#!/bin/bash
# Transcodes a file to x264 with VA API acceleration.

# Set the $FILE variable to act on. Varies with file manager, but Dolphin's servicemenus and CLI both use $1
if ! [ -z $NAUTILUS_SCRIPT_SELECTED_FILE_PATHS ]; then
    echo "$NAUTILUS_SCRIPT_SELECTED_FILE_PATHS" > ~/.nautilus_script_selected_file_paths
    if (( $(grep -c . <<<"$(cat ~/.nautilus_script_selected_file_paths)") > 1 )); then notify-send -u critical "Script error" "Selecting more than 1 file is not supported."; exit 1; fi
    rm ~/.nautilus_script_selected_file_paths
    INPUT_FILE="$NAUTILUS_SCRIPT_SELECTED_FILE_PATHS"
elif ! [ -z "$1" ]; then 
    INPUT_FILE="$1"
else
    echo "No file selected."
    exit 1
fi

RATE_FACTOR=""
while [ -z "$RATE_FACTOR" ]; do
    RATE_FACTOR=$(kdialog --title "Transcode: x264 Rate factor" --inputbox "Rate factor (15-28, lower is higher fidelity, higher bitrate.")
    if ! (($RATE_FACTOR >= 15 && $RATE_FACTOR <= 28)); then
        RATE_FACTOR=""
    fi
done

# Break up the input file's parts so we know the:
# - absolute path (e.g. /home/user/Videos/MyVideo.mkv)
# - file name (with extension) (e.g. MyVideo.mkv)
# - file extension (e.g. mkv)
# - file name (without extension) (e.g. MyVideo)
# - composed output file absolute path (e.g. /home/user/Videos/MyVideo-clip.mp4)
INPUT_FILE=$(realpath "$INPUT_FILE")
FILE_PATH=$(dirname "$INPUT_FILE")
FILE_NAME=$(basename "$INPUT_FILE")
FILE_EXT="${FILE_NAME##*.}"
FILE_NAME="${FILE_NAME%.*}"
OUTFILE=$(echo "$FILE_PATH/$FILE_NAME.x264.$FILE_EXT")

# Actual transcoding happens here:
notify-send -t 2000 "Transcode starting" "$FILE_NAME"
ffmpeg -hide_banner -vaapi_device /dev/dri/renderD128 -i "$INPUT_FILE" -c:v h264_vaapi -qp $RATE_FACTOR -c:a copy "$OUTFILE"
notify-send -t 4000 "Transcode complete" "$FILE_NAME"