion jpeg.clj
    View file
    Original file line number Diff line number Diff line change
    @@ -84,7 +84,7 @@
    m (.getShort bb)
    {:keys [segment symbol] :as marker} (marker-map m)]
    (when segment
    (do (.position bb (+ p (+ (.getShort bb) 2))) [symbol p]))
    (do (.position bb (+ p (+ (.getShort bb) 2)))))
    [symbol p])))

    (defn read-all-markers [^ByteBuffer bb]
  3. scottdw created this gist Oct 3, 2013.
    91 changes: 91 additions & 0 deletions jpeg.clj
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,91 @@
    (ns scottdw.jpeg
    (:import [clojure.lang Keyword]
    [java.net URI]
    [java.nio ByteBuffer]
    [java.nio.file Files Paths])
    (:require [clojure.java.io :as io]))

    (defn read-into-byte-buffer [^String file-name]
    (-> file-name io/file .toPath Files/readAllBytes ByteBuffer/wrap))

    (defrecord Marker [^short code-assignment ^Keyword symbol ^String description ^boolean segment])

    (defn make-markers [start-value end-value keyword-prefix description-format segment]
    (let [n (inc (- end-value start-value))]
    (map #(Marker. (unchecked-short (+ start-value %))
    (keyword (str keyword-prefix \_ %))
    (format description-format %)
    segment)
    (range n))))

    (def markers
    (reduce into
    [[
    ;; Start Of Frame markers, non-differential, Huffman coding
    (Marker. (unchecked-short 0xFFC0) :SOF_0 "Baseline DCT" true)
    (Marker. (unchecked-short 0xFFC1) :SOF_1 "Extended sequential DCT" true)
    (Marker. (unchecked-short 0xFFC2) :SOF_2 "Progressive DCT" true)
    (Marker. (unchecked-short 0xFFC3) :SOF_3 "Lossless (sequential)" true)
    ;; Start Of Frame markers, differential, Huffman coding
    (Marker. (unchecked-short 0xFFC5) :SOF_5 "Differential sequential DCT" true)
    (Marker. (unchecked-short 0xFFC6) :SOF_6 "Differential progressive DCT" true)
    (Marker. (unchecked-short 0xFFC7) :SOF_7 "Differential lossless (sequential)" true)
    ;; Start Of Frame markers, non-differential, arithmetic coding
    (Marker. (unchecked-short 0xFFC8) :JPG "Reserved for JPEG extensions" true)
    (Marker. (unchecked-short 0xFFC9) :SOF9 "Extended sequential DCT" true)
    (Marker. (unchecked-short 0xFFCA) :SOF10 "Progressive DCT" true)
    (Marker. (unchecked-short 0xFFCB) :SOF11 "Lossless (sequential)" true)
    ;; Start Of Frame markers, differential, arithmetic coding
    (Marker. (unchecked-short 0xFFCD) :SOF13 "Differential sequential DCT" true)
    (Marker. (unchecked-short 0xFFCE) :SOF14 "Differential progressive DCT" true)
    (Marker. (unchecked-short 0xFFCF) :SOF15 "Differential lossless (sequential)" true)
    ;; Huffman table specification
    (Marker. (unchecked-short 0xFFC4) :DHT "Define Huffman table(s)" true)
    ;; Arithmetic coding conditioning specification
    (Marker. (unchecked-short 0xFFCC) :DAC "Define arithmetic coding conditioning(s)" true)
    ;; Other markers
    (Marker. (unchecked-short 0xFFD8) :SOI "Start of image" false)
    (Marker. (unchecked-short 0xFFD9) :EOI "End of image" false)
    (Marker. (unchecked-short 0xFFDA) :SOS "Start of scan" true)
    (Marker. (unchecked-short 0xFFDB) :DQT "Define quantization table(s)" true)
    (Marker. (unchecked-short 0xFFDC) :DNL "Define number of lines" true)
    (Marker. (unchecked-short 0xFFDD) :DRI "Define restart interval" true)
    (Marker. (unchecked-short 0xFFDE) :DHP "Define hierarchical progression" true)
    (Marker. (unchecked-short 0xFFDF) :EXP "Expand reference component(s)" true)
    (Marker. (unchecked-short 0xFFFE) :COM "Comment" true)
    ;; Reserved markers
    (Marker. (unchecked-short 0xFF01) :TEM "For temporary private use in arithmetic coding" false)
    ]
    ;; Restart interval termination
    (make-markers 0xFFD0 0xFFD7 "RST" "Restart with modulo 8 count \"%1$s\"" false)
    ;; Reserved for application segments
    (make-markers 0xFFE0 0xFFEF "APP" "Application segment [%1$s]" true)
    ;; Reserved for JPEG extensions
    (make-markers 0xFFF0 0xFFFD "JPG" "JPEG extension [%1$s]" true)
    ;; Reserved
    (make-markers 0xFF02 0xFFBF "RES" "Reserved [%1$s]" true)]))

    (def marker-map (zipmap (map :code-assignment markers) markers))

    (defn seek-next-marker [^ByteBuffer bb]
    (if (> (.remaining bb) 1)
    (let [p (.position bb)
    b (.get bb)]
    (if (= b (unchecked-byte 0xFF))
    (if (marker-map (unchecked-short (bit-or (bit-shift-left b 8)
    (.get bb))))
    (doto bb (.position p))
    (recur (doto bb (.position (inc p)))))
    (recur bb)))))

    (defn read-marker [^ByteBuffer bb]
    (if (seek-next-marker bb)
    (let [p (.position bb)
    m (.getShort bb)
    {:keys [segment symbol] :as marker} (marker-map m)]
    (when segment
    (do (.position bb (+ p (+ (.getShort bb) 2))) [symbol p]))
    [symbol p])))

    (defn read-all-markers [^ByteBuffer bb]
    (take-while identity (repeatedly #(read-marker bb))))