gistfile1.clj

;;from http://stackoverflow.com/questions/502753/programmatically-convert-a-video-to-flv
(defn readerRecurse
  "calls .readPacket until there's nothing left to do2"
  [reader]
  (if (not (nil? (.readPacket reader))) ; here .readPacket actually does the processing as a side-effect.
    true                         ; it returns null when it has MORE ro process, and signals an error when done... 
    (recur reader)))

(defn generate-snapshots [filename destination n]
  (let [vid-stream-idx (atom -1)
        last-pts-write (atom Global/NO_PTS)
        container (doto (IContainer/make)
                    (.open filename IContainer$Type/READ nil))
        duration   (/ (.getDuration container) Global/DEFAULT_PTS_PER_SECOND)
        seconds-between-frames (long (/ duration n))       
        microseconds-between-frames (long (* Global/DEFAULT_PTS_PER_SECOND seconds-between-frames))
        reader (ToolFactory/makeReader container)]
    (doto reader
      (.setBufferedImageTypeToGenerate BufferedImage/TYPE_3BYTE_BGR)
      (.addListener
       (proxy [MediaListenerAdapter] []
         (onVideoPicture [event]
           (try
             (if (not= (.getStreamIndex event) @vid-stream-idx)
               (if (= -1 @vid-stream-idx)
                 (reset! vid-stream-idx (.getStreamIndex event))))
             (if (= @last-pts-write Global/NO_PTS)
               (reset! last-pts-write (- (.getTimeStamp event) microseconds-between-frames)))
             (when (>= (- (.getTimeStamp event) @last-pts-write) microseconds-between-frames)
               (ImageIO/write (.getImage event) "jpg"
                              (File/createTempFile "frame" ".jpg"
                                                   (File. destination)))
               (swap! last-pts-write #(+ % microseconds-between-frames)))
             (catch Exception e (str "caught exception: " (.getMessage e))))))))
    (readerRecurse reader)))