speedup.clj

#!/usr/bin/env boot

(require '[clojure.java.io :as io])

(defn inputs
  [input-dir]
  (->> (io/file input-dir)
       file-seq
       (filter #(.isFile %))))

(defn dir-uri
  [path]
  (-> (io/file path)
      .toURI
      (str "/")
      java.net.URI.))

(defn output-for
  [input-dir output-dir path]
  (let [rel (.relativize (.toURI (io/file input-dir)) (.toURI path))]
    (.getPath (.resolve (dir-uri output-dir) rel))))

(def ^:dynamic *bin* "ffmpeg")

(defn bin [] *bin*)

(defn ffmpeg! [& args]
  (apply dosh (map str (cons *bin* args))))

(defn -main [input-dir output-dir]
  (let [inputs (inputs input-dir)
        outputs (map (partial output-for input-dir output-dir) inputs)]
    (dosh "mkdir" "-p" output-dir)
    (doseq [[in out] (map vector inputs outputs)]
      (ffmpeg! "-i" in "-filter_complex" "setpts=PTS/1.7;atempo=1.7" "-strict" "-2" out))))