most of program1 is done, shape of program2, actual app to be started

program1/rotation.sh

@@ -0,0 +1,46 @@
+get_rotation_filter() {
+    local f="$1"
+    local rotation
+    rotation=$(exiftool -Rotation -n "$f" | awk '{print $3}')
+    # echo $rotation $f >> "rotations.txt"
+    case "$rotation" in
+        # 90)  echo "transpose=1" ;;
+        # 270) echo "transpose=2" ;;
+        # 180) echo "hflip,vflip" ;;
+        # *)   echo "" ;;
+        *) echo "transpose=1" ;;
+    esac
+}
+export -f get_rotation_filter
+
+reencode_with_rotation() {
+    local src="$1"
+    local dst="$2"
+    local filter
+    filter="$(get_rotation_filter "$src")"
+
+    if [ -n "$filter" ]; then
+        echo "  Correction d’orientation (rotation=${filter})"
+        if ffmpeg -encoders 2>/dev/null | grep -q 'h264_videotoolbox'; then
+            ffmpeg -nostdin -i "$src" -vf "$filter" \
+                -c:v h264_videotoolbox -b:v 5M -c:a aac -map_metadata -1 -y "$dst"
+        else
+            ffmpeg -nostdin -i "$src" -vf "$filter" \
+                -c:v libx264 -preset fast -crf 18 -c:a aac -map_metadata -1 -y "$dst"
+        fi
+    else
+        # Pas de rotation → simple copie (ou réencodage minimal)
+        if ffmpeg -y -i "$src" -c copy -map 0 -movflags +faststart "$dst" < /dev/null 2>/dev/null; then
+            :
+        else
+            if ffmpeg -encoders 2>/dev/null | grep -q 'h264_videotoolbox'; then
+                ffmpeg -nostdin -i "$src" \
+                    -c:v h264_videotoolbox -b:v 5M -c:a aac -map_metadata -1 -y "$dst"
+            else
+                ffmpeg -nostdin -i "$src" \
+                    -c:v libx264 -preset fast -crf 18 -c:a aac -map_metadata -1 -y "$dst"
+            fi
+        fi
+    fi
+}
+export -f reencode_with_rotation