update mediatools to 9a61482, add cachebuster to dockerfile

docker/app/Dockerfile

@@ -1,5 +1,9 @@
 FROM elixir:1.10.3
 
+# cache bust git repos
+ADD https://api.github.com/repos/derpibooru/cli_intensities/git/refs/heads/master /tmp/cli_intensities_version.json
+ADD https://api.github.com/repos/derpibooru/mediatools/git/refs/heads/master /tmp/mediatools_version.json
+
 RUN apt-get update; \
     apt-get -qq -y install apt-transport-https; \
     echo "deb https://deb.nodesource.com/node_12.x stretch main" >> /etc/apt/sources.list; \
@@ -7,12 +11,12 @@ RUN apt-get update; \
     wget -qO - https://www.postgresql.org/media/keys/ACCC4CF8.asc | apt-key add -; \
     wget -qO - https://deb.nodesource.com/gpgkey/nodesource.gpg.key | apt-key add -; \
     apt-get update; \
-    apt-get -qq -y install inotify-tools postgresql-client build-essential git ffmpeg libavformat-dev libavcodec-dev nodejs libmagic-dev libpng-dev gifsicle optipng libjpeg-progs librsvg2-bin; \
+    apt-get -qq -y install inotify-tools postgresql-client build-essential git ffmpeg libavformat-dev libavcodec-dev libswscale-dev nodejs libmagic-dev libpng-dev gifsicle optipng libjpeg-progs librsvg2-bin; \
     cd /tmp; \
     git clone https://github.com/derpibooru/cli_intensities; \
     git clone https://github.com/derpibooru/mediatools; \
-    (cd cli_intensities; make install); \
-    (cd mediatools; make install); \
+    (cd cli_intensities && make install); \
+    (cd mediatools && make install); \
     mix local.hex --force; \
     mix local.rebar --force
 

lib/philomena/processors/gif.ex

@@ -35,37 +35,9 @@ defmodule Philomena.Processors.Gif do
   end
 
   defp preview(duration, file) do
-    h264_equiv = Briefly.create!(extname: ".mp4")
     preview = Briefly.create!(extname: ".png")
 
-    # Hack workaround for broken FFmpeg behavior which
-    # cannot correctly seek in GIF image files
-
-    {_output, 0} =
-      System.cmd("ffmpeg", [
-        "-loglevel",
-        "0",
-        "-y",
-        "-i",
-        file,
-        "-c:v",
-        "libx264",
-        h264_equiv
-      ])
-
-    {_output, 0} =
-      System.cmd("ffmpeg", [
-        "-loglevel",
-        "0",
-        "-y",
-        "-i",
-        h264_equiv,
-        "-ss",
-        to_string(duration / 2),
-        "-frames:v",
-        "1",
-        preview
-      ])
+    {_output, 0} = System.cmd("mediathumb", [file, to_string(duration / 2), preview])
 
     preview
   end

lib/philomena/processors/webm.ex

@@ -28,19 +28,7 @@ defmodule Philomena.Processors.Webm do
   defp preview(duration, file) do
     preview = Briefly.create!(extname: ".png")
 
-    {_output, 0} =
-      System.cmd("ffmpeg", [
-        "-loglevel",
-        "0",
-        "-y",
-        "-i",
-        file,
-        "-ss",
-        to_string(duration / 2),
-        "-frames:v",
-        "1",
-        preview
-      ])
+    {_output, 0} = System.cmd("mediathumb", [file, to_string(duration / 2), preview])
 
     preview
   end