fix stdin/stdout issues with ffmpeg on mp4 (#102)

examples/ffmpeg/Dockerfile

@@ -9,3 +9,4 @@ RUN apk update && \
     apk add --no-cache ffmpeg=="${FFMPEG_VERSION}"
 
 COPY scyllaridae.yml /app/scyllaridae.yml
+COPY cmd.sh /app/cmd.sh

examples/ffmpeg/cmd.sh

@@ -0,0 +1,61 @@
+#!/usr/bin/env bash
+
+set -eou pipefail
+
+SOURCE_EXT="$1"
+DESTINATION_EXT="$2"
+ARGS=()
+if [ "$#" -eq 3 ]; then
+  IFS=' ' read -r -a ARGS <<< "$3"
+fi
+
+TMP_DIR=$(mktemp -d)
+INPUT_FILE="$TMP_DIR/input.$SOURCE_EXT"
+OUTPUT_FILE="$TMP_DIR/output.$DESTINATION_EXT"
+
+cleanup() {
+  rm -rf "$TMP_DIR"
+}
+
+trap cleanup EXIT
+cat > "$INPUT_FILE"
+
+if [ "$DESTINATION_EXT" = "mp4" ]; then
+  cmd=(
+    ffmpeg -loglevel error
+    -f "$SOURCE_EXT"
+    -i "$INPUT_FILE"
+    "${ARGS[@]}"
+    -vcodec libx264
+    -preset medium
+    -acodec aac
+    -strict -2
+    -ab 128k
+    -ac 2
+    -async 1
+    -movflags faststart
+    -y
+    -f "$DESTINATION_EXT"
+    "$OUTPUT_FILE"
+  )
+  echo "${cmd[@]}" >&2
+  "${cmd[@]}" > /dev/null
+else
+  cmd=(
+    ffmpeg -loglevel error
+    -f "$SOURCE_EXT"
+    -i "$INPUT_FILE"
+    "${ARGS[@]}"
+    -y
+    -f "$DESTINATION_EXT"
+    "$OUTPUT_FILE"
+  )
+  echo "${cmd[@]}" >&2
+  "${cmd[@]}" > /dev/null
+fi
+
+if [ ! -f "$OUTPUT_FILE" ] || [ ! -s "$OUTPUT_FILE" ]; then
+  exit 1
+fi
+
+cat "$OUTPUT_FILE"

examples/ffmpeg/scyllaridae.yml

@@ -31,36 +31,8 @@ cmdByMimeType:
       - "-vcodec"
       - "png"
       - "-"
-  "video/mp4":
-    cmd: ffmpeg
-    args:
-      - "-f"
-      - "%source-mime-ext"
-      - "-i"
-      - "-"
-      - "%args"
-      - "-vcodec"
-      - "libx264"
-      - "-preset"
-      - "medium"
-      - "-acodec"
-      - "aac"
-      - "-strict"
-      - "-2"
-      - "-ab"
-      - "128k"
-      - "-ac"
-      - "2"
-      - "-async"
-      - "1"
-      - "-movflags"
-      - "faststart"
-      - "-y"
-      - "-f"
-      - "%destination-mime-ext"
-      - "-"
   default:
-    cmd: ffmpeg
+    cmd: /app/cmd.sh "%source-mime-ext" "%destination-mime-ext"  "%args"
     args:
       - "-f"
       - "%source-mime-ext"