#!/bin/bash

PARAM=$0
# Strip path and cmd_ prefix from command name
PARAM=${PARAM##*/cmd_}

short() {
  echo "Decode AVC (H.264) video and save as YUV 420P raw file"
}

help() {
cat << EOF
$(short)

$(info)

IN_FILE   Input stream must be AVC (H.264) video
OUT_FILE  Output stream as YUV 420P

NOTE: Above paths are read from the container volume /media.

EOF
}

details() {
cat << EOF
$(short)

This script provides a quick reference example using the following
ffmpeg command:

  ffmpeg \
    -hwaccel qsv \
    -qsv_device \${QSV_DEVICE:-/dev/dri/renderD128} \
    -c:v h264_qsv \
    -i /media/"\${IN_FILE}" \
    -vf hwdownload,format=nv12 -pix_fmt yuv420p \
    -y \
    /media/"\${OUT_FILE}"

EOF
}

arguments=()
for arg in $*; do
  [[ $arg =~ ^-- ]] && {
    command=${arg/--}
    case $command in
    short) short
        exit 0
	;;
    help) help
        exit 0
	;;
    details) details
        exit 0
        ;;
    *) echo "Unrecognized command."
	exit 1
	;;
    esac
  } || {
    arguments+=("$arg")
  }
done

info() {
  cat << EOF
usage: $PARAM INPUT-FILE OUTPUT-FILE
EOF
}

QSV_DEVICE=${QSV_DEVICE:-/dev/dri/renderD128}

[ "${arguments[0]}" == "" ] || [ "${arguments[1]}" == "" ] && {
  info
  exit 1
}

[ ! -e /media/"${arguments[0]}" ] && {
  cat << EOF
Error: '${arguments[0]}' not found.

Was the volume /media mounted when launching the container?

    docker ... --volume \$(pwd)/media:/media ...

or similar?

EOF

  exit 1
}

[ ! -e ${QSV_DEVICE} ] && {
cat << EOF

Error: '${QSV_DEVICE}' not found.

Did you pass /dev/dri to Docker?

    docker ... --device=/dev/dri ...

or similar?

EOF
  exit 2
}

IN_FILE="${arguments[0]}"
OUT_FILE="${arguments[1]}"

  ffmpeg \
    -hwaccel qsv \
    -qsv_device ${QSV_DEVICE:-/dev/dri/renderD128} \
    -c:v h264_qsv \
    -i /media/"${IN_FILE}" \
    -vf hwdownload,format=nv12 -pix_fmt yuv420p \
    -y \
    /media/"${OUT_FILE}"