cut_resize_normalize.sh

#!/usr/bin/env bash

INPUT_FILE="${1}"
TIME_START="${2}"  # expected format HH:MM:SS
TIME_DURATION="${3}"  # expected format HH:MM:SS
OUTPUT_FILE="${4}"

BASE="$(basename "${INPUT_FILE}")"
SHM_AUDIO_FILE="/dev/shm/audio_${BASE}"
SHM_VIDEO_FILE="/dev/shm/video_${BASE}"
SHM_FILE="/dev/shm/${BASE}.mp4"
JSON="/dev/shm/${$}.json"


# Video: cutting, resizing, resampling
ffmpeg \
    -i "${INPUT_FILE}" \
    -y \
    -ss "${TIME_START}" \
    -t "${TIME_DURATION}" \
    -vcodec h264 \
    -vf "scale=1080:-1" \
    -an \
    "${SHM_VIDEO_FILE}"

# Audio: normalization data
ffmpeg \
    -i "${INPUT_FILE}" \
    -y \
    -ss "${TIME_START}" \
    -t "${TIME_DURATION}" \
    -vn \
    -b:a 256k \
    -ar 48000 \
    -pass 1 \
    -filter:a loudnorm=print_format=json \
    -f ac3 \
    /dev/null >> "${JSON}" 2>> "${JSON}"

input_i="$(grep 'input_i' "${JSON}" | awk -F':' '{print $2}' | grep -o '".*"' | sed 's,",,g')"
input_tp="$(grep 'input_tp' "${JSON}" | awk -F':' '{print $2}' | grep -o '".*"' | sed 's,",,g')"
input_lra="$(grep 'input_lra' "${JSON}" | awk -F':' '{print $2}' | grep -o '".*"' | sed 's,",,g')"
input_thresh="$(grep 'input_thresh' "${JSON}" | awk -F':' '{print $2}' | grep -o '".*"' | sed 's,",,g')"

ffmpeg \
    -i "${INPUT_FILE}" \
    -y \
    -ss "${TIME_START}" \
    -t "${TIME_DURATION}" \
    -vn \
    -b:a 256k \
    -ar 48000 \
    -pass 2 \
    -af "loudnorm=linear=true:measured_I=${input_i}:measured_LRA=${input_lra}:measured_tp=${input_tp}:measured_thresh=${input_thresh}" \
    -acodec ac3 \
    "${SHM_AUDIO_FILE}"

ffmpeg \
    -i "${SHM_AUDIO_FILE}" \
    -i "${SHM_VIDEO_FILE}" \
    -c copy \
    "${SHM_FILE}"

rsync -avh "${SHM_FILE}" "${OUTPUT_FILE}"


rm "${JSON}"
rm "${SHM_VIDEO_FILE}"
rm "${SHM_AUDIO_FILE}"
rm "${SHM_FILE}"